Identification of a putative G protein-coupled receptor induced during activation-induced apoptosis of T cells

During development, self-reactive immature thymocytes are clonally deleted in the thymus, a phenomenon which establishes T cell tolerance (negative selection). It has been shown that the deletion of self-reactive immature T cells in the thymus is mediated by apoptosis upon T cell receptor (TCR) engagement. Apoptosis of immature thymocytes mediated by the TCR requires the expression of a new set of genes. To define which genes are required during the TCR-mediated death of immature thymocytes, we sought to identify genes whose expression is increased during TCR-mediated cell death. Using the technique of differential mRNA display, we have identified a novel gene, TDAG8, which encodes a putative G protein-coupled receptor. The expression of TDAG8 is greatly induced upon activation of T cells by anti-TCR antibody or by phorbol 12-myristate 13-acetate plus ionomycin. The treatment of T cells with glucocorticoids also greatly induces the expression of TDAG8. In mice, TDAG8 is predominantly expressed in thymus and spleen. The tissue-specific expression of TDAG8 and the induction of its expression during cell death of T cells mediated by the TCR or glucocorticoids suggest that it may have a role in activation-induced cell death or differentiation of T cells.

Red blood cell indices and iron status according to feeding practices in infants and young children

With the electronic counters routinely used, it has become practical to determine the concentration of hemoglobin, red cell indices, and RDW concurrently in association with transferrin saturation and ferritin in accordance with feeding practices. The 1028 infants and children aged 6 to 24 months, who had been mainly admitted with acute infectious or inflammatory diseases, were divided into three groups, i.e., children who were exclusively breast-fed more than 6 months (group A), those who had been given iron-fortified formula milk since birth (group B), and those who had been given breast milk for 5-6 months and then switched to the iron-fortified formula (group C). Children with anemia comprised 34.8% (104/299) of group A, significantly more than 5.6% (34/608) of group B and 6.6% (8/121) of group C (p < 0.001, respectively). Children with MCV < 70 fl comprised 39.5% (118/299) of group A, significantly more than 7.1% (43/608) of group B and 13.2% (16/121) of group C. Out of the total 146 patients with anemia, 82.2% (n = 120) had laboratory evidence of iron deficiency, which was mostly suggested by a dietary history. The sensitivity of MCV values < 70 fl in IDA patients was 90.0%; specificity was 53.8%. The sensitivity of RDW values > or = 15% was 83.3%; specificity was 57.7%. The positive predictive value could be increased to 97.8% by combining MCV < 70 fl and RDW > or = 15%. The sensitivity of serum ferritin concentrations < 10 ng/ml was 62.4% and specificity was 100%. The sensitivity of transferrin saturation < 12% was 72.3% and specificity was 81.3%. By combining the hemoglobin with MCV and RDW in screening for iron deficiency, the diagnostic accuracy of IDA can be increased. We support the use of appropriately iron-fortified weaning foods or the routine iron supplement starting at 6 months of age in exclusively breast-fed infants.

Antisense GLUT1 RNA suppresses the transforming phenotypes of NIH 3T3 cells transformed by N-Ras

An antisense approach was attempted to investigate the role of antisense GLUT1 RNA in suppressing tumor cell phenotypes using N-ras-transformed NIH 3T3 cells. The established cell line transformed by ras showed typical biological characteristics of cancer cells, such as increased glucose transport, GLUT1 mRNA contents, and the ability to form colonies on the soft agar. In this system, the plasmids (pMAM-GLUT1(rev)) which can transcribe the antisense GLUT1 RNA were transfected and the accompanying changes in the phenotypes of the ras-transformed cells were observed. The expression of antisense GLUT1 RNA by induction with dexamethasone reduced the glucose transport by 30% (1.97 +/- 0.13 nmoles) after 4 min incubation when compared to the non-induction group of transformed cell (2.85 +/- 0.19 nmoles). Also, the number of colonies sized over 50 microns on the soft agar was reduced significantly in the antisense RNA expressing group compared to non-induction group. These results suggest that the expression of antisense GLUT1 RNA reduced the glucose transport and transforming potential in soft agar possibly by hybridization with GLUT1 mRNA in N-ras-transformed NIH 3T3 cells.

Comparison of different mechanical ventilators for patients with poliomyelitis

Poliomyelitis can affect patients with severe hypoxia and hypercapnia. Historically, most of these patients were supported by mechanical ventilation via tracheostomy. However, this procedure can lead to serious complications. Subsequently, non-invasive alternative procedures have been introduced that provide mechanical respiratory support; these include negative pressure ventilators and positive pressure ventilation via a nasal, oral, and oronasal interface. Although these ventilators are effective, various limitations have been noted. The strapless oronasal interface positive pressure ventilator appears to have the fewest limitations, and through the use of advanced dental techniques and improved dental materials, this ventilator is easily fabricated and has been noted by patients to be more comfortable.

3'-untranslated sequences mediate post-transcriptional regulation of 3-hydroxy-3-methylglutaryl-CoA reductase mRNA by 25-hydroxycholesterol

In an earlier study [Choi, Lundquist and Peffley (1993) Biochem. J. 296, 859-866], we determined that 25-hydroxycholesterol regulates 3-hydroxy-3-methylglutaryl-CoA (HMG-CoA) reductase mRNA through a post-transcriptional mechanism that requires protein synthesis. To investigate whether 3'-untranslated sequences play a role in 25-hydroxycholesterol-mediated post-transcriptional control, we ligated approx. 1400 bp of the 3'-untranslated region of HMG-CoA reductase cDNA to the coding region of human beta-globin DNA. beta-Globin-3'-untranslated reductase fusion constructs were then transiently expressed in Chinese hamster ovary fibroblasts under conditions known to regulate reductase mRNA. There were no differences in beta-globin RNA levels in transfected cells incubated with or without lovastatin, a competitive inhibitor of reductase. However, in the presence of lovastatin and an oxysterol, 25-hydroxycholesterol, beta-globin RNA levels were decreased approx. 2-fold. Inhibition of protein synthesis with cycloheximide blocked the effects of 25-hydroxycholesterol on beta-globin RNA. Moreover, replacing the 3'-untranslated sequences with 1367 bp of the simian virus 40 enhancer region eliminated the regulatory effect of 25-hydroxycholesterol. Because the fusion construct has no sterol regulatory elements necessary for transcription, our results indicate that the change in beta-globin RNA occurred at a post-transcriptional level. In addition, we have shown that the 3'-untranslated region of HMG-CoA reductase cDNA imparted oxysterol-mediated post-transcriptional regulation to beta-globin RNA, an effect that required protein synthesis.

Cyclosporin A blocks apoptosis by inhibiting the DNA binding activity of the transcription factor Nur77

Engagement of T-cell receptors (TCRs) on immature thymocytes by self-antigen-major histocompatibility complexes causes the death of self-reactive thymocytes via apoptosis, a phenomenon that establishes T-cell tolerance. Similarly, treatment of thymocytes with anti-TCR antibodies leads to TCR-mediated apoptosis, which can also be induced in T-cell hybridomas. TCR-mediated apoptosis in immature thymocytes and T-cell hybridomas requires the expression of a new set of genes. In particular, it has recently been shown that the expression of Nur77, a transcription factor which is a member of the steroid/thyroid receptor superfamily, is required for TCR-mediated apoptosis in T-cell hybridomas and perhaps in thymocytes. Cyclosporin A (CsA), an immunosuppressive drug, has been shown to interfere with clonal deletion of self-reactive T cells in vivo, partly by blocking TCR-mediated apoptosis. We report here that CsA inhibits the TCR-mediated activation of Nur77 protein in T-cell hybridomas by blocking the DNA binding activity of Nur77 protein rather than its de novo synthesis. We also show that CsA mediates its negative effects on the Nur77 DNA binding activity through the N-terminal region of the protein. This complete inhibition of Nur77 protein DNA binding activity may explain how CsA interferes with TCR-mediated apoptosis.

The second kappa B element, kappa B2, of the HLA-A class I regulatory complex is an essential part of the promoter

The MHC class I regulatory complex (CRC) contains the well characterized palindromic kappa B element, kappa B1, to which a number of nuclear factors are known to bind. This cis element plays an important role in controlling the transcription of MHC class I genes. In addition, the CRC contains a second kappa B element, kappa B2, which is located in tandem with the kappa B1 site, 5 bp upstream. In this study, from reporter gene transfection experiments, we present evidence that this kappa B2 site is as important as kappa B1 in regulating HLA-A locus transcription. Mutations introduced into either kappa B site reduced promoter activity to approximately the level obtained when the entire CRC was deleted. Electrophoretic mobility shift and supershift assays showed that the kappa B2-binding complex (BIII) contained a p65-like subunit, but apparently not the p50 subunit of NF-kappa B. Complex BIII also bound to the kappa B1 site, but the kappa B2 sequence was poorly recognized by the kappa B1-binding complex, BI, probably KBF1, the p50 homodimer. These results demonstrate that both kappa B sites are essential components of the promoter and suggest that they may function together to control MHC class I gene transcription.

The second kappa B element, kappa B2, of the HLA-A class I regulatory complex is an essential part of the promoter

The MHC class I regulatory complex (CRC) contains the well characterized palindromic kappa B element, kappa B1, to which a number of nuclear factors are known to bind. This cis element plays an important role in controlling the transcription of MHC class I genes. In addition, the CRC contains a second kappa B element, kappa B2, which is located in tandem with the kappa B1 site, 5 bp upstream. In this study, from reporter gene transfection experiments, we present evidence that this kappa B2 site is as important as kappa B1 in regulating HLA-A locus transcription. Mutations introduced into either kappa B site reduced promoter activity to approximately the level obtained when the entire CRC was deleted. Electrophoretic mobility shift and supershift assays showed that the kappa B2-binding complex (BIII) contained a p65-like subunit, but apparently not the p50 subunit of NF-kappa B. Complex BIII also bound to the kappa B1 site, but the kappa B2 sequence was poorly recognized by the kappa B1-binding complex, BI, probably KBF1, the p50 homodimer. These results demonstrate that both kappa B sites are essential components of the promoter and suggest that they may function together to control MHC class I gene transcription.

Effect of sex hormones on lipid peroxidation in rat liver

The role of sex hormones in hepatic lipid peroxidation, and in hepatic aldehyde oxidase and xanthine oxidase activities were investigated using rat liver homogenates. It was observed that male rat had a significantly greater content of malondialdehyde in liver than female. Among the sex hormones tested, estradiol, one of female hormones, markedly inhibited the formation of lipid peroxides in liver tissues in vitro. Especially, the inhibitory effect of estradiol appeared more remarkably in Fe+2-induced lipid peroxidation. The hepatic xanthine oxidase activity was decreased about 15% by 10(-6) M estradiol, whereas, the aldehyde oxidase activity was almost completely disappeared at the same concentration of estradiol. It implies that sex differences in lipid peroxidation is attributed to the suppression of free radical generating system by estradiol.

Inhibition of protein synthesis in baby-hamster kidney cells blocks oxysterol-mediated suppression of 3-hydroxy-3-methylglutaryl-CoA reductase mRNA at a post-transcriptional level

The effects of the protein-synthesis inhibitor cycloheximide on 25-hydroxycholesterol-mediated suppression of 3-hydroxy-3-methylglutaryl-CoA (HMG-CoA) reductase mRNA levels were evaluated in the baby-hamster kidney cell line C100. Cells cultured in medium supplemented with delipidized fetal bovine serum and 25 microM lovastatin for 12-24 h had a 5-fold higher level of HMG-CoA reductase mRNA than cells grown in medium supplemented with non-delipidized fetal bovine serum (FBS). The higher level was due to increased transcription, as determined by run-on assays with isolated nuclei. Addition of 25-hydroxycholesterol to lovastatin-treated cells lowered HMG-CoA reductase mRNA levels within 4 h of treatment to those of cells grown in FBS-supplemented medium. This decrease was due in part to a decrease in gene transcription. Cycloheximide added in conjunction with 25-hydroxycholesterol to lovastatin-treated cells blocked the suppression of mRNA levels, but did not block oxysterol-mediated suppression of transcription. In addition, cycloheximide added to cells grown in FBS-supplemented medium rapidly increased mRNA levels by 10-fold relative to untreated cells, with no comparable increase in transcription. No comparable increase in either the mRNA level or rate of transcription for beta-actin was observed under such conditions. These results indicate that cycloheximide specifically stabilizes HMG-CoA reductase mRNA in the presence of oxysterols and suggests that continuous synthesis of a short lived protein regulator is required for oxysterol-mediated suppression of HMG-CoA reductase mRNA at a post-transcriptional level.

Hyperkalemia due to hyporeninemic hypoaldosteronism with liver cirrhosis and hypertension

A 49-year-old man with liver cirrhosis and hypertension was found to have hyperkalemia out of a degree of renal insufficiency and metabolic acidosis with low to normal anion gap, aggravated by volume contraction with diarrhea and medications (captopril, spironolactone and atenolol) interfering with potassium homeostasis. Plasma renin activity and serum aldosterone levels of this patient on a regular diet after discontinuation of medications were very low compared to those of five other cirrhotic patients with normokalemia as controls. Also, the renin-aldosterone stimulation testing on this patient performed by sodium restricted diet and furosemide, upright position and by angiotensin converting enzyme inhibition (captopril, 50 mg) showed the blunted renin and aldosterone responses to each of these stimuli, almost no changes from baseline renin and aldosterone levels, it was concluded that the underlying defect responsible for hyperkalemia in this case was hyporeninemic hypoaldosteronism and this was aggravated by other factors or drugs affecting potassium homeostasis.

The fluid dynamic effect on protein adsorption in left ventricular assist devices

Plasma protein adsorption onto an artificial surface is strongly influenced by not only the surface characteristics of materials, but also by the fluid dynamics inside the blood pump, and it would influence subsequent platelet adhesion or activation, which plays a major role in the initiation of thrombus formation at the blood-material interface in vivo. In vitro flow visualization of an electrohydraulic LVAD was performed by a video camera (CCD, Hitachi) and an image processor (PC VISION PLUS) with an IBM PC. The electrohydraulic LVADs were implanted in mongrel dogs of approximately 20 kg. The authors sectioned the blood contacted ventricle after animal death according to the level of shear rate. Because analysis of adsorbed protein might be influenced by the size of the ventricle segment, the number of segments was limited to eight per ventricle. Platelet adhesion and its morphology were observed by scanning electron microscopy (SEM). Adsorbed plasma proteins (fibrinogen, albumin, and IgG) on each segment were quantified by enzyme linked immunosorbent assay (ELISA). The specimens were soaked in 2% (wt/vol) SDS/PBS for 2 days and the released protein concentration assessed. A well developed large vortex was observed at the center of the artificial ventricle. Polyurethane blood pumps displayed different degrees of protein adsorption and subsequent platelet adhesion on each segment.

Effects of Temperature on Two Psychrophilic Ecotypes of a Heterotrophic Nanoflagellate, Paraphysomonas imperforata

Two different psychrophilic types of the heterotrophic nanoflagellate Paraphysomonas imperforata were isolated from Newfoundland coastal waters and the Arctic Ocean. When fed bacteria without food limitation, both isolates were able to grow at temperatures from -1.8 to 20°C, with maximum growth rates of 3.28 day -1 at 15°C and 2.28 day -1 at 12.3°C for the Newfoundland and the Arctic isolates, respectively. Ingestion rates increased with temperature from 14 to 62 bacteria flagellate -1 h -1 for the Newfoundland isolate and from 30 to 99 bacteria flagellate -1 h -1 for the Arctic isolate. While temperature did not affect cell yields (number of protozoa produced divided by number of bacteria consumed), it affected flagellate sizes. This differential effect of temperature on cell yield and cell size resulted in a changing gross growth efficiency (GGE) in terms of biovolume; colder temperatures favored higher GGEs. The comparison of Q 10 values for growth rates and ingestion rates between the isolates shows that the Arctic isolate is better adapted to extremely cold temperature than the Newfoundland isolate. At seawater-freezing temperature (-1.8°C), the estimated maximum growth rates and maximum ingestion rates are 0.81 day -1 and 30 bacteria flagellate -1 h -1 for the Arctic isolate and 0.54 day -1 and 12 bacteria flagellate -1 h -1 for the Newfoundland isolate. Our findings about psychrophilic nanoflagellates fit the general characteristics of cold-water-dwelling organisms: reduced physiological rates and higher GGEs at lower temperatures. Because of the large and persistent differences between the isolates, we conclude that they are ecotypes adapted to specific environmental conditions.

Development of a new moving-actuator type electromechanical total artificial heart

A new type of electromechanical total artificial heart based on a moving-actuator mechanism was developed to decrease the total pump size and to improve the fitting characteristic of the pump to atrial remnants and arterial vessels. The blood pump consists of three major parts: right and left blood sacs and a moving pump actuator between two sacs. The total weight is 810 g and the volume of the pump is 770 ml. The actuator rolls back and forth on a circular track, producing alternating blood ejection. The pump performance was evaluated in mock circulation and animal implant experiments. The pump was implanted for 100 h in a calf (approximately 100 kg) with a stable hemodynamic state until accidental (electrical short circuit) death.

A moving-actuator type electromechanical total artificial heart--Part II: Circular type and animal experiment

A new type of electromechanical total artificial heart (TAH) based on circular rolling-cylinder mechanism was developed to overcome critical problems in motor-driven artificial hearts such as large size and difficulties in fitting the heart to atrial remnants and arterial vessels. Its performance and reliability were evaluated in mock circulation and in an animal implant experiment. The total weight and volume of the pump is 650 g and 600 mL, respectively. This new pump was implanted in a calf for total heart replacement and 96 h of survival was achieved. The whole system, including pump, controller, and control algorithm performed well enough to improve the prospect of eventual clinical application of our TAH system.

A tether-free, moving actuator total artificial heart

An electromechanical moving-actuator TAH was developed and implanted for 5 days in a calf experiment. The efficiency and durability were further improved using pendulous motion of the actuator. This new pendulum pump has a circular motion produced by gear mechanisms connected to the motor. It has a height (from valves to housing bottom) of 7 cm and centrally directed inlets and outlets for good fittability. Active filling (-10 mmHg) inside inner blood sacs was produced by the suction effects of the outer sacs attached to a moving actuator. Two acute animal experiments were performed using the pendulum pump with a Coridale sheep (50 kg weight), and a male calf (70 kg weight). A test was made of 30 minutes of tether-free operation of the implanted pendulum pump inside the small chest of the calf. The pump shows the engineering feasibility of the implantable electrical TAH inside a human chest cavity.

A reduction factor in goodness-of-fit and independence tests for clustered and weighted observations

Situations often arise in a large-scale household survey where a complex probability sample of clusters rather than of individuals is drawn from a large population. Typically, the clusters of such complex samples include a number of correlated members. The responses of these members are then weighted to obtain estimates for the population. Such weighted data are commonly published by the National Center for Health Statistics and other U.S. federal agencies. Frequently, problems arise when such data are tested by usual chi-square test statistics for goodness of fit or independence. Researchers have discovered that the usual chi-square tests provide spuriously inflated results when applied to cluster samples and that new methods are required to correct such problems. This paper proposes a strategy for a goodness-of-fit or independence test based on correlated and weighted data arising in cluster samples, and provides a factor that validly reduces the inflation of the usual chi-square statistics. This method is applied to the chronic condition data collected from the St Paul-Minneapolis, Minnesota, primary sampling unit (PSU) during the 1975 National Health Interview Survey (NHIS). This analysis, together with simulation studies presented elsewhere, provides evidence that the usual chi-square statistics from such data can be corrected for the impacts of clustering and weighting by use of the proposed reduction factor.

Effects of Fixation on Cell Volume of Marine Planktonic Protozoa

The effects of fixation on the cell volume of marine heterotrophic nanoflagellates and planktonic ciliates were investigated. Decreases in cell volume depended on the combination of the protozoan taxa and the particular fixative. For a particular fixative and protozoan species, degree of shrinkage was independent of physiological state. The volume of fixed cells was found to be approximately 20 to 55% lower than the cell volume of live organisms. For the heterotrophic microflagellates, the fixatives ranked, in order of decreasing effect on cell volume, as glutaraldehyde, formaldehyde, acid Lugol's solution, and modified van der Veer solution. With oligotrichous ciliates and a tintinnid ciliate, formaldehyde caused less shrinkage than glutaraldehyde or acid Lugol's solution. With the aldehyde fixatives, the microflagellates were found to shrink more than the ciliates. Differential effects of fixation on cell volumes may result in an underestimation of the biomass of certain protozoan taxa in natural samples.