Epitope-specific impairment of production of antibody against merozoite surface glycoprotein 1 of Plasmodium falciparum in symptomatic patients with malaria

We analyzed the relationships between levels of antibody specific for merozoite surface glycoprotein-1 (MSP1) of Plasmodium falciparum and clinical manifestations in humans. We prepared recombinant MSP1 proteins representing block 3 (M3), block 6 (M6), blocks 1–6 (M1/6), and block 17. When we divided the slide-positive individuals in Guadalcanal into symptomatic and asymptomatic groups, the former group showed lower IgG levels against M6 and block 17, but not against M3, than did the asymptomatic group (P < 0.01). The possibility of nonspecific suppression was unlikely, given that the levels of antibody against poliomyelitis virus observed in the two groups were almost the same. Among the IgG subclasses tested, production of cytophilic IgG₃ seemed to be dominant. When we analyzed epitopes recognized by antibodies against block 17, a peptide (SSSNFLGIS) was preferentially recognized by sera from asymptomatic individuals. These results suggest that clinical symptoms occurring during falciparum malaria seem to be associated with the development of levels of antibody against particular epitopes on MSP1, which is under the control of an immunoregulatory mechanism. Received: 1 October 1999 / Accepted: 21 October 1999     

Fine structure of transforming-type granules in mucous cells in the early postnatal rat parotid gland when processed by rapid freezing followed by freeze-substitution fixation

The present study was designed to clarify the more precise ultrastructural feature of granules, especially mucous granules in the early postnatal rat parotid gland by using rapid freezing followed by freeze-substitution fixation. The parotid gland of Wistar rats (aged 0-10 days) was removed under anesthesia and immediately underwent cryofixation followed by substitution with osmium tetroxide. After fixation, the samples were embedded in Epon-Araldite, cut into ultrathin section, and then examined by transmission electron microscopy. Electron microscopy showed that the mucous granules of samples treated by freeze-substitution fixation had low electron density and were almost spherical in shape with a clear limiting membrane. By Day 5, granules that were a little more electron dense than mucous granules, granules with a more electron dense portion at their periphery, and heterogeneous granules with an internal highly electron dense portion were found. Moreover, cells containing both homogeneous granules with a high electron density similar to that of mature serous granules and heterogeneous granules were observed. These findings demonstrated that the morphology of the transforming-type mucous granules by chemical fixation in the previous study was an artifact and, as a result, strongly suggested that on the sequential morphological changes of transitional mucous/serous granules by rapid freezing method in the present study, the mucous cells in the early postnatal rat parotid gland undergo transformation to serous cells.     

Adhesion polypeptides are useful for the prevention of peritoneal dissemination of gastric cancer

We examined the effect of adhesion polypeptides on the adhesion and invasiveness of gastric cancer cell lines. We previously reported the establishment of an extensively peritoneal-seeding cell line, OCUM-2MD3, from a poorly seeding human scirrhous gastric carcinoma cell line, OCUM-2M. Both 21 and 31 integrin expression was markedly increased on OCUM-2MD3 cells compared with OCUM-2M cells, and the ability of OCUM-2MD3 cells to bind to the extracellular matrix (ECM) was also significantly higher than that of OCUM-2M cells. The adhesion polypeptides, YIGSR and RGD, and two RGD derivatives significantly inhibited the adhesion of OCUM-2MD3 cells to the submesothelial ECM, while not inhibiting the adhesiveness of OCUM-2M cells and two well differentiated human gastric cell lines, MKN-28 and MKN-74. The YIGSR and RGD peptides also significantly inhibited the invasiveness of OCUM-2MD3 cells. The survival of nude mice with peritoneal dissemination given YIGSR sequenc e intraperitoneally was obviously longer than that of untreated mice. The survival of mice treated with RGD was also improved, and this effect was increased using the RGD derivatives, poly(CEMA-RGDS) and CM-chitin RGDS. These polypeptides appear to block the binding of integrins, which are expressed on OCUM-2MD3 cells, to the submesothelial ECM, and consequently inhibit peritoneal implantation. The peritoneal injection of adhe-sion polypeptides may be a new therapy against the dissemination of scirrhous gastric cancer, and may be useful for the prevention of dissemination in high-risk patients. © Rapid Science Ltd.     

Establishment and characterization of αs1-casein–specific T-cell lines from patients allergic to cow’s milk: Unexpected higher frequency of CD8 T-cell lines

To study cow’s milk allergy at the cellular level, we assessed the reactivity of peripheral blood mononuclear cells from patients allergic to cow’s milk to α_s1-casein, which is one of the major allergens in cow’s milk. Proliferation of the cells to α_s1-casein activation showed a rather weak response. Therefore to understand T-cell reactivity to α_s1-casein in more detail, we prepared α_s1-casein–specific T-cell lines from patients allergic to cow’s milk and established 26 T-cell lines. These T-cell lines could be classified into three groups by analyzing their surface marker expression: those containing predominantly CD4⁺CD8^- T cells, those containing both CD4⁺CD8^- and CD4^-CD8⁺ T cells, and those containing predominantly CD4^-CD8⁺ T cells. The CD8⁺ T cells were obtained at an unexpectedly higher frequency from the patients. These T-cell lines produced interferon-γ and IL-4. These results suggest that CD8⁺ T cells specific for α_s1-casein and CD4⁺ T cells were primed by the stimulation with α_s1-casein in patients allergic to milk and that both T cells may play a key role in the onset, progression of, or recovery from cow’s milk allergy. (J ALLERGY CLIN IMMUNOL 1996;97:1342-9.)     

Pancreatoblastoma with marked elevation of serum alpha-fetoprotein

Summary The autopsy findings in a pancreatoblastoma in a 7-year-old Japanese girl is reported. The tumour was in the head and body of the pancreas, and was associated with diffuse carcinomatous peritonitis and hepatic and pulmonary metastases. There was marked elevation (more than 10000 ng/ml) of serum alpha-fetoprotein (AFP). Histopathologically the tumour was composed of solid epithelial elements with fibrous stroma, showing acinar arrangement, squamoid clusters and tubular structures. The epithelial elements contained numerous fine PAS positive granules in the cytoplasm. Immunocytochemical results suggested epithelial differentiation with positivity to alpha-1-antitrypsin (AAT), keratin, CA19-9, and AFP. No endocrine elements were recognized. Characteristic feature of this tumour are discussed and compared with prevoius reports.     

Long-term potentiation in the optic tectum of rainbow trout

We examined synaptic plasticity in the optic tectum of rainbow trout by extracellular recordings. We found that the field-excitatory postsynaptic potential in the retinotectal synapses was potentiated by repetitive stimuli of 1.0 Hz for 20 s to the retinotectal afferents. The long-term potentiation (LTP) developed slowly, and was maintained for at least 2 h. Applications of an antagonist for N-methyl-D-aspartic acid (NMDA) receptors or Mg²⁺-free saline showed that activation of NMDA receptors was required to form the LTP beyond the induction period. The present findings indicate that presynaptic stimulation in the retinotectal synapses causes LTP mediated by NMDA receptors in the optic tectum of rainbow trout.     

Identification and characterization of temperature-sensitive mild mutations in three Japanese patients with nonsevere forms of very-long-chain acyl-CoA dehydrogenase deficiency

Very-long-chain acyl-CoA dehydrogenase (VLCAD) deficiency is clinically classified into severe, intermediate, and myopathic forms. We identified mutations in three unrelated Japanese patients with VLCAD deficiency: two with the myopathic form and one with the intermediate form, all compound heterozygotes of K264E/M437V, A416T/1798delA, and P89S/IVS16-3delAA, respectively. We characterized four missense mutations, K264E, M437V, A416T, and P89S, by transisent expression analysis, using SV40-transformed fibroblasts derived from a VLCAD-null patient, as recipient cells. In transient expression of the wild-type VLCAD cDNA, VLCAD activity at 30 degrees C was higher than at 37 degrees C. Moreover, this temperature-sensitive character is more evident in all the mutant proteins tested than in wild type. Based on characterization of the five missense mutations identified in four Japanese patients, including data on one patient with the myopathic form previously reported, patients with the nonsevere forms (intermediate or myopathic forms) have missense mutations with residual activities in at least one allele. Expression analysis at 30 degrees C may be more useful for evaluating these missense mutations, compared with that at 37 degrees C.     

Effects of fluoride release from bis-GMA/TEGDMA resin regulated by gamma-methacryloxypropyltrimethoxysilane on demineralization of bovine enamel

We previously demonstrated that fluoride release from resins could be regulated by the polysiloxane coating of the fluoride additives. The present study investigated the effects of regulated fluoride release from resin on enamel demineralization in vitro. Bovine enamel cavities were restored with bis-GMA/TEGDMA resins containing 50 wt% NaF powders treated with or without gamma-methacryloxypropyltrimethoxysilane. Specimens were immersed in distilled water that was changed daily to measure the amount of fluoride released over 40 days, and thereafter subjected to pH-cycling. Microradiographic observations were performed to determine total mineral loss (AZ) and lesion depth (Ld) on the enamel. In addition, fluorine distribution was analyzed using EPMA. The resin containing untreated NaF exhibited high-rate and short-term fluoride release, whereas the resin containing treated NaF released low concentrations of fluoride over a longer period. The former showed high fluorine uptake in the adjacent enamel. In contrast, the latter showed high fluorine uptake not only in the adjacent enamel, but also in a wider area of enamel surface. The latter also showed lower AZ and Ld values in the surrounding enamel, indicating a high inhibitory effect on caries formation. Therefore, it is suggested that regulated fluoride release from the resin based on polysiloxane coating is effective in preventing caries formation.     

Neonatal impact of leukemia inhibitory factor on neurobehavioral development in rats

Cytokines have been implicated in the etiology or pathology of various psychiatric diseases of developmental origin such as autism and schizophrenia. Leukemia inhibitory factor (LIF) is induced by a variety of brain insults and known to have many influences on mature and immature nervous system. Here, we assessed the neurobehavioral and pathological consequences of peripheral administration of LIF in newborn rats. Subcutaneous LIF injection induced STAT3 phosphorylation in many brain regions and increased glial fibrillary acidic protein (GFAP) immunoreactivity in the neocortex, suggesting that LIF had direct effects in the central nervous system. The LIF-treated rats displayed decreased motor activity during juvenile stages, and developed abnormal prepulse inhibition in the acoustic startle test during and after adolescence. They displayed normal learning ability in active avoidance test, however. Brain neuronal structures and startle responses were grossly normal, except for the cortical astrogliosis during neonatal LIF administration. These results indicate that LIF induction in the periphery of the infant has a significant, but discrete impact on neurobehavioral development.