Golgi vesiculation and lysosome dispersion in cells lacking cytoplasmic dynein

Cytoplasmic dynein, a minus end-directed, microtubule-based motor protein, is thought to drive the movement of membranous organelles and chromosomes. It is a massive complex that consists of multiple polypeptides. Among these polypeptides, the cytoplasmic dynein heavy chain (cDHC) constitutes the major part of this complex. To elucidate the function of cytoplasmic dynein, we have produced mice lacking cDHC by gene targeting. cDHC-/- embryos were indistinguishable from cDHC+/-or cDHC+/+ littermates at the blastocyst stage. However, no cDHC-/- embryos were found at 8.5 d postcoitum. When cDHC-/- blastocysts were cultured in vitro, they showed interesting phenotypes. First, the Golgi complex became highly vesiculated and distributed throughout the cytoplasm. Second, endosomes and lysosomes were not concentrated near the nucleus but were distributed evenly throughout the cytoplasm. Interestingly, the Golgi "fragments" and lysosomes were still found to be attached to microtubules. These results show that cDHC is essential for the formation and positioning of the Golgi complex. Moreover, cDHC is required for cell proliferation and proper distribution of endosomes and lysosomes. However, molecules other than cDHC might mediate attachment of the Golgi complex and endosomes/lysosomes to microtubules.

Expression of the cyclooxygenase-2 gene in gastric epithelium

This study examined the mRNA level of cyclooxygenase-2 (cox-2) in a rat gastric mucosal cell line after growth stimulation in vitro and in rat gastric mucosa before and after acid-induced injury in vivo. RGMI cells were stimulated with fetal calf serum in the in vitro study. Thereafter, the cox-2 mRNA level was examined by Northern analysis. Effects of NS-398, a specific inhibitor of cox-2, and indomethacin on prostaglandin production and cell proliferation were examined in RGM1 cells. In the in vivo study, rats were given 1 ml of 0.6 N hydrochloric acid into the stomach. The level of cox-2 mRNA was examined in rat gastric mucosa after acid administration. Cox-2 mRNA increased 20-60 min after growth stimulation in RGM1 cells. Both NS-398 and indomethacin suppressed prostaglandin production and cell proliferation after growth stimulation. Expression of cox-2 mRNA was observed 40 and 60 min after administration of 0.6 N HCl. Gastric lesions developed within 60 min after HCl administration and healed significantly within 48 h. The present study shows the expression of cox-2 in gastric epithelial cells in vitro and in gastric mucosa after injury in vivo. The results also suggest that cox-2 is involved in de novo synthesis of prostaglandins and cell proliferation in gastric epithelium.

Molecular cloning of a novel gene similar to myeloid antigen CD33 and its specific expression in placenta

We have isolated a novel gene that encodes a protein sharing significant similarity with myeloid antigen CD33. The complete cDNA contains an open reading frame of 1,326 nucleotides encoding 442 amino acids. The deduced amino acid sequence indicates that this molecule belongs to the immunoglobulin (Ig) superfamily and is likely to be a new member of the sialoadhesin sub-family. It is composed of three Ig-like domains; its high degree of similarity to CD33 (70% identity) in the first and second of these domains implies that the placenta-specific gene product is likely to be associated with cell-cell interaction. Northern-blot analysis revealed transcripts of four distinct sizes, 7.5 kb, 5.0 kb, 4.1 kb, and 2.0 kb, specifically in the placenta. Consequently, we termed this gene CD33L (CD33 antigen-like). An alternatively-spliced transcript encoding a 342-amino-acid peptide which lacked the transmembrane region and the cytoplasmic tail was also isolated. We mapped CD33L by fluorescence in situ hybridization (FISH) to human chromosome 19q13.3, where the CD33 gene is also located.

Development of glycosylated human interleukin-1alpha, neoglyco IL-1alpha, by coupling with D-galactose monosaccharide: biological activities in vitro

In the previous study, galactose with C9 spacer was chemically coupled to human recombinant (rh) IL-1alpha in order to study the effect of glycosylation on its activities, and to develop IL-1 with less deleterious effects. In this study we examined a variety of IL-1 activities in vitro, including proliferative effect on T cells, antiproliferative effect on myeloid leukemic cells and melanoma cells, stimulatory effects on IL-6 synthesis by melanoma cells and PGE2 synthesis by fibroblast cells Galactose-introduced IL-1alpha (Gal-IL-1alpha) exhibited reduced activities from 10 to 10000 times compared with unmodified IL-1alpha in all the activities performed in vitro. The competitive binding of 125I-IL-1alpha to mouse T cells and pre-B cells with unlabeled IL-1alpha s suggests a decrease in binding affinities of Gal-IL-1alpha to both type I and type II IL-1 receptors. Therefore, reduced activities of Gal-IL-1alpha are due, at least partially, to the decrease in their receptor binding affinities.

Characterisation of C-type natriuretic peptide receptors in the gill of dogfish Triakis scyllia

Only C-type natriuretic peptide (CNP) has been identified in primitive elasmobranch fish. CNP is the most conserved molecule in the natriuretic peptide family, suggesting that it is the ancestral type. As a first step to investigating the ancestral type of natriuretic peptide receptors, CNP receptors were characterised in an elasmobranch (dogfish, Triakis scyllia) by radioligand-binding analysis using 125I-[Tyr0]-dogfish (df)CNP. None of the modifications of the CNP molecule that occur at the time of iodination (addition of a Tyr residue at the N-terminus, introduction of iodine into Tyr0 or oxidation of Met17) affect the affinity of dfCNP for the receptors. Neither did oxidation of Met17 decrease the ability of CNP to stimulate cGMP production. In the tissues examined, CNP receptors were densest in the gill cells followed by the intestine, interrenal gland and rectal gland, all of which are involved in osmoregulation in elasmobranchs. CNP-stimulated guanylate cyclase (GC) activity was highest in the interrenal gland, intestine, brain and rectal gland, followed by the gill cells. Since the gill cells seem to contain both GC-coupled and uncoupled receptors, this tissue was used to characterise dogfish CNP receptors. Scatchard analysis of the saturation isotherm revealed two classes of binding site: one has a Kd of 24.0 pM and Bmax of 59.9 fmol/mg protein, and the other has low affinity (Kd > 1 nM) and high capacity (Bmax > 200 fmol/mg protein). The higher-affinity binding sites may represent GC-uncoupled receptors, because C-ANF, a specific ligand for GC-uncoupled receptors, almost completely displaced CNP binding. Affinity-labelling experiments showed that dogfish receptors have molecular masses of about 90, 170 and 340 kDa, and CNP binding to the former two receptors is inhibited by C-ANF. After reduction with 2-mercaptoethanol, most 170 kDa labelling was shifted to 90 kDa. It is concluded that GC-uncoupled receptors in the dogfish gill have higher molecular mass than those of mammals and eel (about 65 kDa), and are present mostly as monomers even in non-reducing conditions. However, a small population of GC-coupled receptors is also present, as demonstrated by an increase in cGMP production.

Development of glycosylated human interleukin-1alpha, neoglyco IL-1alpha, by coupling with D-galactose monosaccharide: synthesis and purification

In order to develop glycosylated cytokine, recombinant human IL-1alpha was chemically modified with galactose monosaccharide. Galactose with C9 spacer, 8-(hydrazinocarbonyl)octyl beta-D-galactopyranoside (3), was synthesized by glycosylation of C9 spacer, methyl 9-hydroxynonanoate, with acetobromogalactose, followed by deacetylation and hydrazidation. Total yield of 3 was 43.6% in three steps. Compound 3 was coupled to IL-1alpha by the acyl azide method. The glycosylated IL-1 was purified by anion-exchange chromatography, and galactose coupled to IL-1 was confirmed by R. communis lectin blotting. Based on the molecular weight, the average number of carbohydrate molecules introduced per molecule of IL-1alpha was estimated to be 9.1.

Cloning, sequence analysis, tissue-specific expression, and prohormone isolation of Eel atrial natriuretic peptide

A complementary DNA (cDNA) encoding eel atrial natriuretic peptide (ANP) precursor was specifically amplified from eel atrial mRNAs by rapid-amplification polymerase chain reaction. The sequence analysis of the cDNA using multiple clones revealed that the preproANP consists of 140 amino acid residues carrying a signal sequence at its N-terminus and a mature ANP at its C-terminus. An additional glycine residue was attached to the C-terminus of previously isolated eel ANP. The glycine residue may be used for amidation of the C-terminus or removed after processing. The cleavage site of a signal peptide with 22 amino acid residues was confirmed by isolation of proANP protein from eel atria. The proANP sequence deduced from the cDNA was also confirmed for 71% of the isolated protein. Sequence comparison with other natriuretic peptides revealed that eel ANP is more similar to mammalian ANP than to B-type natriuretic peptide (BNP) at both amino acid and nucleotide sequence levels. The eel ANP gene was a single copy gene as shown by Southern blot analysis. Northern blot analysis showed that eel ANP mRNA is approximately 0.8 kb in size and exclusively detected in the atrium. Thus, eel ANP is a true atrial hormone judging from both the sequence and the site of production. However, reverse transcription-polymerase chain reaction detected ANP message in the brain, gill, cardiac ventricle, red body of swim bladder (rete mirabilis), intestine, head kidney (including interrenal and chromaffin tissues) and kidney. Most of these tissues are involved in ion and/or gas exchange in fishes.

Peripheral nerves regenerated in familial amyloid polyneuropathy after liver transplantation

BACKGROUND

Liver transplantation holds promise as a treatment for familial amyloid polyneuropathy.

OBJECTIVE

To determine whether peripheral nerves regenerate in patients with familial amyloid polyneuropathy after liver transplantation.

DESIGN

Case report.

SETTING

University hospital in Matsumoto, Japan.

PATIENT

A 34 year-old-women with familial amyloid polyneuropathy who had liver transplantation and showed marked clinical improvement 3 years after surgery.

MEASUREMENTS

Histopathologic examination and morphometric analysis of biopsy specimens taken from sural nerves.

RESULTS

Diffuse fiber loss and amyloid deposits were seen in a biopsy specimen of the left sural nerve obtained before liver transplantation (total number of myelinated fibers, 1326/mm2 of the endoneurial area). In the biopsy specimen of the right sural nerve, which was obtained 3 years after transplantation, amyloid deposits remained but the number of myelinated fibers was markedly increased (total number of myelinated fibers, 4740/mm2).

CONCLUSION

Peripheral nerves regenerated in a patient with familial amyloid polyneuropathy after liver transplantation.

Effects of homologous atrial, brain, and C-type natriuretic peptides on isolated heart and blood vessels of bullfrog

The cardiovascular effects of homologous natriuretic peptides (fNPs) were examined in the bullfrog, Rana catesbeiana. Synthetic bullfrog atrial natriuretic (fANP), brain natriuretic (fBNP) and C-type natriuretic peptides (fCNP I and fCNP II), were tested in vitro and compared under the same experimental conditions. All frog NPs produced a significant, and concentration-dependent, reduction in tension (relaxant effect) in the isolated dorsal aorta. Frog CNP II exhibited similar vasorelaxation profile as that of fANP, while fBNP and fCNP I had lower activity than fANP. Frog NPs inhibited norepinephrine induced contraction and fCNP II was most potent. In isolated preparations of atrium and ventricle, fCNP I and II produced a significant, and concentration-dependent, reduction in tension, but neither fANP nor fBNP produced any significant effects. Frog CNP II is most potent among fNPs in relation to reduce the cardiac output. Chronotropic responses of the heart to administrations of NPs were insignificant. The present results for the first time showed that fNPs play roles in the control of cardiovascular system, both blood vessels and heart, in the bullfrog.

Local synthesis of natriuretic peptides in the eel intestine

The intestine is a major osmoregulatory organ in euryhaline fishes which allows them to survive in the sea, and natriuretic peptides have been implicated in regulation of transmural transport. Atrial (ANP) and ventricular natriuretic peptide (VNP) were identified in eel intestine. Elution profiles of ANP and VNP from high-performance liquid chromatography (HPLC) were determined by radioimmunoassay using highly specific antisera. Elution times of immunoreactive ANP and VNP in HPLC were identical to those of authentic peptide standards and were consistent with the relative molecular masses of these peptides. Tissue localization of ANP and VNP was accomplished by fluorescence immunohistochemistry. Immunoreactive cells were observed in the epithelium of anterior, middle, and posterior regions of intestine. Reverse transcription of mRNA isolated from intestine and subsequent polymerase chain reaction amplification yielded appropriate-size products consistent with ANP and VNP expression. Together, these data show that natriuretic peptides are synthesized locally in eel intestine, rather than trapped from the circulation.

A new natriuretic peptide isolated from cardiac atria of trout, Oncorhynchus mykiss

Atrial and brain natriuretic peptides (ANP and BNP, respectively) are two cardiac natriuretic peptides (NPs) found in tetrapods from amphibians to mammals, whereas ANP and ventricular NP (VNP) have been identified in eel hearts. Because VNP has also been found in the rainbow trout ventricle, we attempted to isolate NP from trout cardiac atria in order to determine whether ANP and VNP are common cardiac NPs in teleosts. In the present experiments, we isolated VNP and a novel atrial NP consisting of 29 amino acid residues from the atria. This new trout NP exhibited similar sequence identity to mammalian ANP and BNP (50-60%). Its homology to eel ANP was low (52%) compared with high homology of trout and eel VNP (78%). Based on yield, the content of this new NP in trout atria may be even smaller than that of VNP. The new trout atrial NP exhibited low relaxant activity in the chick rectum (only 1/10 of that of trout VNP), and extremely low vasorelaxant activity in the rat aortic strip (only 1/400 of that of human ANP). However, the new trout NP was equipotent with trout VNP and human ANP in relaxing trout epibranchial artery. Based on the sequence similarity with other NPs and on atrial content, the new NP isolated from trout atria cannot yet be assigned to a known member of the NP family.

Characterisation of natriuretic peptide receptors in eel gill

A radioligand-binding assay was established for eel atrial natriuretic peptide (eANP), and ANP receptors were characterised in the eel gill. ANP binding to the gill membrane fraction was saturable with increasing ligand concentrations and was specific to ANP peptides, i.e. eANP, ventricular natriuretic peptide (VNP) and C-type natriuretic peptide (CNP). A Scatchard analysis revealed a single class of high-affinity receptors with a Kd of 59.2 pM and a Bmax of 67.9 fmol/mg protein. The Kd value is within the range of plasma ANP concentration of the eel. Kd and Bmax did not differ between freshwater (FW)- and seawater (SW)-adapted fish. The gill receptors exhibited similar affinity for eANP, eVNP and eCNP, and ANP binding was almost completely displaced by C-ANF, a specific ligand for guanylate cyclase-uncoupled receptors. The presence of this type of receptor (natriuretic peptide receptor (NPR)-C and NPR-D) was also indicated in eel gill by affinity labelling. cGMP production was stimulated by the addition of eCNP but not by eANP and eVNP, and this was observed only in FW eels. Thus, most ANP receptors in eel gill are NPR-C and NPR-D, but a small number of the NPR-B type are also present in FW eels. In addition to the gill, specific ANP receptors were detected in the red body of the swim bladder, the brain, digestive tracts, kidney, head kidney and urinary bladder, in most of which ANP action has been reported. The density of ANP receptors decreased in most tissues after adaptation to SW except the gill, brain, atrium and spleen.

Interaction of osmotic and volemic mechanisms in secretion of atrial and ventricular natriuretic peptides in eels

In eels, plasma osmolality rather than blood volume is a major regulator of atrial and ventricular natriuretic peptide (ANP and VNP) secretion. The present study examined the effects of changes in blood volume on ANP and VNP secretion stimulated by an increase in plasma osmolality in freshwater-adapted eels. Basal plasma ANP and VNP levels were decreased by 2 ml of blood withdrawal (28% of total blood volume), but not changed by blood volume expansion with 2 ml of 0.9% NaCl solution containing 2% dextran. The blood loss suppressed the increased plasma ANP level caused by an injection of 2.5 ml/kg of 1.7 M NaCl solution at 60 min (120.5 +/- 31.0 fmol/ml, n = 5) compared with controls without blood volume manipulation (586. 6 +/- 43.6 fmol/ml, n = 5), but the plasma ANP level transiently increased in bled fish immediately after osmotic stimulus, probably due to the release of ANP stored in the cardiac tissues after the blood loss. Changes in plasma VNP were not so evident as those of ANP. In contrast, blood volume expansion augmented the increase in plasma ANP and VNP levels within 60 min after osmotic stimulus compared with controls. The recovery of plasma VNP level was quicker than that of plasma ANP. Increases in plasma Na, Cl concentrations, and osmolality were not different among hypovolemic, normovolemic, and hypervolemic eels after osmotic stimulation. It is concluded that volume itself is a minor regulator for ANP and VNP secretion compared with osmotic stimulus, but it plays a modulatory role in osmotically induced ANP and VNP secretion in eels.

Effects of natriuretic peptides and nitroprusside on venous function in trout

Active venous regulation of cardiovascular function is well known in mammals but has not been demonstrated in fish. In the present studies, the natriuretic peptides (NP) rat atrial natriuretic peptide (ANP) and trout ventricular natriuretic peptide (VNP), clearance receptor inhibitor SC-46542, and sodium nitroprusside (SNP) were infused into unanesthetized trout fitted with pressure cannulas in the ventral aorta, dorsal aorta, and ductus Cuvier, and a ventral aorta (VA) flow probe was used to measure cardiac output (CO). In another group, in vivo vascular (venous) capacitance curves were obtained during ANP or SNP infusion. The in vitro effects of NP on vessels and the heart were also examined. ANP, VNP, and SC-46542 decreased central venous pressure (PVen), CO, stroke volume (SV), and gill resistance (RG), whereas systemic resistance (RS) and heart rate (HR) increased. Dorsal aortic pressure (PDA) transiently increased and then fell even though RS remained elevated. ANP decreased mean circulatory filling pressure (MCFP), increased vascular compliance at all blood volumes, and increased unstressed volume in hypovolemic fish. ANP had no direct effect on the heart. ANP responses in vivo were not altered in trout made hypotensive by prior treatment with the angiotensin-converting enzyme inhibitor lisinopril. SNP reduced ventral aortic pressure (PVA), PDA, and RS, increased CO and HR, but did not affect PVen, SV, or RG. SNP slightly decreased MCFP but did not affect compliance or unstressed volume. In vitro, large systemic arteries were more responsive than veins to NP, whereas SNP relaxed both. These results show that, in vivo, NP decrease venous compliance, thereby decreasing venous return, CO, and arterial pressure. Conversely, SNP hypotension is due to decreased RS. This is the first evidence for active regulation of venous capacitance in fish, which probably occurs in small veins or venules. The presence of venous baroreceptors is also suggested.

Role of nitric oxide in oxygen transport in rat liver sinusoids during endotoxemia

To evaluate the role of nitric oxide (NO) in hepatic microcirculation and liver injury during endotoxemia, we studied O2 transport in the hepatic microcirculation of endotoxin-infused rats. Rats were continuously infused with Escherichia coli lipopolysaccharide (LPS) (0.8 mg/kg/h) for 7 hours. LPS increased the plasma levels of NO2- + NO3- and aspartate transaminase (AST), and decreased the bile flow rate and hepatic adenosine triphosphate (ATP) level. Hepatic microcirculation was evaluated by two methods: reflectance spectrophotometry showed a decrease in the oxygenation of hemoglobin (Hb) in the liver, and dual-spot microspectroscopy indicated that LPS administration decreased blood velocity, the oxygenation of Hb, and O2 release from sinusoids to hepatocytes. The observed decreases in the O2 transport parameters were prominent in pericentral sinusoids. All of these phenomena were further aggravated by the administration of N(w)-nitro-L-arginine methyl ester (L-NAME) (5 mg/kg/h) plus LPS, and by aminoguanidine (AMG) (5 mg/kg/h) plus LPS, and these could be reversed by the concomitant administration of L-arginine (L-Arg) (100 mg/kg/h). These results suggest that deterioration of hepatic oxygen transport and liver function induced by endotoxin can be ameliorated by NO.

Primary structure and bioactivity of bullfrog calcitonin

Calcitonin was isolated from the bullfrog, Rana catesbeiana, and the first amino acid sequence of an amphibian calcitonin was determined to be Cys-Ser-Gly-Leu-Ser-Thr-Cys-Ala-Leu-Met-Lys-Leu-Ser-Gln-Asp-Leu-His- Arg-Phe-Asn-Ser-Tyr-Pro-Arg-Thr-Asn-Val-Gly-Ala-Gly-Thr-Pro-NH2. Some portions of this sequence are specific to bullfrog calcitonin, and other portions are similar both to teleost calcitonins and to mammalian calcitonins. Administration of 5 pmol of bullfrog calcitonin to rats revealed a hypocalcemic potency similar to that of salmon calcitonin, at least for the first 3 hr.

A 'kickout' double salto backward tucked dismount from the horizontal bar performed by elite gymnasts

The aim of this study was to identify the differences in the tucked and extended body positions, and in the spatiotemporal characteristics of the motion of the centre of mass, during the performance of kickout and non-kickout double salto backward tucked dismounts. A 16-mm camera, operating at 100 Hz, was used to record double salto backward tucked dismounts during the 1990 national championships in Japan and the USA. A high-scoring kickout group (n = 24) had a significantly (P < 0.005) higher body centre of mass at the tightest tuck position in the first salto, and shorter time to achieve maximum body extension during the second salto, than did a low-scoring non-kickout group (n = 24). Furthermore, the kickout group showed greater height of body centre of mass, larger normalized moment of inertia, and smaller body angle from the vertical at maximum body extension. Consequently, they had longer duration and larger distances of flight than the non-kickout group in which to display the maximum body extension before landing on the mat. It was concluded that the kickout double salto backward tucked dismount is indeed more effective than the non-kickout dismount because it involves (a) greater body extension in an inverted position before passing through the vertical and (b) greater heights of centre of mass at the peak of flight, at the tightest tuck and at maximum body extension. Furthermore, this dismount enhances the display of virtuosity for which bonus points are awarded. The results suggest that this kickout dismount may be helpful in developing the mechanical foundation necessary for learning more advanced dismounts, such as the triple salto backward tucked and double salto backward stretched, with increased effectiveness and safety.

Endothelin-1 in the gastric mucosa in stress ulcers of critically ill patients

OBJECTIVE

Gastric microcirculatory disturbances are involved in the pathogenesis of stress ulcers; however, vasomodulators causing this process are not fully understood. This study was conducted to investigate the role of endothelin 1 (ET-1), a potent vasoconstrictive peptide, in stress ulcers in critically ill patients.

METHODS

Using sandwich enzyme immunoassay, we measured ET-1 content in plasma and the gastric mucosa of 16 critically ill patients with traumatic head injury on admission and of 11 healthy subjects. Gastric mucosal samples were obtained endoscopically. When gastric drainage contained occult blood, endoscopic examination was performed again, and ET-1 concentrations in injured and adjacent normal mucosa were compared.

RESULTS

Plasma and mucosal ET-1 concentrations were significantly higher in critically ill patients on admission (6.1 +/- 0.6 pg/ml and 13.8 +/- 1.6 ng/g, respectively) compared with values in control subjects (2.7 +/- 0.4 pg/ml and 8.2 +/- 0.5 ng/g, respectively) (p < 0.01). The mucosal ET-1 concentration tended to be elevated in patients who had experienced hypoxia compared with those who had not (p = 0.07). In five patients who were again examined endoscopically, the ET-1 concentration in the injured mucosa was significantly higher than that in adjacent mucosa (19.2 +/- 3.2 and 10.1 +/- 1.6 ng/g, respectively; p < 0.05).

CONCLUSIONS

These results suggest that endogenous ET-1 plays an important role in the local pathogenesis of stress ulcers, especially those caused by hypoxia.

Influence of blood substrate levels on myocardial kinetics of iodine-123-BMIPP

To evaluate the influence of blood substrate levels on myocardial uptake of 123I-labeled beta-methyl-iodophenyl-pentadecanoic acid (BMIPP), we examined the correlation between myocardial BMIPP uptake and blood levels of free fatty acid (FFA), glucose, insulin, triglyceride and total cholesterol.

METHODS

In 180 patients, venous blood samples were obtained, and the early and late myocardial uptakes (MU15 and MU150) were determined on planar images at 15 and 150 min after injection at rest, respectively, and the clearance rate of BMIPP from the myocardium was calculated. Dynamic SPECT with BMIPP, PET with [18F]fluoro-deoxyglucose and determination of myocardial carnitine contents were performed in 15, 1 and 3 patients, respectively.

RESULTS

In the 180 patients, MU15 correlated with blood insulin (r = 0.22, p = 0.005) and FFA (r = -0.19, p = 0.02) levels, whereas MU150 did not correlate with blood levels of any variables that were measured (p > 0.05). The clearance rate correlated with blood insulin (r = 0.28, p < 0.001), glucose (r = 0.17, p = 0.03) and FFA (r = -0.40; p < 0.001) levels. The correlations were, however, weak, and five patients (2.8%) with no myocardial BMIPP uptake, all of whom had anterior myocardial infaction, had no characteristics regarding the blood substrate levels. Although dynamic SPECT demonstrated rapid myocardial extraction of BMIPP in 13 patients with myocardial BMIPP uptake, it demonstrated no myocardial BMIPP extraction in two patients with no myocardial BMIPP uptake. One of the five patients with no myocardial BMIPP uptake showed increased myocardial [18F]fluorodeoxyglucose uptake and decreased myocardial carnitine content.

CONCLUSION

The influence of blood substrate levels on myocardial BMIPP uptake is not very significant, although high serum FFA levels may be associated with slow clearance of BMIPP from the myocardium. The complete absence of myocardial BMIPP uptake is not rare and may not be associated with changes in blood substrate levels or early back diffusion of BMIPP.

Delayed development of nervous system in mice homozygous for disrupted microtubule-associated protein 1B (MAP1B) gene

Microtubule-associated protein 1B (MAP1B), one of the microtubule-associated proteins (MAPs), is a major component of the neuronal cytoskeleton. It is expressed at high levels in immature neurons during growth of their axons, which indicates that it plays a crucial role in neuronal morphogenesis and neurite extension. To better define the role of MAP1B in vivo, we have used gene targeting to disrupt the murine MAP1B gene. Heterozygotes of our MAP1B disruption exhibit no overt abnormalities in their development and behavior, while homozygotes showed a slightly decreased brain weight and delayed nervous system development. Our data indicate that while MAP1B is not essential for survival, it is essential for normal time course development of the murine nervous system. These conclusions are very different from those of a previous MAP1B gene-targeting study (Edelmann, W., M. Zervas, P. Costello, L. Roback, I. Fischer, A. Hammarback, N. Cowan, P. Davis, B. Wainer, and R. Kucherlapati. 1996. Proc. Natl. Acad. Sci. USA. 93: 1270-1275). In this previous effort, homozygotes died before reaching 8-d embryos, while heterozygotes showed severely abnormal phenotypes in their nervous systems. Because the gene targeting event in these mice produced a gene encoding a 571-amino acid truncated product of MAP1B, it seems likely that the phenotypes seen arise from the truncated MAP1B product acting in a dominant-negative fashion, rather than a loss of MAP1B function.

Circular trajectory formation during blind locomotion: a test for path integration and motor memory

Eight healthy subjects were asked to walk blindfolded along circular paths of different radii after several practice trials with vision. Their task was to stop after completing two full revolutions. They always walked counter-clockwise (CCW) in (a) a control condition (CONTROL), including the instructions mentioned above, (b) with the further instruction to count backwards in twos (MENTAL), (c) with the instruction to count loudly (LOUD). The movement of two markers lying along the head naso-occipital axis was recorded by means of an ELITE system. Total walked distance (DISTANCE), total head turning angle (ANGLE) and average radius (RADIUS) of the trajectories performed were measured. All subjects were able to perform approximately circular trajectories. They consistently overshot the ideal radius independently of the condition and circle size, undershot the total angle and overshot total distance. The LOUD condition induced greater errors in the performance but only on total distance (P<0.05). A strong correlation was found between the errors in radius and total distance but not between distance and total angle. Principal components analysis suggested that radius and distance share a common source of errors while total angle produced independent errors. The results indicate that (a) circular trajectories can be generated starting from spatial and/or motor memory, without the aid of visual information; (b) the task needs some attentional control and does not involve simple automatic processing of afferent information; (c) different sensory information or different processing modes are probably involved in the estimation of the curvature and length of the walked path on the one hand, and of the total rotation angle on the other.

Imidazolone, a novel advanced glycation end product, is present at high levels in kidneys of rats with streptozotocin-induced diabetes

We produced a monoclonal antibody to imidazolones A and B, novel advanced glycation end products formed from the reaction of 3-deoxyglucosone (3-DG) with the guanidino group of arginine. Liquid chromatography/mass spectrometry demonstrated that the formation of imidazolone A by incubating 3-DG with arginine is very rapid, reaching a maximum concentration within 24 h, but the formation of imidazolone B is very slow and low in quantity even after 2 weeks. Thus, at physiological conditions the formation of imidazolone A is dominant, while that of imidazolone B is negligible. Immunochemistry demonstrated that the imidazolone content in the kidneys of streptozotocin-induced diabetic rats was significantly higher than in the control rats. Serum levels of 3-DG in the diabetic rats were also significantly higher than in control rats. 3-DG attacks the arginine residues of the tissue proteins, producing imidazolone at high levels in the kidneys affected by diabetic nephropathy.

Immunohistochemical detection of imidazolone, a novel advanced glycation end product, in kidneys and aortas of diabetic patients

To investigate the role of the Maillard reaction in the pathogenesis of diabetic complications, we produced several clones of monoclonal antibodies against advanced glycation end products (AGEs) by immunizing mice with AGE-modified keyhole limpet hemocyanin, and found that one clone (AG-1) of the anti-AGE antibodies reacted specifically with imidazolones A and B, novel AGEs. Thus, the imidazolones, which are the reaction products of the guanidino group of arginine with 3-deoxyglucosone (3-DG), a reactive intermediate of the Maillard reaction, were found to be common epitopes of AGE-modified proteins produced in vitro. We determined the erythrocyte levels of imidazolone in diabetic patients using ELISA with the monoclonal anti-imidazolone antibody. The imidazolone levels in the erythrocytes of diabetic patients were found to be significantly increased as compared with those of healthy subjects. Then we studied the localization of imidazolone in the kidneys and aortas obtained from diabetic patients by immunohistochemistry using the antibody. Specific imidazolone immunoreactivity was detected in nodular lesions and expanded mesangial matrix of glomeruli, and renal arteries in an advanced stage of diabetic nephropathy, as well as in atherosclerotic lesions of aortas. This study first demonstrates the localization of imidazolone in the characteristic lesions of diabetic nephropathy and atherosclerosis. These results, taken together with a recent demonstration of increased serum 3-DG levels in diabetes, strongly suggest that imidazolone produced by 3-DG may contribute to the progression of long-term diabetic complications such as nephropathy and atherosclerosis.

Mitogenic activity toward human breast cancer cell line MCF-7 of two bFGFs purified from sera of breast cancer patients: co-operative role of cathepsin D

Mitogenic activity toward MCF-7 cells of two immunoreactive (high-molecular-weight form bFGF, HMW-bFGF; and 16-K bFGF, having the same molecular weight as recombinant bFGF) purified from pooled sera of breast cancer patients by heparin-affinity chromatography and gel filtration was investigated. The mitogenic activity of 16-K bFGF toward the cells was equal to that of recombinant bFGF, whereas the mitogenic effect of HMW-bFGF was weak. Most of the mitogenic activity of these two bFGFs was neutralized by anti-bFGF antibody. Also, the mitogenic activity of both HMW-bFGF and 16-K bFGF was markedly enhanced by aspartyl protease (cathepsin D), which is secreted in excess by breast cancer cells and is responsible for the enzymatic degradation of the extracellular matrix (ECM). By an enzyme immunoassay, we detected cathepsin D-mediated release of recombinant bFGF previously bound to the ECM of MCF-7 cells into the conditioned medium, and also observed cathepsin D-mediated proteolysis of HMW-bFGF to release free 16-K bFGF. These results suggest that 16-K bFGF is the bFGF molecule itself in the blood and that HMW-bFGF is a circulating form of bFGF in blood whose mitogenic activity is regulated by cathepsin D.

Sequence analysis of a 685-kb genomic region on chromosome 3p22-p21.3 that is homozygously deleted in a lung carcinoma cell line

Frequent chromosomal aberrations and/or losses of heterozygosity involving the short arm of chromosome 3 in carcinomas of the lung, kidney and other tissues imply that multiple putative tumor suppressor genes may be present on this chromosomal arm. To search for one of these genes, we determined DNA sequences in the genomic region at 3p22-21.3 where we had previously detected a homozygous deletion in a lung cancer cell line. The DNA sequence results of an about 685-kb region indicated that the size of the homozygously deleted segment was 638,489 bp, in which we identified only four genes including the integrin alpha RLC and the trans-Golgi p230 genes, both reported previously. The predicted amino acid sequences of one of the two novel genes showed high homology to villin, a human cytoskeleton protein; those of the other gene, termed HYA22, revealed significant homology to YA22, a hypothetical protein predicted from DNA sequences of Schizosaccharomyces pombe. The computer programs HEXON or GRAIL were able to predict three-fourths of the exons; the smallest exon predicted by either program was 46 base pairs. Repetitive sequences contained in the genomic region included 151 copies of the Alu sequence (1 copy/every 4.5 kb), 19 copies of the L1 sequence (1 copy/every 36 kb), and 10 copies of the THE sequence.