In vitro replication of recombinant plasmids carrying chromosomal segments of Xenopus laevis

Recombinant plasmids carrying a segment of Xenopus laevis chromosomal DNA were constructed with plasmid pBR322 as the vector. A recombinant plasmid pXY65 carrying a 3.2-kilobase BamHI segment of the chromosome of X. laevis has been found to contain a repetitive sequence dispersed throughout the X. laevis chromosomes. This plasmid initiated replication in vitro when the supercoiled circular molecules were incubated in a replication system. The other recombinant plasmids tested and the pBR322 vector were not replicated. Electron microscopic analysis of the replicative intermediates showed that the replication was initiated at a specific site in the 3.2-kilobase BamHI segment of pXY65 and that the replication usually proceeded bidirectionally. Analysis of the reaction products by centrifugation in alkaline sucrose gradients indicated that short pieces were synthesized in the in vitro replication system. DNA synthesis was inhibited in vitro by the addition of aphidicolin and by omission of dNTPs. These results indicate that the X. laevis segment cloned in pXY65 contains a site capable of initiating replication in vitro.

Effects of vagotomy and gastrectomy on pancreatic glucagon release

The effects of gastrectomy and vagotomy on pancreatic glucagon release were investigated clinically. The study included 20 men and eight women, who ranged in age from 28 to 69 years, and who were divided into the following four groups: 1) patients with gastroduodenal ulcers treated with partial gastrectomy, by the Billroth I method, whose hepatic branch was preserved (n = 7). 2) Patients with gastroduodenal ulcers treated with partial gastrectomy, by the Billroth II method, whose hepatic branch was preserved (n = 7). 3) Patients with gastric carcinoma treated with subtotal gastrectomy, by the Billroth I method. In these cases lymphadenectomy required section of the hepatic branch (n = 7). 4) Patients with gastric carcinoma treated with subtotal gastrectomy, by the Billroth II method. In these cases lymphadenectomy required section of the hepatic branch (n = 7). Oral glucose tolerance tests were performed in 10 patients, before operation, and in 28 gastrectomized and vagotomized patients. In the preoperative patients and in the first group, oral glucose (50g) suppressed pancreatic glucagon release, but in the other groups pancreatic glucagon levels were markedly increased.

Chemical test of phosphates in urinary stones by means of the chromatographic contact print method

The chromatographic contact print method, making use of the ammonium phosphomolybdate-ascorbic acid reaction, is used to detect phosphates and to view their distribution in urinary stones. This sensitive reaction may take place even if phosphates, especially apatite, are present in such small amounts as to be under the confirmation limits of microscopic observation, and X-ray and infrared analyses.

Microheterogeneity among carbohydrate structures at the cell surface may be important in recognition phenomena

Independently derived mutants of Chinese hamster ovary cells have been isolated and shown to exhibit a subtle glycosylation defect resulting in the premature termination of certain asparagine-linked carbohydrate moieties. This carbohydrate alteration is akin to the types of structural variation termed microheterogeneity and is thought not to affect the biological activities of glycoproteins that manifest the phenomenon. However, the carbohydrate change expressed by the mutants is stable and heritable, and 125I-lectin-binding studies suggest that it profoundly alters their surface recognition properties. The mutation appears to affect a specific subpopulation of galactose residues in asparagine-linked carbohydrate of the type found associated with the G glycoprotein of vesicular stomatitis virus. The mutant cells also exhibit morphological changes in substratum culture.

Effect of CaCl2 on production of interferon and synthesis of its mRNA in human MG-63 cells

The effect of excess CaCl2 addition on the production of interferon and synthesis of its mRNA in a human cell line was investigated. Human MG-63 cells which were treated with 7 mM CaCl2 after poly(rI).poly(rC) induction produced 3 to 10 times as much interferon as control cells. Increased interferon mRNA activity was obtained from CaCl2 treated cells, suggesting that there was an increased interferon mRNA production in these cells.

Changes in plasma glucagon after total pancreatectomy in man

Changes in the blood glucagon reactive to 30K antibody were followed in two patients before, during, and after total pancreatectomy. The blood glucagon level was decreased six hours after the operation, and then increased gradually unless insulin was administered. The increased non-pancreas glucagon was immediately suppressed by insulin administration. The glucagon secretion response to an arginine load was already low one week after the operation, and was absent even three weeks after the operation.

Acute diffuse phlegmonous gastritis

A case of acute diffuse phlegmonous gastritis in a 54 year old man with an abrupt onset of upper abdominal pain, high fever and complete anorexia was presented. The stomach wall was remarkably thickened and rigid. Histologically there was massive infiltration of polymorphonuclear leukocytes in the submucosa and muscularis of the stomach wall. The lamina muscularis mucosae was fragmented by the numerous small focal abscesses.

Differential involvement of cell surface sialic acid residues in wheat germ agglutinin binding to parental and wheat germ agglutinin-resistant Chinese hamster ovary cells

Two Chinese hamster ovary (CHO) cell mutants selected for resistance to wheat germ agglutinin (WGA) have been shown to exhibit defective sialylation of membrane glycoproteins and a membrane glycolipid, GM3. The mutants (termed WgaRII and WgaRIII) have been previously shown to belong to different genetic complementation groups and to exhibit different WGA-binding abilities. These mutants and a WGA-resistant CHO cell mutant termed WgaRI (which also possesses a surface sialylation defect arising from a deficient N-acetylglucosaminyltransferase activity), have enabled us to investigate the role of sialic acid in WGA binding at the cell surface. Scatchard plots of the binding of 125I-WGA (1 ng/ml to 1 mg/ml) to parental and WgaR CHO cells before and after a brief treatment with neuraminidase provide evidence for several different groups of sialic acid residues at the CHO cell surface which may be distinquished by their differential involvement in WGA binding to CHO cells.

Mineralogical notes of apatite in urinary calculi

Apatite in some samples of common urinary calculi consisting mainly of apatite or of calcium oxalate and apatite was subjected to X-ray and thermal analysis and electron microscopic investigation. The X-ray analysis has determined the lattice parameters agreeing with hydroxyapatite, and the mean crystallite size normal to the basal plane in a range of 200-800 A. The thermal analysis is given by differential thermal analysis (DTA) and thermogravimetric (TG) curves. From the TG curve of a mixed apatite-calcium oxalate calculus, an approach is given to estimate the proportions of the constituent materials; the result is as follows: whewellite, 51.7%; weddellite, 16.6%; apatite, 19.1%; and organic materials, 12.6%. Analysis with the scanning electron microscope with energy dispersive X-ray spectrometer has shown that apatite is found as tiny spherules (5-10 micrometer in diameter) with fluffy surfaces resulting from projecting fine fibers or needles (about 0.5 micrometers in length). The fibers are considered to be mosaic aggregates of crystallites. The spherules fill interspaces of well-formed oxalate crystals or are included sporadically in individual crystals. Occasionally well-formed crystal-shaped oxalates are bordered with narrow bands consisting of apatite spherules (often as hemispheres) linked in a row.

Isolation and characterization of tunicamycin resistant mutants from Chinese hamster ovary cells

Stable clones selected for resistance to tunicamycin (TM) have been isolated from Chinese Hamster Ovary (CHO) cells. The TMR phenotype is stable for more than nine months in the absence of the drug. The morphology of TMR mutant varies from epitheloid to abnormally elongate. The mutants do not display cross-resistance for ConA but are slightly cross-resistant to PHA. Biochemically labeled membrane proteins and glycoprotein of Vesicular stomatitis virus (VSV) grown in the TMR mutants revealed that the incorporation of radioactive glucosamine was markedly reduced in the mutants. The results indicate that TMR cells are a novel type of membrane mutant.

Effect of exogenously administered glucagon on plasma glucose levels in totally depancreatized dogs

Glucagon was administered exogenously via a subcutaneous route to totally depancreatized adult mongrel dogs and studies were made with major emphasis on glucagon effect on the plasma glucose levels. 1. In the totally depancreatized dogs, the plasma glucose levels determined 90 minutes after glucagon injection (40 micrograms/kg s.c.). were compared with the pretreatment fasting plasma glucose levels. The rate of increase in the plasma glucose levels was 5.13 +/- 0.48 times (M +/- SEM) in dogs with low pretreatment level (lower than 100 mg/dl). In dogs with higher pretreatment levels (100-400 mg/dl), the increase was 1.62 +/- 0.40 times. And in dogs with the pretreatment levels higher than 400 mg/dl, the value was 0.90 +/- .07 times. 2. Ninety minutes after regular insulin injection (0.25 U/kg i.v.), glucagon was administered (40 micrograms/kg s.c.), and the changes in the plasma glucose levels were determined. 3. In totally depancreatized dogs, a transient increase in the plasma insulin level was noted when glucagon was administered (40 micrograms/kg s.c.) under infusion of a mixture of glucose and insulin. 4. There was no significant difference in the rate of disappearance of glucagon from the blood between normal and totally depancreatized dogs. 5. It is considered that glucagon would be useful for the treatment of hypoglycemia encountered after total pancreatectomy.