Increase in human placental glucose transporter-1 during pregnancy

Glucose transporter-1 (GLUT1) has been found in high abundance in human placentas. The purpose of this study was to analyze the changes in the level of GLUT1 during pregnancy. We have analyzed the gestational changes in human placental GLUT1 by [3H]cytochalasin B binding assay, immunoblot analysis and Northern blot analysis. Levels of [3H]cytochalasin B binding to placental membrane in pregnancy at 7-10, 18-20 and 38-40 weeks were 4.2 +/- 0.47, 5.2 +/- 0.46 and 7.2 +/- 0.40 (mean +/- SEM, N = 4) mumol/kg protein, respectively. Amounts of 49-kD and 60-kD proteins detected in immunoblot analysis increased during pregnancy in parallel with [3H]cytochalasin B binding to placental membrane. The GLUT1 mRNA levels also increased during pregnancy. Immunohistochemical examination showed that GLUT1 was localized in the plasma membranes of trophoblast cells. These findings showed that the GLUT1 level increased during pregnancy in human placentas and suggest that GLUT1 may play an important role in fetal development.

Modeling of controlled release of aspirin derivatives from human erythrocytes

The transport of aspirin (ASP) and its derivatives (m- or p-acetoxybenzoic acid (m- or p-AcOHBA), o-propionyloxybenzoic acid (PrOHBA), o-butyryloxybenzoic acid (BuOHBA), o-acetoxyhippuric acid (AcOHPA), and o-acetoxy-N-benzoyl-beta-alanine (AcONBA)) through human erythrocyte membrane was investigated. ASP derivatives were transported into the erythrocytes where they were hydrolyzed and then released, although the derivatives varied in the rate of transport. In different binding positions, the hydrolyzed derivatives were released rapidly in the order of p- > m- > o-AcOHBA (ASP). The rates of derivatives were accelerated by lengthening of the side chain of the acetoxyl group (BuOHBA > PrOHBA > ASP). The rate of release of o-, m- or p-AcOHBA, BuOHBA and PrOHBA was related to hydrolysis rate in erythrocytes but not to partition coefficient (log P). In different amino acids in a carboxyl group of ASP, the release of AcONBA was slower and about 2 h was required to attain equilibrium. The release of AcOHPA was also slower and increased gradually during an incubation of 3 h. The rate of release of AcOHPA and AcONBA was not related to hydrolysis rate in the erythrocytes. The rates were equivalent values with the predicted values calculated by log P of tested drugs. It was suggested from these results that ASP derivatives were able to control the release from human erythrocytes.

[Acute lymphoblastic leukemia accompanied by severe hypercalcemia; successful treatment with bisphosphonate]

A 62-year-old woman was admitted to the hospital because of bone pain. Laboratory data showed blasts in the peripheral blood, hypercalcemia (corrected calcium 15.1 mg/dl) and an increased level of parathyroid hormone related-protein (PTHrP). Bone marrow aspiration revealed increased lymphoblasts (96.5%), indicating acute lymphoblastic leukemia (ALL, L1). Subsequent radiological examination disclosed bone infiltration of ALL. Although the hypercalcemia was successfully treated with bisphosphonate, the PTHrP level remained high. After chemotherapy, the blasts in the peripheral blood disappeared and the PTHrP level normalized. We hypothesize that in the present case the production of PTHrP by lymphoblasts resulted in the hypercalcemic state. Although ALL is rarely accompanied by hypercalcemia, this case might help us to understand the relationship between ALL and hypercalcemia.

HCV RNA monitoring for tailored regimens of interferon therapy in hepatitis C

Sustained non-viraemia is prerequisite for a virological cure of hepatitis C virus (HCV) disease. We monitored serum HCV RNA in our patients during interferon therapy and for 6 months of follow-up. The rate of sustained responders (RNA-negative at the end of follow-up) differed significantly by whether or not RNA became sero-negative within 24 weeks of the initiation of therapy (71% vs 7%); and also by whether or not the RNA-seronegativity lasted for 12 weeks during therapy (88% vs 11%). Thus, by monitoring viraemia in individual patients, we can tailor the duration of therapy and minimize waste of interferon.

Tetrodotoxin-resistant persistent Na+ current underlying pacemaker potentials of fish gonadotrophin-releasing hormone neurones

1. Gonadotrophin-releasing hormone (GnRH)-immunoreactive terminal nerve (TN) cells show endogenous regular beating discharges, which may be related to their putative neuromodulator functions. The ionic mechanism underlying the pacemaker potential was studied using intracellular and patch-pipette current clamp recordings from a whole brain in vitro preparation of a small fish brain. 2. The pacemaker potentials were resistant to 1.5-3 microM tetrodotoxin (TTX) and were not affected by Ca2+ channel blockers (amiloride, Ni2+, Co2+, Cd2+) or in Ca(2+)-free solution. In contrast, the pacemaker potentials were readily blocked by substituting tetramethylammonium or choline for Na+ in the perfusing solution, and the resting membrane potential became more hyperpolarized than the control level. 3. The present results suggest that the TTX-resistant persistent Na+ current, INa(slow), supplies the persistent depolarizing drive and plays an important role in the generation of pacemaker potentials in TN GnRH cells.

Mitochondrial diabetes mellitus--glucose-induced signaling defects and beta-cell loss

Japanese diabetic patients whose mothers were also diabetic were screened, using peripheral leukocytes, for an A to G transition at nucleotide pair 3243 of the mitochondrial gene, a tRNA(Leu)(UUR) mutation. This mutation was identified in four pedigrees from among 300 unrelated patients. Diabetes mellitus cosegretated with the mutation, except in 1 young subject, and was maternally inherited. Long-term follow-up revealed that the underlying disorder in affected members is a progressive impairment of insulin secretion. In accord with this finding, this mutation was found to be highly prevalent in a subset of diabetes mellitus called slowly progressive IDDM; the mutation was identified in 3 of 27 Japanese patients enrolled in the prospective study of islet cell antibody (ICA)-positive, initially non-insulin-dependent diabetic patients, who are very likely to become insulin dependent in several years. The histologic characteristics of slowly progressive IDDM include loss, though incomplete, of pancreatic beta-cells. Mitochondrial gene defects in beta-cells could therefore cause glucose-induced signaling defects as well as beta-cell loss, which explains the wide range of diabetic phenotypes, from NIDDM phenotype to IDDM, in patients with this mitochondrial gene mutation.

Isolation of a cDNA clone encoding a novel membrane protein expressed in lymphocytes

By subtractive hybridization using single-stranded phagemids with directional inserts, we isolated a mouse cDNA clone, LSM-1, from temperature-sensitive Abelson virus-transformed immature B cells whose differentiation was being induced after the shift from the permissive (35 degrees C) to the non-permissive temperature (39 degrees C). LSM-1, which encodes an as yet unknown peptide of 197 amino acids, has a putative signal sequence and a trans-membrane region, and is expressed in B- and T-cell lines, in spleen, thymus, and bone marrow of adult mice, and in embryos.

A new yeast gene, HTR1, required for growth at high temperature, is needed for recovery from mating pheromone-induced G1 arrest

A new temperature-sensitive mutant of Saccharomyces cerevisiae was isolated. Arrested cells grown at the nonpermissive temperature were of dumb-bell shape and contained large vacuoles. A DNA fragment was cloned based on its ability to complement this temperature sensitivity. The HTR1 gene encodes a putative protein of 93 kDa without significant homology to any known proteins. The gene was mapped between ade5 and lys5 on the left arm of chromosome VII. The phenotype of the gene disruptant appeared to be strain-specific; disruption of the gene in strain W303 caused the cells to become temperature sensitive. The arrested phenotype here was similar to that of the original ts mutant and cells in G2/M phase predominated at high temperature. Another disruptant in a strain YPH background grew slowly at high temperature due to slow progression through G2/M phase, and morphologically abnormal (elongated) cells accumulated. A single-copy suppressor that alleviated the temperature-sensitive defects in both strains was identified as MCS1/SSD1. The wild-type strains W303 and YPH are known to carry defective MCS1/SSD1 alleles; hence HTR1 may function redundantly with MCS1/SSD1 to suppress the temperature-sensitive phenotypes. In addition, based on a halo bioassay, the disruptant strains appeared to be defective in recovery from, or adaptive response to G1 arrest mediated by mating pheromone, even at the permissive temperature. Thus the gene has at least two functions and is designated HTR1 (required for high temperature growth and recovery from G1 arrest induced by mating pheromone).

Expression of the interleukin-6 (IL-6), IL-6 receptor, and gp130 genes in acute leukemia

Expression patterns of interleukin-6 (IL-6), IL-6 receptor (IL-6R), and gp130 genes in 39 patients with acute myeloid leukemia (AML), in 23 patients with acute lymphoblastic leukemia (ALL), and in 7 patients with acute mixed lineage leukemia (AMLL) were studied by quantitative reverse transcriptase-polymerase chain reaction. Significant levels of IL-6 were expressed in 8 (21%) of 39 AML patients and in 2 (29%) of 7 AMLL patients, whereas in ALL, the expression of IL-6 was almost negligible. IL-6R was expressed in all patients with AML and AMLL, whereas only half of ALL patients expressed low levels of IL-6R as compared with those with AML and AMLL. However, gp130 was ubiquitously expressed in all the leukemia patients, and there was no significant difference in gp130 expression among AML, ALL, and AMLL. Significant correlation was observed between the expression of IL-6R and gp130 in AML. When tested for in vitro response to IL-6, the leukemic cells from 3 of 7 AML, none of 3 ALL, and both of 2 AMLL patients significantly responded to IL-6, showing the correlation between the expression levels of IL-6R and gp130 and the responsiveness of leukemic cells to IL-6. These results showed that quantitation of IL-6R and gp130 expression by reverse transcriptase-polymerase chain reaction is useful for the rapid prediction of the responsiveness of leukemic cells to IL-6, especially in cases of administration of IL-6.

NIDDM--genetic marker; glucose transporter, glucokinase, and mitochondria gene

Candidate genes for NIDDM have been screened in Japanese. Mutations in the glucokinase gene were found in apparent late-onset NIDDM patients as well as in MODY patients. Clinical characteristics in the subjects with glucokinase gene mutations are similar to those in Caucasian subjects; diabetes mellitus is generally mild and some patients actually remain as having impaired glucose tolerance. Of great interest is that all affected subjects show blunted insulin secretion response to the glucose challenge, which is most commonly observed in Japanese NIDDM patients. Thus, it is possible that impairment in the regulation of glucokinase gene expression or its enzyme activity is associated with at least some Japanese NIDDM patients, though the prevalence of the mutations in the coding region is relatively low. In contrast, a mitochondrial tRNA(Leu(UUR)) gene mutation at np 3243 appears to be much more common, and diabetes due to this mutation has a progressive nature. Insulin secretory capacity progressively decreases, eventually reaching an insulin-dependent state in most patients. A surprising result is that this gene mutation is often observed in ICA-positive IDDM patients who were initially non-insulin-dependent, so called slowly progressive IDDM patients. These results suggest that the mitochondrial gene mutation may cause beta cell loss in addition to defects in glucose-induced signaling in pancreatic beta cells, which explains that the mitochondrial gene mutation manifests a wide range of diabetic phenotypes, from NIDDM to IDDM.

[Effect of reperfusion therapy on the prognosis of acute myocardial infarction complicated by left heart failure: prediction based on the acute course of left ventricular heart failure]

This study evaluated the correlation between the acute course and prognosis of patients with acute myocardial infarction complicated by heart failure. Heart failure was defined as a mean pulmonary capillary wedge pressure equal to or greater than 20 mmHg with radiographic evidence of pulmonary congestion during hospitalization in the coronary care unit. A total of 77 heart failure patients underwent primary percutaneous transluminal coronary angioplasty or thrombolysis. Twelve patients who died within the first 3 days (group I) had a higher incidence of unsuccessful reperfusion (50 vs 19%, p < 0.05) and cardiogenic shock (64 vs 4%, p < 0.01), compared with the 65 patients who survived at least the initial 4 days (group II). These 65 patients were classified into three subgroups according to the course of heart failure: early regression type (group IIA, n = 38); prolonged type (group IIB, n = 18); delayed-onset type (group IIC, n = 9). Patients in group IIB had a higher incidence of multivessel disease than group IIA. Patients in group IIC had a higher incidence of unsuccessful reperfusion. Cardiac index in group IIB was lower than in group IIA (2.50 +/- 0.70 vs 1.91 +/- 0.39 l/min/m2). Changes in left ventricular ejection fraction were 4.1 +/- 9.2% in group IIA, -6.6 +/- 16.8% in group IIB, and 0.9 +/- 7.3% in group IIC. The hospital mortality rate was 0% in group IIA, 11% in group IIB, and 33% in group IIC, the reinfarction rate was 0, 17 and 22%, and sustained arterial patency was demonstrated in 81, 62 and 43%, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Replacement of both tryptophan residues at 388 and 412 completely abolished cytochalasin B photolabelling of the GLUT1 glucose transporter

A mutated GLUT1 glucose transporter, a Trp-388, 412 mutant whose tryptophans 388 and 412 were both replaced by leucines, was constructed by site-directed mutagenesis and expressed in Chinese hamster ovary cells. Glucose transport activity was decreased to approx. 30% in the Trp-388, 412 mutant compared with that in the wild type, a similar decrease in transport activity had been observed previously in the Trp-388 mutant and the Trp-412 mutant which had leucine at 388 and 412 respectively. Cytochalasin B labelling of the Trp-388 mutant was only decreased rather than abolished, a result similar to that obtained previously for the Trp-412 mutant. Cytochalasin B labelling was finally abolished completely in the Trp-388, 412 mutant, while cytochalasin B binding to this mutant was decreased to approx. 30% of that of the wild-type GLUT1 at the concentration used for photolabelling. This level of binding is thought to be adequate to detect labelling, assuming that the labelling efficiency of these transporters is similar. These findings suggest that cytochalasin B binds to the transmembrane domain of the glucose transporter in the vicinity of helix 10-11, and is inserted covalently by photoactivation at either the 388 or the 412 site.

Immunohistochemical double-labeling study of gonadotropin-releasing hormone (GnRH)-immunoreactive cells and oxytocin-immunoreactive cells in the preoptic area of the dwarf gourami, Colisa lalia

The distribution of gonadotropin-releasing hormone (GnRH)-immunoreactive (ir) cells in the preoptic area (POA) of the dwarf gourami, Colisa lalia, was immunohistochemically studied. These neurons form cell columns on both sides of the common ventricle, and their axons project to the pituitary gland by forming distinct bundles. Also examined was the distribution of isotocin (IST) cells in the POA by using an anti-oxytocin (OXT) serum which has been proven to crossreact with IST. These two kinds of immunoreactive cells were distributed quite similarly in the POA. However, by using an immunofluorescence double-labeling method on thinner sections we found that a population of small IST cells in the ventral POA were also immunoreactive to GnRH, but that large IST cells in the dorsal POA were not immunoreactive to GnRH, and small GnRH-ir cells in the most ventral POA were not immunoreactive to the OXT antiserum. In the pituitary gland, GnRH-ir fibers were found in both the neurohypophysis and proximal pars distalis, but IST fibers were found only in the neurohypophysis.

Incidental finding of papillary fibroelastoma on the atrial septum

Papillary fibroelastoma is rare but one of the most common benign primary cardiac tumors after myxoma. This lesion may be associated with embolization, angina and sudden death. The incidental finding of a small pedunculated papillary fibroelastoma arising from the atrial septum detected by transesophageal two-dimensional echocardiography (TEE) in a patient undergoing coronary artery bypass grafting is reported. The advantage of TEE in diagnosing intracardiac tumors is also described.