Iron deficiency down-regulates the Akt/TSC1-TSC2/mammalian Target of Rapamycin signaling pathway in rats and in COS-1 cells

Iron deficiency (ID) is one of the most commonly known forms of nutritional deficiencies. Low body iron is thought to induce neurologic defects but may also play a protective role against cancer development by cell growth arrest. Thus, ID may affect cellular pathways controlling cell growth and proliferation, the mechanism of which is still not fully understood. The serine/threonine protein kinase Akt and its downstream target, the mammalian Target of Rapamycin (mTOR), is known to play a crucial role in the regulation of cell growth and survival. Therefore, we hypothesized that Akt/mTOR pathway could be influenced by ID. Three-week-old male Wistar-strain rats were divided into 3 groups and the 2 groups had free access to a control diet (C group) or an iron-deficient diet (D group). The third group (PF group) were pair-fed the control diet to the mean intake of the D group. After 4 weeks, rats were killed and their brains were sampled. In separate experiments, COS-1 cells were cultured with or without the iron chelator deferoxamine. Western blots of brain samples and COS-1 lysates were used to analyze the expression and phosphorylation state of Akt, TSC2, mTOR, and S6 kinase proteins implicated in the Akt/mTOR pathway. Using 2 different ID models, we show for the first time that iron deficiency depresses Akt activity in rats and in COS-1 cells, leading to a decrease in mTOR activity.     

Effects of glycyrrhetinic acid on aminonucleoside nephrosis in rats

The effects of glycyrrhetinic acid (GA), an aglycon of glycyrrhizin extracted from the roots of Glycyrrhizae radix, on puromycin aminonucleoside (PA) nephrosis were studied in rats. Urine protein excretion in female rats (130g–150g) receiving PA (50 mg/kg) alone was significantly elevated on the 2nd day after injection of PA and reached a peak on the 14th day. Urinary protein on the 14th day was reduced to 74% in animals treated with GA (20 mg/kg) starting on the 2nd day after injection of PA. The increase in serum cholesterol and the decrease in serum protein were also suppressed by GA. Observation by electron microscopy revealed that the degree of abnormality in glomerular epithelial cells, i.e. loss or fusion of foot processes, was lower in the rats treated with GA after PA injection than in the rat treated with PA alone. Moreover, pretreatment with GA did not suppress urinary protein excretion but when it was given at the same time as PA and after PA a significant decrease in urinary protein excretion was observed. Correspondence to: H. Abe at the above address     

N-Glycosylation contributes to the limited cross-reactivity between hemagglutinin neuraminidase proteins of human parainfluenza virus type 4A and 4B

cDNAs encoding human parainfluenza virus type 4B (hPIV-4B) hemagglutinin neuraminidase (HN) protein were cloned and the nucleotide sequences were determined. A high degree of identity (81.4%) was observed between the nucleotide sequences of hPIV-4A and -4B HN proteins, and an 87.3% identity was found between the deduced amino acid sequences. This degree of identity is considered to be greater than immunological similarity between hPIV-4A and -4B HN proteins determined using monoclonal antibodies. To elucidate the causes of the antigenic difference between HN proteins of hPIV-4A and -4B, we constructed three cDNAs of hPIV-4B HN whose potential N-glycosylation sites were partially or completely the same as in hPIV-4A HN cDNA. We compared the antigenicity of the expressed wild-type and mutant proteins, and found that the antigenicities of the mutant hPIV-4B HN proteins were more similar to the hPIV-4A HN protein than to the non-mutant hPIV-4B HN protein. This study indicated that the antigenic diversity between hPIV-4A and -4B was partly caused by deletion or creation of glycosylation sites, showing that the point mutations resulting in deletion or creation of glycosylation sites is one of the initial steps leading to the division of virus into subtypes. Received: 21 January 2000     

Recombinant Sendai viruses with L1618V mutation in their L polymerase protein establish persistent infection, but not temperature sensitivity

The Sendai virus pi strain (SeVpi) isolated from cells persistently infected with SeV shows mainly two phenotypes: (1) temperature sensitivity and (2) an ability of establishing persistent infection (steady state). Three amino acid substitutions are found in the Lpi protein and are located at aa 1088, 1618, and 1664. Recombinant SeV(Lpi) (rSeV(Lpi)) having all these substitutions is temperature sensitive and is capable of establishing persistent infection (steady state). rSeVs carrying the fragment containing L1618V show both phenotypes. rSeV(L1618V), in which leucine at aa 1618 is replaced with valine, has the ability of establishing persistent infection, but is not a temperature-sensitive mutant, indicating that the ability of a virus to establish persistent infection can be separated from temperature sensitivity. The amino acid change at 1618(L-->V) coexisting with aa 1169 threonine is required for acquirement of a temperature-sensitive phenotype. Three amino acid substitutions are also found in the Ppi protein, but rSeV(Ppi) does not show these phenotypes.     

Functional regulation by dopamine receptors of serotonin release from the rat hippocampus: in vivo microdialysis study

The functional regulation by dopamine (DA) receptors of serotonin (5-HT) release from the rat hippocampus was investigated by use of in vivo microdialysis. Dialysate 5-HT levels were reduced by co-perfusion of 10 M tetrodotoxin (TTX) and were elicited by K⁺ (60 and 120 mM) stimulation in a concentration-dependent manner. Local perfusion (10 M) and peripheral administration (20 mg/kg, i.p.) of fluoxetine produced increases in 5-HT levels. These results indicate that the spontaneous 5-HT levels in the rat hippocampus can be used as indices of neuronal origin from the serotonergic nerve terminals. The nonselective dopamine (DA) receptor agonist apomorphine (1, 10 and 100 M), when perfused through the probe over a period of 40 min, increased 5-HT release in a concentration-dependent manner. Apomorphine-induced (100 M) increases in 5-HT release was abolished by pretreatment with the selective D₂ receptor antagonist, S(–)-sulphide (1 and 10 M), but not prevented by pretreatment with the selective D₁ receptor antagonist, R(+)-SCH-23390 (R(+)-7-chloro-8-hydroxy-3-methyl-l-phenyl-2,3,4,5-tetrahydro-1H-3-benzazepine) (1 M). S(–)-Sulpiride and R(+)-SCH-23390 by themselves did not alter the spontaneous 5-HT levels. The 5-HT release was elevated by perfusion of the selective DA reuptake inhibitor GBR 12909 (1-[2-[bis(4-fluorophenyl)methoxy]ethyl]-4-[3-phenylpropyl]piperazine)(1, 10 and 100 M), indicating the possibility of not only exogenous but also endogenous DA-mediated facilitatory effects on 5-HT release in vivo. The 5-HT release was also elevated by perfused (±)-PPHT ((±)-2-(N-phenylethyl-N-propyl)-amino-5-hydroxytetralin)(1, 10 and 100 M), the selective D₂ receptor agonist, in a concentration-dependent manner. On the other hand, (±)-PPHT (100 M) failed to increase 5-HT release in catecholamine (CA)-lesioned rats pretreated with 6-hydroxydopamine (6-OHDA)(200 g/rat, i.c.v.). The (±)-PPHT-induced (100 M) increase in 5-HT release was prevented not only by pretreatment with 10 M S(–)-sulphide but also by pretreatment with the ₂-adrenoceptor antagonist idazoxan (10 M). These findings suggest that the functional regulation of 5-HT release via D₂ receptors exists in the rat hippocampus. Furthermore our results indicate that the facilitatory effect of 5-HT release via D₂ receptors may be mediated indirectly by noradrenergic neurons, but not mediated directly through D₂ receptors located on serotonergic nerve terminals.     

Radiographic Diagnosis of Early Colorectal Cancer, with Special Reference to the Superficial Type of Invasive Carcinoma

The possibility of radiographically diagnosing carcinoma with submucosal involvement (invasive carcinoma) is discussed based on 119 invasive carcinomas of the large bowel that had been treated surgically and colonoscopically over a period of 9 years (1989—1997) at the Cancer Institute Hospital in Tokyo. Of these lesions, 38 were superficial-type invasive carcinoma, accounting for 31.9% (38/119) of all invasive colorectal carcinomas, including 36 lesions (94.7%, 36/38) of types IIa and IIa+IIc and 2 lesions (5.3%, 2/38) of type IIc+IIa. No pure type IIc was seen. The radiographic images obtained were correlated with macroscopic findings and analyzed in terms of visualization of the lesion's contour, central depression, converging folds, and basal indentation. A definitive diagnosis of superficial invasive carcinoma can be made radiographically if a lesion measures 10 mm and reveals moderate to severe basal indentation in a complete or nearly complete profile radiographic image. Attention should be paid to the presence of superficial-type advanced carcinomas measuring 10 mm or less, which is not infrequently experienced in Japan. Polypoid invasive carcinoma can be definitively diagnosed in the same way with much more certainty than can the superficial type because few polypoid advanced carcinomas are less than 20 mm. The size and the radiographic sign of the basal indentation are the most important indicators for the diagnosis of invasive carcinoma. E-pub: 27 July 2000     

Factors associated with home environmental problems among community-living older people

Purpose : This paper describes the types of difficulties older people have with their home environments and the factors associated with having such difficulties. Method : Data were used from 296 study participants of the University at Buffalo's Consumer Assessments Study that examines the home modification needs and environmental difficulties of older people. A combination of socio-demographic variables, health and functional status indicators and measures of psychosocial well-being were used to predict environmental problems. Results : An average of 13 problems with the environment that posed as a barrier to safe and independent performance was observed in homes. It was found that most difficulties occurred in bathrooms, kitchens, bedrooms and access to entryways and rooms. Hierarchical multiple regression analysis showed that having home environmental problems was most strongly associated with younger age, being female, being of minority status, having pain, and greater physical disability. Conclusion : The findings show that a combination of conditions that include demographic and functional conditions place older people at risk for problems with the home environment that impede performance of daily living activities.     

Evaluation of community-acquired pneumonia guidelines of Japanese Respiratory Society: differentiation of atypical pneumonia and bacterial pneumonia]

To evaluate the usefulness of differentiation of atypical pneumonia and bacterial pneumonia in the community-acquired pneumonia guidelines of the Japanese Respiratory Society, we investigated 124 cases of three atypical pneumonias (Mycoplasma pneumonia, 62 cases; Chlamydia pneumoniae pneumonia, 46 cases; Chlamydia psittaci pneumonia, 13 cases) and 403 cases of bacterial pneumonia at our hospital over seven years. Overall, the sensitivity and specificity of the criteria in the guideline were 70.4% and 91.8%, respectively. High accordance was recognized in patients under 60 years old with atypical pneumonia. Items in the criteria that included subjective factors were considered inassessable. We found that the differentiation of pneumonias in the guideline is useful for the diagnosis of atypical pneumonia among younger patients, but it should be concise and objective. We therefore propose that the criteria would be more effective if they consisted of only 4 items: age under 60 years, no underlying disorders, presence of stubborn dry cough, and normal peripheral white blood cell count.     

New Approach to Eliminate HLA Class I Antigens from Platelet Surface without Cell Damage: Acid Treatment at pH 3.0

A new method was studied for eliminating HLA class I antigens from the surface of platelets without damaging the cells. Platelets were exposed to an acid solution (pH 3.0) to eliminate the antigenicity of HLA class I antigens. The reduction in antigenicities of HLA class I common antigen and individual HLA class I antigens by acid treatment was marked. Patients' sera which contained multispecific HLA antibodies reacted with PBS-treated platelets, but not with acid-treated platelets. No changes were observed in the antigenicities of glycoprotein Ib or glycoprotein IIb/IIIa. The viability of acid-treated platelets was 83%. Ultrastructural investigations revealed no significant difference between the PBS-treated platelets and acid-treated platelets. The platelet function studies showed that the aggregation of acid-treated platelets induced by various agonists was only slightly reduced compared with PBS-treated platelets. We propose that acid-treated platelets are promising for clinical use in patients refractory to platelet transfusions and may be superior to chloroquine-treated platelets for analysis of the specificity of antiplatelet antibodies.