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Biomedical subjects

H Laufer

Publications and source records attributed to H Laufer.

At least 37 records · Page 2Linked to original sources
PubMed1984

Changes in template activity of protein and globin mRNA during Chironomus development.

A wheat-germ cell-free protein synthesizing system was established that efficiently translates fourth instar mRNA from Chironomus thummi. The translation products were analyzed by double immunoprecipitation with specific antibodies against Chironomus hemoglobins. The predominant translation products were shown to be globins, comprising about 50% of total protein synthesized. Two globins, globins 2 and 3, which are specific for the fourth instar in vivo, constitute most of the globin produced. The wheatgerm system translates also efficiently total cytoplasmic RNA, purified from animals at successive developmental stages. The kinetics of protein synthesis during development indicate that Chironomus mRNA template activity is low during larval molting and at metamorphosis. RNA from intermolt larvae generally demonstrates high template activity. In the fourth instar two distinct peaks of activity are resolved, one associated with newly molted fourth instars and a second one associated with the prepupal stage. These RNAs direct the synthesis mostly of non-globin proteins. Immunoprecipitation of the translation products shows that globin synthesis is high in intermolt larvae decreasing to very low, or background levels in larvae molting or metamorphosing to pupae. Globins 2 and 3 are synthesized exclusively by newly synthesized globin transcripts in the fourth instar stage. The results show stage-specific translational activity of globin mRNAs during Chironomus development and suggest hormonal control of globin production.

Animals↗
PubMed1984

Regulation of hemoglobin synthesis by ecdysterone and juvenile hormone during development of Chironomus thummi (Diptera).

Chironomus thummi contains nine soluble hemoglobins (Hbs) in the larval hemolymph which can be resolved by 12.7% acrylamide gel electrophoresis (pH 8.65). Hemoglobins 2 and 3 are stage specific for the 4th instar and are first detected by day 4 of this stage in vivo, being absent in the 3rd instar. Fat-body cultures in the presence of 3H-delta-aminolevulinic acid and 14C-amino acids synthesize and secrete labelled Hbs, as was assayed by acrylamide gel electrophoresis and immunoprecipitation of Hbs recovered from the culture medium. During development from 3rd instar to pupa, Chironomus fat body undergoes functional changes, being actively involved in Hb synthesis in intermolt periods and inactive with respect to Hb production during molting. The repression of Hb synthesis is reversed following the molt from the 3rd instar to the 4th instar. Metamorphosis is related to a gradual and irreversible loss of Hb synthesis and secretion by the fat body. The treatment of fat body in vitro with ecdysterone inhibits Hb synthesis in tissue from intermolt animals, even in the presence of excess methoprene, a potent juvenile hormone analogue. In contrast, immunoprecipitation of the translation products from a wheat-germ cell-free system, using mRNA from ecdysterone-treated 4th-instar fat body as a template, shows significant synthesis of globins, suggesting that ecdysterone does not affect the amount or template activity of globin messages. Methoprene induces the precocious in vitro synthesis of Hbs 2 and 3 in day-2 4th-instar fat body and enhances all Hb synthesis in the absence of ecdysterone. In vitro treatment with methoprene activates newly molted fat body to synthesize Hbs 2 and 3 in vitro. The process of Hb induction by this analogue is completely inhibited by actinomycin D or ecdysterone. Fat body from animals already exposed to high endogeneous ecdysterone titer are insensitive to treatment with this juvenile hormone analogue. Intermolt larvae normally possess stable Hb mRNA molecules, because actinomycin-D administration in vitro does not affect Hb synthesis for as long as 30 h, whereas it effectively inhibits all RNA synthesis in the fat body. Immunoprecipitation of globin translated in vitro from mRNA from 2-day-old 4th-instar larvae treated in vivo with methoprene shows enhanced synthesis of globins 2 and 3, as compared to controls with no treatment. It is suggested that both juvenile hormone and ecdysterone regulate Hb synthesis in Chironomus; juvenile hormone affecting the activity of Hb genes, and ecdysterone modulating the level of Hb gene expression.

Animals↗
PubMed1981

Hepatic and appendiceal Whipple's disease with negative jejunal biopsies.

A 20-year-old man with Whipple's disease, right upper quadrant pain, abnormal liver tests and multiple negative peroral small bowel biopsies is presented. The patient underwent laparotomy: foamy macrophages were noted in the appendix and mesenteric lymph nodes; using electron microscopy, bacillary bodies were seen in the appendix, the mesenteric lymph node, and the liver. This patient had the rare occurrence of Whipple's disease of the appendix with bacillary bodies in the liver and a clinical picture compatible with hepatic involvement or cholangitis and a slow response to conventional antibiotic therapy.

Adult↗
PubMed1978

Fine structure of a cerebellar neuroblastoma.

A cerebellar neoplasm of an 18-month-old boy was examined with both the light and electron microscopes. The diagnosis of neuroblastoma was made on the basis of the presence of numerous synaptic vesicles in the great majority of cell processes and the occasional complete synapses within the tumor tissue.

Cerebellar Neoplasms↗
PubMed1976

Fat body: a site of hemoglobin synthesis in Chironomus thummi (diptera).

Fourth instar larvae of Chironomus thummi were permitted to incorporate labeled amino acids and/or sigma-aminolevulinic acid (sigma-ALA) in vivo and in organ culture. The products secreted into the hemolymph or into the culture medium were examined by acrylamide gel electrophoresis. Nine electrophoretic bands can be resolved as hemoglobins without staining. When gels are sliced for scintillation counting, incorporated amino acids and sigma-ALA are shown to be associated primarily with the same nine hemoglobin bands, suggesting that hemoglobins are assembled and secreted. Staining of gels with Coomassie brilliant blue reveals that there are several bands in addition to the visible hemoglobins. These bands incorporate amino acids, but not sigma-ALA, suggesting that they are non-heme proteins. The results of culturing isolated salivary glands, gut, and fat body demonstrate that the fat body is the major site of hemoglobin synthesis and secretion. Labeled products of the gut represent about 5% of the total hemoglobins produced by the tissues, while no hemoglobins are produced by the salivary glands. Although nine hemoglobins are visibly resolved on gels, labeling techniques reveal as many as 14 hemoglobins. This is the first demonstration of hemoglobin synthesis by specific tissues in culture in an invertebrate.

Adipose Tissue↗