(6R)-Tetrahydrobiopterin Increases the Activity of Tryptophan Hydroxylase in Rat Raphe Slices

The effects of (6R)- and (6S)-tetrahydrobiopterin (BPH4), tetrahydroneopterin, and 6-methyltetrahydropterin on the activity of tryptophan hydroxylase were investigated in rat raphe slices. The activity of tryptophan hydroxylase was estimated by measurement of 5-hydroxytryptophan (5-HTP) formation under inhibition of aromatic L-amino acid decarboxylase with use of HPLC-fluorometric detection. (6R)-BPH4 (the naturally occurring form) at 42 microM, tetrahydroneopterin at 50 microM, and 6-methyltetrahydropterin at 100 microM increased tryptophan hydroxylase activity to 350, 145, and 146% of control values, respectively. (6S)-BPH4, however, had no significant effects on tryptophan hydroxylase activity. These results suggest that tryptophan hydroxylase is subsaturating in vivo for the naturally occurring cofactor, (6R)-BPH4, and that the concentration of (6R)-BPH4 may play an important role for the regulation of tryptophan hydroxylase activity in vivo.     

Immunohistochemical studies of the serotonergic supraependymal plexus in the mammalian ventricular system, with special reference to the characteristic reticular ramification

Distributional and morphological features, especially characteristics of the ramification of serotonin-containing supraependymal fibers (SEF), were studied in the ventricular systems of mammals (mouse, rat, guinea pig, rabbit, cat, dog, monkey) by means of a modified peroxidase antiperoxidase technique, using antiserotonin antiserum prepared in our laboratory. SEF were present in all ventricular systems, except on the third ventricle floor and in the choroid plexus. The density of SEF was higher in the smaller species. In the rat, light- and scanning electron microscopical SEF were almost completely abolished 1 week after intraventricular administration of 5,6-dihydroxytryptamine. Ramification of SEF was complicated; the SEF formed a true network with frequent anastomosing. In the ventricular system of rats rendered hydrocephalic by kaolin administration, the mode of axonal branching in the supraependymal plexus could best be analyzed by the scanning electron microscope because the meshes of the plexus were spread out.     

Role of endogenous complement in monoclonal IgM antibody-dependent leukemia suppression in vivo: participation of C3b

The mechanism by which McAb of the IgM isotype causes prolonged survival of leukemic rats was investigated. The participation of endogenous C in the suppression of IgM-sensitized leukemia cells was demonstrated by the observations that a) suppression was abrogated in CVF-treated rats, and b) the CVF effect was partially reversed if C3b was provided on the surface of IgM-sensitized leukemia cells.     

Fetus-in-fetu: report of a case

A 5 month-old female was brought to our clinic because of diarrhea and abdominal distension. A plain radiograph demonstrated a mass with a vertebral column in the right upper quadrant of the abdomen. At operation a mass was found to be retroperitoneal, well encapsulated, and connected to the abdominal aorta of the host by two small vessels; no other connections and adhesions were seen between the mass and the host. The ovaries, uterus, and other pelvic and abdominal viscera of the host were normal. The mass was diagnosed as a fetus-in-fetu. The fetus-in-fetu, encapsulated with an amniotic capsule, was covered with skin and had a top with long hair, two protuberances, an amniotic hernial sac, upper limbs with syndactylic fingers, a gluteal region, and lower limbs with polysyndactylic toes. A brain mass and a spinal cord were identified in the cranial cavity and the vertebral canal. Several spinal ganglia and a nerve plexus were found. A noselike structure, upper lip, maxillalike bone with teeth, tonguelike structure, intestines, ribs, bones of the extremities, and skeletal muscles were also identified. A cloacalike cyst was observed to have an opening in the external female genitalia. Microscopically, a small number of motor neurons were seen in the brain mass and the anterior horn of the spinal cord. In the spinal ganglia, ganglion cells were differentiated. The submucosal and myenteric plexuses were seen in the intestinal wall. Well-differentiated muscle fibers were often accompanied with myelinated nerve fibers. Hematopoiesis was observed in the cranial bone marrow. The presence of the sex chromatin was confirmed in the nuclei of motor neurons and polymorphonuclear leukocytes. Thus, the present fetus-in-fetu, which was connected to the abdominal aorta of the host by two vessels, was a monozygotic twin which developed within its own amniotic cavity.     

Genetic engineering of coryneform bacteria

The coryneforms are a diverse group of bacteria which includes animal and plant pathogens as well as non-pathogenic bacteria. Although they are of significant economic and health importance, their genetics is poorly understood. The development of genetic engineering techniques for coryneforms and initial gene cloning studies are discussed.     

Effects of short-term treatment with calcium on the parathyroid gland of the rat,under particular consideration of the alteration of storage granules

Summary Short-term effects of CaCl₂-treatment on parathyroid cells of the rat, especially on their storage granules, were studied at the ultrastructural level. After an injection of 4% CaCl₂, serum calcium levels (SCL) rapidly increased from 9.1 mg/dl (controls) to a maximum of 14.9 mg/dl at 20 min. At 5 min after the injection, the number of type-I storage granules (large core) [NSG-I] and that of type-II storage granules (small core) [NSG-II] remained unchanged, in spite of elevated SCL (12.4 mg/dl). As soon as SCL rose to 13.2 mg/dl at 7.5 min, NSG-I gradually decreased to a minimum at 30 min; in contrast, NSG-II gradually increased to a maximum at 30 min. Vacuolar bodies also increased together with the augmentation of type-II storage granules. The average diameter of the core of the storage granules decreased significantly after the injection. Protein A-gold method for immunocytochemistry showed that the cores of these granules contain parathormone. Acid-phosphatase activity was occasionally found in storage granules of both types, especially in those of type II. It is concluded (i) that type-I storage granules may be transformed into vacuolar bodies via type-II granules as a result of hydrolysis, and (ii) that these processes may be accelerated during hypercalcemia.     

A novel cell-surface antigen expressed on most leukocytes and a minor cortisone-resistant population of thymocytes in rats: characterization by monoclonal antibodies

A cell-surface antigen on rat lympho-hemopoietic cells was determined by using a monoclonal antibody, R2-1B3 (1B3). The 1B3 antibody, when tested for its reactivity with different hemopoietic cells by cytofluorography with a FACS analyzer, labeled more than 80% of lymph node, spleen, and bone marrow cells and 10-20% of thymus cells. Cytofluorographic analysis performed on purified rat T cells, B cells, macrophages, and granulocytes demonstrated that the antigen defined by 1B3 was readily detectable on all of these cell types, with the greatest expression on B cells. A minor population of thymocytes that were labeled by 1B3 appeared to be cortisone-resistant and were located mainly in the thymic medulla. These 1B3 positive thymic cells seemed to be functionally more mature than 1B3-negative thymus cells as suggested by the fact that the cytotoxic treatment of thymus cells with 1B3 antibody and complement (C) resulted in significant reduction of their responsiveness to phytomitogens and lymphokines derived from concanavalin A (con A) activated rat spleen cell cultures. Immunochemical data showed that 1B3 antibody recognized the broad ill-defined band with a molecular weight of 32K to 47K daltons as estimated by SDS-polyacrylamide gel electrophoresis. These data indicate that the 1B3 defined antigen is distinct from other, previously reported, antigens on rat lymphoid cells including leukocyte-common (L-C) and MRC OX-22 antigens, and that this 1B3 antibody is a useful reagent for analyzing the intrathymic differentiation of T cells in rats.     

False positive reaction for carcinoembryonic antigen in paget cells

Virchows Archiv B Cell Pathology - Paget cells from cases of mammary and extramammary Paget’s disease were examined for carcinoembryonic antigen (CEA) and CEA-related antigens by the...     

Direct evidence for the existence of nominal antigen binding sites on T cell surface Ti alpha-beta heterodimers of MHC-restricted T cell clones

The binding of nominal antigen to Ti alpha-beta heterodimers on MHC-restricted human T cell clones specific for fluorescein-5-isothiocyanate (FL) was detected by flow cytometry and affinity chromatography. The FL-Ti interaction is of physiologic significance, since T cell activation is induced by cross-linked arrays of FL in the absence of the specific MHC recognition. High antigen valence is required to achieve stable binding to cells and subsequent activation, which is consistent with estimated Ti-FL association constants of less than 3 X 10(5) l/mol. In addition to providing direct evidence that the Ti alpha-beta heterodimer is the receptor for antigen, these data suggest that nominal antigen binding sites exist on the Ti molecules of at least some MHC-restricted clones.     

Metabolism of apolipoprotein E-containing human plasma lipoproteins by rat and human cells in culture.

Cultured preadipocytes from rat epididymal fat pads were able to bind, internalize, and degrade human plasma very-low-density lipoproteins (VLDL) more efficiently than low-density lipoproteins (LDL). VLDL, but not LDL, activated acyl-CoA: cholesterol acyltransferase (ACAT) and increased cholesterol accumulation in these cells. However, trypsin-treated VLDL (T-VLDL) lost the capacity to bind, activate ACAT, and increase cholesterol accumulation. After the treatment of VLDL with trypsin, SDS/polyacrylamide-gel electrophoresis and immunoblotting showed that apolipoprotein E (apo E) was completely degraded, whereas apolipoprotein CII (apo C-II) was preserved. ApoE complexed with dimyristoyl phosphatidylcholine (DMPC) was able to complete with VLDL for binding to the cells. Although T-VLDL did not bind to the preadipocytes, these cells accumulate triacylglycerols from T-VLDL, presumably after lipolysis, as efficiently as from native VLDL. Rat smooth muscle cells and skin fibroblasts also bind and metabolize human VLDL better than LDL. However, human skin fibroblasts and omental preadipocytes metabolized LDL better than VLDL. These studies indicate that rat tissues can recognize and metabolize apoE-containing human plasma VLDL although they cannot recognize human LDL.