Aneurysms after microvascular anastomoses. Incidence and pathogenesis in experimental animals.

This study has demonstrated that aneurysms occur in about 50 percent of the rat femoral arteries subjected to microvascular anastomosis. These aneurysms are consistent histologically--being characterized by medial necrosis, loss of elastic lamellae, and subintimal hyperplasia. Mechanical trauma is implicated as a factor in their pathogenesis, though further study in necessary to define the exact etiology.     

Uranium-series ages of marine terraces,La Paz Peninsula,Baja California Sur,Mexico

Uranium-series dating of coral samples from raised marine terrace deposits between 1.5 and 10 m above sea level in the La Paz Peninsula area, Baja California Sur, yielded ages between 123 ka and 138 ka that are in agreement with previously reported results. The stratigraphy and ages of marine units near the El Coyote Arroyo indicate the presence of two high stands of the sea during the last interglacial or oxygen isotope substage 5e at about 140 ka and 123 ka. Accepting 5 m for the sea level during the last interglacial transgression, we calculate average uplift rates for the marine terraces of about 70 mm/ka and 40 mm/ka. These slow rates of uplift indicate a relative stability of the La Paz peninsula area for the past 140 000 years. In contrast, areas of Baja California affected by major faultf experienced higher rates of uplift. Rockwell et al. (1987) reported vertical uplift rates of 180 to 300 mm/ka at Punta Banda within the Aqua Blanea fault zone in northern Baja California.     

Rapid hydrophobic grid membrane filter-enzyme-labeled antibody procedure for identification and enumeration of Escherichia coli O157 in foods

An O-antigen-specific monoclonal antibody, labeled by horseradish peroxidase-protein A, was used in a hydrophobic grid membrane filter-enzyme-labeled antibody method for rapid detection of Escherichia coli O157 in foods. The method yielded presumptive identification within 24 h and recovered, on average, 95% of E. coli O157:H7 artificially inoculated into comminuted beef, veal, pork, chicken giblets, and chicken carcass washings. In food samples from two outbreaks involving E. coli O157:H7, the organism was isolated at levels of up to 10(3)/g. The lower limit of sensitivity was 10 E. coli O157 per g of meat. Specific typing for E. coli O157:H7 can be achieved through staining with labeled H7 antiserum or tube agglutination.     

The bovine insulin-like growth factor (IGF) binding protein purified from conditioned medium requires the N-terminal tripeptide in IGF-1 for binding

The insulin-like growth factor binding protein (BP) secreted by bovine kidney (MDBK) cells has been purified by affinity chromatography on a rat IGF-2 Sepharose column. Purified BP migrated as a single band of Mr 40,000 upon SDS polyacrylamide gel electrophoresis. An N-terminal sequence of 53 residues was obtained which was very similar up to residue 21 to the corresponding rat BRL-3A BP sequence. In competitive binding experiments with bovine IGF-1 and IGF-2, and recombinant human IGF-1, BP had a similar affinity for these ligand when IGF-1 tracer was used, but a higher affinity for IGF-2 with IGF-2 as radioligand. The N-terminal destripeptide truncated form of bovine IGF-1, which has enhanced biological activity, was found to have a markedly reduced affinity for BP compared to intact IGF-1. The increased bioactivity of destripeptide IGF-1 can be explained by this reduced affinity for BP.     

Murine erythroleukemia cell variants: isolation of cells that have amplified the dihydrofolate reductase gene and retained the ability to be induced to differentiate

A series of murine erythroleukemia cell (MELC) variants was generated by selection for the ability to grow in increasing concentrations of the folate antagonist methotrexate (MTX). Growth of the parental MELC strain DS-19 was completely inhibited by 0.1 microM MTX. We isolated cells able to grow in 5, 40, 200, 400, and 800 microM MTX. Growth rates and yields were essentially the same in the presence or absence of the selective dose of MTX for all variants. MTX resistance was not the result of a transport defect. Dihydrofolate reductase (DHFR) from our variants and DS-19 was inhibited to the same extent by MTX. Variants had increased dihydrofolate reductase activities. The specific activity of DHFR was proportional to the selective concentration of MTX employed to isolate a given variant. DNA dot blotting established that the cloned variant (MR400-3) had a 160-fold increase in DHFR gene copy number relative to the parental strain (DS-19). Hybridization studies performed in situ established the presence of amplified DHFR genes on the chromosomes of the MTX-resistant but not the MTX-sensitive (parental) cells. Quantitation of DHFR mRNA by cytoplasmic dot blotting established that the amplified DHFR gene expression was proportional to gene copy number. Thus, MTX resistance was due to amplification of the DHFR gene. The variants retained the ability to be induced to differentiate in response to dimethyl sulfoxide and hexamethylenebis(acetamide) as evaluated by the criteria of globin mRNA accumulation, hemoglobin accumulation, cell volume decreases, and terminal cell division.(ABSTRACT TRUNCATED AT 250 WORDS)     

Integration and excision of pMC7105 in Pseudomonas syringae pv. phaseolicola: involvement of repetitive sequences.

The site for integration of pMC7105 into the chromosome of Pseudomonas syringae pv. phaseolicola has been mapped to a 2.6-kilobase-pair (kb) Bg/II-EcoRI fragment on this 150-kb indigenous plasmid. Selected excision plasmids resulting from imprecise excision of pMC7105 were used to identify one of the plasmid-chromosome juncture fragments and to characterize the mechanism of recombination from the chromosome. A 14.2-kb BamHI plasmid-chromosome juncture fragment has been identified in pEX8060 (234 kb), an excision plasmid which carries approximately 90 kb of chromosomal sequences to the left of the site of integration. This fragment contains a portion of the 2.6-kb Bg/II-EcoRI fragment as well as chromosomal sequences. Blot hybridization with a probe made from selected fragments of pMC7105 revealed three distinct repetitive sequences, RS-I, RS-II, and RS-III, on this plasmid. The 2.6-kb fragment, to which the site of integration maps, also contains RS-II. Five copies of RS-II are present in pMC7105, and more than 20 copies are present in the chromosome. Eight small excision plasmids were shown to result from recombination among fragments of pMC7105 that contain common repetitive sequences. The results indicate that integration and excision of pMC7105 occur through general recombination at homologous repetitive sequences.     

Intratracheal instillation of a novel NO/nucleophile adduct selectively reduces pulmonary hypertension

Brilli, Richard J., Brian Krafte-Jacobs, Daniel J. Smith,Dominick Roselle, Daniel Passerini, Amos Vromen, Lori Moore, CsabaSzabó, and Andrew L. Salzman. Intratracheal instillation ofa novel NO/nucleophile adduct selectively reduces pulmonary hypertension. J. Appl. Physiol. 83(6):1968-1975, 1997.We examined the pulmonary and systemichemodynamic effects of administering soluble nitric oxide (NO) donorcompounds (NO/nucleophile adducts, i.e., NONOates) directly into thetrachea of animals with experimentally induced pulmonary hypertension.Steady-state pulmonary hypertension was created by using thethromboxane agonist U-46619. Yorkshire pigs were randomly assigned toone of four groups: group 1,intratracheal saline (control; n = 8);group 2, intratracheal sodiumnitroprusside (n = 6);group 3, intratracheal ethylputreanineNONOate (n = 6); andgroup 4, intratracheal2-(dimethylamino)-ethylputreanine NONOate (DMAEP/NO;n = 6). Pulmonary and systemichemodynamics were monitored after drug instillation.Group 4 had significant reductions in pulmonary vascular resistance index (PVRI) at all time points comparedwith steady state and compared with group1 (P < 0.05), whereas systemic vascular resistance index did not change. The meanchange in mean pulmonary arterial pressure in group4 was 33.1 ± 1.2% compared with +6.4 ± 1.3% in group 1 (P < 0.001), and the mean change inmean arterial pressure was 9.3 ± 0.7% compared with acontrol value of 0.9 ± 0.5%(P < 0.05). Groups 2 and 3 hadsignificant decreases in both PVRI and systemic vascular resistanceindex compared with steady state and with group1. In conclusion, intratracheal instillation of apolar-charged tertiary amine NONOate DMAEP/NO results in the selectivereduction of PVRI. Intermittent intratracheal instillation of selectiveNONOates may be an alternative to continuously inhaled NO in thetreatment of pulmonary hypertension.

     

Isolation and subregional mapping of a human cDNA clone detecting a common RELP on chromosome 12

Summary Peripheral blood lymphocytes from three patients with Down syndrome (DS; trisomy 21; aged 5–6 years) and three age-matched control children were studied for the induction of chromosomal aberrations and sister chromatid exchanges (SCEs).Cells in G₀ were exposed to bleomycin (20–100 g/ml) for 3 h, and then cultured in medium containing 5-bromodeoxyuridine and phytohemagglutinin for 66 h. By the sister chromatid differential staining method, chromosome analyses were performed on metaphase cells that had divided one, two, or three or more times after treatment. The results indicate that DS cells exposed to bleomycin are hypersensitive to the production of dicentric and ring chromosomes compared to normal cells. Bleomycin also led to a dose-related increase in the frequency of SCEs, but no difference was found between the SCE frequencies in DS or normal lymphocytes exposed to bleomycin.     

The gene for the alpha polypeptide of pyruvate dehydrogenase is X-linked in humans.

The chromosomal location of the gene for the alpha polypeptide of the pyruvate dehydrogenase (alpha E1), a major component of the pyruvate dehydrogenase complex, was determined by using a cloned cDNA for alpha E1. This 1-kb cDNA was isolated from a human liver lambda gt11 expression library with specific antibodies and included the coding (from amino acid 144 to the carboxy terminus) and the 3' untranslated regions. Southern blot analysis of the DNA from a panel of rodent-human hybrid cells showed that the absence or the presence of the major EcoRI fragment that hybridized with this cDNA probe was concordant with the presence of the Xq24-p22 region of the human X chromosome. The result of in situ hybridization with human metaphase chromosomes further mapped the alpha E1 gene to the Xp arm.