The T-cell antigen CD5 acts as a receptor and substrate for the protein-tyrosine kinase p56lck

CD5 is a T-cell-specific antigen which binds to the B-cell antigen CD72 and acts as a coreceptor in the stimulation of T-cell growth. CD5 associates with the T-cell receptor zeta chain (TcR zeta)/CD3 complex and is rapidly phosphosphorylated on tyrosine residues as a result of TcR zeta/CD3 ligation. However, despite this, the mechanism by which CD5 generates intracellular signals is unclear. In this study, we demonstrate that CD5 is coupled to the protein-tyrosine kinase p56lck and can act as a substrate for p56lck. Coexpression of CD5 with p56lck in the baculovirus expression system resulted in the phosphorylation of CD5 on tyrosine residues. Further, anti-CD5 and anti-p56lck coprecipitated each other in a variety of detergents, including Nonidet P-40 and Triton X-100. Anti-CD5 also precipitated the kinase from various T cells irrespective of the expression of TcR zeta/CD3 or CD4. No binding between p59fyn(T) and CD5 was detected in T cells. The binding of p56lck to CD5 induced a 10- to 15-fold increase in p56lck catalytic activity, as measured by in vitro kinase analysis. In vivo labelling with 32P(i) also showed a four- to fivefold increase in Y-394 occupancy in p56lck when associated with CD5. The use of glutathione S-transferase-Lck fusion proteins in precipitation analysis showed that the SH2 domain of p56lck could recognize CD5 as expressed in the baculovirus expression system. CD5 interaction with p56lck represents a novel variant of a receptor-kinase complex in which receptor can also serve as substrate. The CD5-p56lck interaction is likely to play roles in T-cell signalling and T-B collaboration.

[A case of intracranial arteriovenous malformation presenting with intracranial hypertension]

A case of unruptured arteriovenous malformations (AVMs) presenting benign intracranial hypertension is reported. A 14-year-old male suffered from headache and papilledema. Intracranial pressure was 260 mmH2O. Unenhanced CT demonstrated no evidence of hemorrhage or hydrocephalus. Angiogram demonstrated a large AVM in the left temporal lobe supplied by the left posterior cerebral artery and left middle cerebral artery. It drained into the transverse sinus. Surgical excision of the AVM eliminated the headache and papilledema. AVM causes hemorrhage in 50% of cases, seizure in 30%, and other focal neurological deficits in 20%. Benign intracranial hypertension is an uncommon effect of unruptured AVMs. Only 13 cases have been reported in the literature. Benign intracranial hypertension associated with unruptured AVMs occurs in young patients with high flow AVMs that drain into the major sinus. The mechanism of intracranial hypertension associated with unruptured AVM is unknown. However, there are several possible mechanisms of intracranial hypertension associated with unruptured AVMs. The arterial blood shunting into a major sinus impedes venous return from the surrounding brain. That causes the increase of cerebral blood volume and the elevation of sinus pressure. This mechanism would reduce CSF absorption and would increase intracranial pressure. Pharmacological therapy is ineffective in controlling intracranial hypertension. Surgical excision of AVM effectively reduced intracranial hypertension. Thus, surgical excision of AVMs, if it can be done with low risk, is the treatment of choice to decrease intracranial hypertension in patients with unruptured cerebral AVMs.

Magnesium regulates ion transport across canine tracheal epithelium

We examined the effect of Mg2+ on potential difference (PD) and short circuit current (SCC) of the posterior epithelial membrane of canine trachea using an Ussing chamber. After the exchange to a Mg(2+)-free solution, PD and SCC rapidly increased, reaching maximal values within 3 min, followed by a gradual return towards the baseline over 60 min. In a Ca(2+)-free solution, Mg2+ removal did not alter PD and SCC values. Increased Mg2+ in the solution produced significant gradual decreases in PD and SCC. The decreases in PD and SCC were reversed by the addition of excessive Ca2+ to the solution. Mg2+ removal did not alter significantly isoproterenol-induced increases in PD and SCC values, while increased Mg2+ significantly reduced the increases. These findings indicate that extracellular Mg2+ is an important determinant in ion transport across the airway epithelium, probably through antagonistic actions of Mg2+ and Ca2+.

Respiratory load compensation during hypercapnic ventilatory response in pulmonary emphysema

The purpose of this study is to examine the relationship between mechanical factors and the load compensation during hypercapnia in emphysema. In 36 clinically stable patients, we conducted pulmonary function tests and hypercapnic ventilatory response (HCVR) tests with and without inspiratory flow-resistive loading (IRL) (17 cm H2O/L/s). The mean value of HCVR significantly decreased with IRL, while that of the mouth occlusion pressure (P0.1) response increased. Regardless of IRL, the HCVR values were correlated with FEV1/FVC and airway resistance. The load compensation, evaluated by the ratio of the HCVR value and the P0.1 response before and after IRL, was inversely correlated with percent FRC (r = -0.38, r = -0.39; both p < 0.05). Breathing pattern analysis at the end-tidal pressure of carbon dioxide of 55 mm Hg elicited the decrease of (tidal volume/inspiratory time (VT/TI) and the increase of TI and TI/TTOT. Although the absolute changes of VT and f were inconsistent among subjects, each relative ratio before and after IRL was correlated again with percent FRC (r = -0.46, r = 0.44: both p < 0.01). Therefore, the position of the inspiratory muscles at the onset of inspiration may influence the load compensation during hypercapnia in emphysema.

Development and characterization of macrophage hybridomas derived from murine peritoneal exudate cells

Mouse macrophage (Mphi) hybridoma clones were generated by somatic cell hybridization of myeloma X63 cells (H-2d) with C57BL/6 (H-2b) peritoneal exudate cells elicited with a streptococcal preparation, OK432, or thioglycollate medium. Although they hardly adhered to plastic dishes and could not be morphologically distinguished from parental X63 tumor cells, the clones retained Mphi characteristics. These included phagocytosis and production of lysozyme and nonspecific esterase, suggesting that they were hybridomas derived from Mphi. Some of them expressed various levels of Ia antigen and Fc receptor. Because they induced proliferation of T cells from Balb/c mice but not those from C57BL/6 mice, the Ia antigen of Mphi hybridoma was assumed to be derived from peritoneal Mphi. The level of proliferation induction was correlated to the level of Ia antigen expression. Several clones produced a factor that cytostatically inhibited growth of murine mammary carcinoma and was serologically identified with arginine deiminase.

Growth regulation in primary culture of rabbit arterial smooth muscle cells by platelet-derived growth factor, insulin-like growth factor-I, and epidermal growth factor

Many studies have linked the proliferation of smooth muscle cells (SMC) to the development of atherosclerotic lesions. We examined the effects of platelet-derived growth factor (PDGF), insulin-like growth factor-I (IGF-I), and epidermal growth factor (EGF) on the regulation of SMC grown on type I collagen-coated dishes in serum-free primary culture. When added alone, PDGF (10 ng/ml), IGF-I (20 ng/ml), and EGF (10 ng/ml) produced minimal effects on BrdU (5-bromo-2'-deoxyuridine) incorporation into cellular DNA and on cell growth. However, simultaneous addition of PDGF and IGF-I significantly stimulated DNA synthesis and cell growth. The combination of PDGF, IGF-I, and EGF synergistically stimulated DNA synthesis and cell proliferation. Flow cytometric analysis indicated that type I collagen alone promoted the phenotypic modulation and progression of the cells from the G0 (contractile phenotype) to the G1A phase (intermediate phenotype), PDGF and IGF-I, together, stimulated the rate of cell transition from the G1A to the G1B and S phases (synthetic phenotype), and PDGF, IGF-I, and EGF together stimulated the rate of cell transition into the S and G2+ M phases. In contrast, in quiescent secondary cultured SMC (G1B phase), PDGF alone was able to initiate DNA synthesis, although IGF-I and EGF were required to complete DNA synthesis. These results reveal that PDGF and IGF-I stimulate the cells to complete the G1A phase and proceed to the G1B phase and that EGF regulates the rate of entry into the S phase in rabbit SMC in primary culture. Furthermore, differences in the responsiveness to these growth factors between primary and secondary cultures reflected the varying phenotypic properties of vascular SMC.

Differential effects of chronic L-dopa treatment on lipid peroxidation in the mouse brain with or without pretreatment with 6-hydroxydopamine

Whether or not chronic L-dopa treatment (100 mg/kg, intraperitoneally (i.p.), twice daily for 4 weeks) alters lipid peroxidation in the brain as an indicator of neuronal damage was examined in normal mice and mice in which catecholamine (CA) neurons had been injured previously by the administration of 6-hydroxydopamine (6-OHDA), followed by recovery. In normal mice, chronic L-dopa treatment reduced the thiobarbituric acid reacting substances (TBARS) level, an indicator of lipid peroxidation, in the cerebral cortex. In contrast, in mice with CA neuronal injury induced by pretreatment with 6-OHDA, the chronic L-dopa treatment markedly increased the TBARS in the striatum and frontal cortex, despite recovery of the striatal dopamine levels similar to those in the control mice. These findings suggest that the long-term high-dose administration of L-dopa enhances the progression of neuronal damage in patients with injured CA neurons such as those with Parkinson's disease.

Structure and regulation of the chicken erythroid delta-aminolevulinate synthase gene

Erythroid cells regulate heme biosynthesis in a manner that is distinct from all other cell types. While heme negatively regulates the synthesis of the housekeeping delta-aminolevulinate synthase (ALAS-N) in all non-erythroid cells, the expression of an erythroid-specific isozyme (ALAS-E) is developmentally regulated in red blood cells. As a first step towards understanding the molecular basis for the transcriptional regulation of ALAS-E during erythropoiesis, we cloned and characterized the chicken ALAS-E locus. This gene spans 18 kbp and is composed of eleven exons. The intron/exon structure of erythroid ALAS was found to be conserved among several vertebrate species. Direct RNA sequencing identified a 5' untranslated region that is derived from two continuous exons and is predicted to form a very stable stem-loop structure that bears resemblance to the ferritin iron-responsive element. Tissue-specific expression of the ALAS-E gene was analyzed by transient transfection assays in hematopoietic cells of both erythroid and non-erythroid origins. These experiments identified distal (-784 to -505 bp) and proximal (-155 to +21 bp) promoter elements which are required for high level, erythroid-specific transcription.

[Angiomyolipoma of the anterior mediastinum--a case report]

An asymptomatic 22-year-old female showed an enlarged mediastinal shadow in a chest X-ray mass screening. Computed tomogram indicated a tumor with a CT-number of 7-8 in her left anterior mediastinum, adjacent to the pericardium. With MRI the tumor showed a low signal intensity of T1 weighted images and a high signal intensity of T2 weighted images. Thoracotomy revealed that the tumor was yellow-whitish, and had a size of 7 x 7 x 1 cm. It was histologically composed of fatty tissue, smooth muscle, and vascular tissue, and was diagnosed as angiomyolipoma. Although angiomyolipomas are often found in the kidney, they are very rare in the mediastinum and difficult to diagnose by image analysis.

Temporal and spatial changes in GATA transcription factor expression are coincident with development of the chicken optic tectum

The molecular mechanisms specifying patterns of gene expression in the vertebrate brain, which in turn determine the developmental fates of specific neurons, are yet to be clearly defined. Individual members of a recently identified family of transcriptional regulatory proteins, the GATA factors, are required for the differentiation of certain hematopoietic cell lineages. We show here that two of the members of this gene family, GATA-2 and GATA-3, are expressed within discrete cell populations of the chicken optic tectum during embryogenesis, and that they have highly restricted patterns of expression in the developing chicken brain. Furthermore, the induction of GATA factor expression within specific cell layers parallels the well established spatial (rostral to caudal) and temporal pattern of optic tectum development. The observation that both the timing of appearance and the localization of expression of GATA-2 and GATA-3 are correlated with optic tectum development suggest that these transcription factors may be associated with the initiation of gene transcription required for the determination of specific neuronal fates within visual areas of the vertebrate brain.

Effect of maternal paraquat administration on the fetal ductus arteriosus in the rat

The ductus arteriosus (DA) in the fetal rat was calibrated using a whole-body freezing method, 3 hr after maternal treatment with paraquat at a dose of 25 mg/kg of body weight on days 19-21 of gestation. On days 20 and 21, the DA was significantly constricted. The DA was also significantly constricted on day 19 2/3 but not on day 19 1/2. It is concluded that paraquat has a constrictive effect on the DA and that the onset of this effect occurs in the first half of day 19 of gestation.

[Genetic characteristics of Japanese pedigrees with Leber's hereditary optic neuropathy]

Although point mutation at nucleotide position 11778 of mitochondrial (mt) DNA is associated with Leber's hereditary optic neuropathy (LHON), the existence of the mutation alone is not sufficient for LHON expression. Whether the mutation is homo- or heteroplasmic, or whether secondary mutations additionally exist did not explain intra- or interfamilial phenotypic variations in at least 10 Japanese pedigrees tested. Segregation analysis showed that both mtDNA mutation and abnormal X-linked gene (XLG) are necessary for development of optic atrophy, and that an unfortunate X-inactivation is involved. The frequency of the presumed abnormal XLG and its penetrance are estimated to be about 0.1 and 0.2, respectively. The latter value is about twice as high as the value for Caucasian pedigrees. This evidence suggests a relatively homogeneous mtDNA abnormality and a low disease threshold derived from the XLG abnormality in female offsprings in Japanese LHON maternal lines.

Amplification of N-myc gene and increase of urinary VMA and HVA in patients with neuroblastic tumors

Neuroblastic tumor cases in our departments were evaluated in terms of the stage of the tumor, N-myc amplification, urinary vanillylamndelic acid (VMA)/homovanillic acid (HVA) and survival rate. Two asymptomatic cases, diagnosed when under a year old by mass screening, had no amplifications of N-myc but showed more than one value of urinary VMA/HVA ratio. The patients are now doing well eight years after complete excision of the neuroblastoma which had originated in the sympathetic ganglion. On the other hand, two other symptomatic cases, operated on at the ages of 3 and 5 years, showed remarkable amplifications with less than one value of urinary VMA/HVA, and died from the tumor soon after partial resection of the neuroblastoma and ganglioneuroblastoma which had originated in the adrenal gland and the sympathetic ganglion, respectively. The present monograph reports our cases and discusses prognostic factors.

Antiphospholipid antibodies. A prognostic factor in sarcoidosis?

Serum antibodies against five types of phospholipids, antiphospholipid antibodies (aPL), were determined by an enzyme-linked immunosorbent assay in 55 patients with sarcoidosis. Either IgG or IgM aPL were detected in 21 patients (38 percent). This positive rate was significantly higher than that (7 percent) of healthy control subjects (p < 0.001). In terms of immunoglobulin classes, 5 cases had IgG aPL only, 11 cases had IgM aPL only, and 5 cases had both classes of aPL. No correlation was observed between the occurrence of aPL and disease activity of sarcoidosis. A significant correlation was noted between the occurrence of aPL and many extrathoracic organ lesions or the persistence of abnormal chest x-ray film findings for periods of 2 and 5 years. Taken together, the presence of aPL in sarcoidosis is a useful index to judge the prolongation of the disease.

[Mitochondrial encephalomyopathy associated with parkinsonism and a point mutation in the mitochondrial tRNA(Leu)(UUR)) gene]

We report a patient with mitochondrial encephalomyopathy presenting parkinsonism, as well as her brother who had ataxia but not parkinsonism. Both patients had myopathy, deafness, and insulin-dependent diabetes mellitus. The proband was a 55-year-old woman, who has developed progressive difficulty in walking and slowness of movement since 53 years of age, becoming bed-ridden at 55. Neurological examination revealed mental impairment, a masked face, Myerson's sign, vertical supranuclear ophthalmoplegia, and severe sensorineural deafness, hypokinesia, rigidospasticity, and weakness of the extremities. But tremor and cerebellar ataxia were absent. Her 48-year-old brother gradually developed weakness of the lower extremities and drunken gait over a few years. On neurologic examination, vertical supranuclear ophthalmoplegia, moderate sensorineural deafness, and cerebellar ataxia were present, but parkinsonism was absent. Three other siblings were reported to have died in early childhood. Cranial MR imaging showed cerebral atrophy and mild atrophy of the cerebellar vermis as well as mild periventricular hyperintensities in T2-weighted images in both patients. However, no infarcts were seen. Laboratory investigations revealed slightly elevated lactate and pyruvate levels in the proband and elevation of pyruvate in her brother. A biopsy specimen obtained from the quadriceps muscle showed ragged-red fibers with modified Gomori trichrome staining, and a decrease of complex I+III and complex II+III activity in the proband. Mitochondrial DNA (mtDNA) analysis using the polymerase chain reaction and restriction enzyme Apa I showed a point mutation in the tRNA(Leu)(UUR)) gene (an A to G transition at nucleotide 3243) in both patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Simultaneous determination of the optical constants and thickness of very thin films by using soft-x-ray reflectance measurements

A nonlinear, least-squares curve-fitting method is described that simultaneously determines the optical constants and the thickness of a very thin (≲ 100-Å) film from reflectance versus angle of incidence (R - θ) data measured in the soft-x-ray region. The method is applied to R - θ data obtained for very thin, sputtered films of carbon (65 Å thick) and gold (94 Å thick) at photon energies of 60-900 eV. The results show that the present method is capable of accurately determining the thickness of very thin films even for transparent materials, and that the obtained optical constants are in good agreement with values reported for films with a thickness of 1000 Å.

Cloning of the pka1 gene encoding the catalytic subunit of the cAMP-dependent protein kinase in Schizosaccharomyces pombe

We have isolated Schizosaccharomyces pombe genes that confer sterility to the fission yeast cell when expressed from a multicopy plasmid. One of these genes strongly hybridized to a probe carrying the open reading frame of Saccharomyces cerevisiae TPK1, which encodes a catalytic subunit of the cAMP-dependent protein kinase (protein kinase A). This S. pombe gene, named pka1, has a coding potential of 512 amino acids, and the deduced gene product is 60% identical with the S. cerevisiae Tpk1 protein in the C-terminal 320 amino acids. Disruption of pka1 slows cell growth but is not lethal. The resultant cells, however, are highly derepressed for sexual development, readily undergoing conjugation and sporulation in the absence of nitrogen starvation. They are, thus, phenotypically indistinguishable from the adenylyl cyclase-defective (cyr1-) cells previously characterized, except that the pka1- spores are retarded in germination, whereas the cyr1- spores are not. Disruption of pka1 is epistatic to a defect in cgs1, which encodes the regulatory subunit of protein kinase A. These results strongly suggest that the product of pka1 is a catalytic subunit of protein kinase A and, furthermore, that S. pombe has only one gene encoding it. This situation contrasts with the case of S. cerevisiae, in which three genes encode the catalytic subunits.

Endoneurosurgical treatment for hydrocephalus caused by intraventricular tumors

A flexible therapeutic ventriculoscope allowing for the use of a variety of different instruments has been developed. Endoneurosurgical instruments are composed of an endoscopic contact YAG laser endoprobe, grasping forceps and a punctured needle. Endoneurosurgical procedures include biopsies, III ventriculostomy, fenestration of the septum pellucidum, aspirations of cysts and excisions of tumors in the cerebrospinal fluid pathways. Our ventriculoscope allows the initial treatment for progressive hydrocephalus caused by intraventricular tumors to take the form of reducing ventricular size and decreasing intracranial pressure, and it can also be used to perform biopsy examinations, so that acceptable neurological outcomes and an accurate histological diagnosis can be obtained with fewer side effects. The subsequent therapies for hydrocephalus caused by intraventricular tumors include radical surgery for benign tumors, irradiation for radiosensitive tumors, and irradiation and/or chemotherapy for either malignant or disseminated tumors. We have tried to avoid the sequelae of shunt surgery and have achieved maximum effects with the minimum of procedures by using our ventriculoscope.

Regulation of transcription by dimerization of erythroid factor NF-E2 p45 with small Maf proteins

Transcription factor NF-E2 is crucial for regulating erythroid-specific gene expression. Cloning of the NF-E2 p45 protein has revealed that it contains a basic region-leucine zipper (b-zip) domain which associates with another unidentified protein (of relative molecular mass 18,000) to form functional NF-E2. We show here that products of the maf proto-oncogene family, MafF, MafG and MafK (the small Maf proteins) which possess a b-zip DNA-binding domain but lack a canonical transactivation domain, directly control the DNA-binding properties of p45 by heterodimeric association with p45. Whereas homodimers of the small Maf proteins act as negative regulators, heterodimers composed of Maf and p45 support active transcription in vivo. These results indicate that one (or all) of the small Maf proteins is the second constituent chain required for NF-E2 activity, and that negative as well as positive regulation can be achieved through an NF-E2 site, depending on the equilibrium concentrations of p45 and the Maf proteins inside erythroid cells.

Polyhedral assembly of a membrane protein in its three-dimensional crystal

A novel ordered assemblage of bacteriorhodopsin, a transmembrane protein functioning as a light-driven proton pump, is found in its three-dimensional crystal. Atomic force microscope images of the crystal surface reveal that spherical protein clusters with a diameter of approximately 50 nm are hexagonally close-packed. Electron micrographs of mechanically disintegrated crystals show that the inside of the protein cluster is filled with the mother liquor. The crystal is made up of hollow protein clusters. When disintegrated crystals are illuminated in the presence of a lipophilic anion, a significant alkalization of the external medium occurs. This result indicates that the protein cluster contains native lipids and that the cytoplasmic side of the protein faces the external medium. X-ray diffraction patterns and the observed diameter of the spherical shell suggest that approximately 200 bacteriorhodopsin trimers are aligned on a polyhedral surface lattice. Another remarkable feature of the spherical assemblies of bacteriorhodopsin is that they fuse with each other at low ionic strength and occasionally form a tubular or doughnut-like structure. The concept of membrane protein polymorphism is introduced on the basis of these observations, and it is used to describe the dynamic structure of some other biological membranes.

Pharmacological and model-based interpretation of neuronal dynamics transitions during sleep-waking cycle

Power spectral analysis has been applied to spontaneous single neuronal activities during the sleep-waking cycle in various regions of the cat's central nervous system. During slow-wave sleep (SWS), the spontaneous activities of many neurons had a white noise-like power-spectral density profile in a very low frequency range (0.01-1.0 Hz) whereas, during rapid-eye-movement sleep (REMS), they showed a 1/f-like spectral pattern. This spectral transition between SWS and REMS was hypothesized to depend on the influence of serotonergic and cholinergic neuronal activity which is considered to modulate various brain functions. According to both pharmacological experiments and simulation studies with a neural network model, it was concluded that the serotonergic system may have a function to eliminate slow fluctuations in neuronal activity in wide areas, from the reticulo-thalamo-neocortical to the limbic systems. Consequently, simple signal processing of spontaneous neuronal activity has elucidated an important neurophysiological fact, which may lead to a principle of the basic brain function and its mechanism.

Role of prostate-specific antigen and digital rectal examination in the detection of prostate cancer

Prostate-specific antigen (PSA) is a kallikrein-like serine protease that is secreted exclusively by the epithelial cells of all types of prostatic tissue, benign and malignant. Its serum concentration is raised in men with prostatic disease including cancer. We have evaluated its usefulness in the diagnosis of prostate cancer by measuring serum PSA concentrations in 260 men aged 50 years or over. All had abnormalities at digital rectal examination (DRE) involving suspected cancer, signs and symptoms of benign prostatic hyperplasia and equivocal findings on DRE, and miscellaneous other conditions, including hematospermia, chronic prostatitis and microscopic hematuria. Transrectal prostatic needle biopsies were performed in the men with abnormal findings on DRE or elevated serum PSA (above 4 ng/ml). Serum PSA ranged from 4.0 to 9.9 ng/ml in 14 (5%) of the 260 men. Four of the men in this group (31%) who underwent prostatic biopsy had prostate cancer. Serum PSA levels greater than or equal to 10.0 ng/ml were found in 8 (3%) of the 260 men. 5 of these 8 (63%) who underwent prostatic biopsy had cancer. If DRE alone had been used to screen the men having biopsies, 4 of the 10 cancers (40%) would have been missed. If PSA alone had been used to screen these men, only 1 of the 10 cancers would have been missed. Serum PSA measurement was more reliable than DRE for detecting prostate cancer. Since these two methods do not always detect the same malignant tumor, the combined use of DRE and PSA testing affords a more complete evaluation of the prostate gland for malignant involvement.