Pulmonary vascular pressure profiles in broilers selected for susceptibility to pulmonary hypertension syndrome: age and sex comparisons.

Broilers that are susceptible to pulmonary hypertension syndrome (PHS, ascites) have an elevated pulmonary arterial pressure (PAP) when compared with PHS-resistant broilers. Two distinctly different syndromes, pulmonary arterial hypertension and pulmonary venous hypertension (PVH), both are associated with increases in PAP. Pulmonary arterial hypertension occurs when the right ventricle must elevate the PAP to overcome increased resistance to flow through restrictive pulmonary arterioles upstream from the pulmonary capillaries. In contrast, PVH is commonly caused by increased downstream (postcapillary) resistance. The sites of resistance to pulmonary blood flow are deduced by making contemporaneous measurements of the PAP and the wedge pressure (WP) and calculating the transpulmonary pressure gradient (TPG) (TPG = PAP - WP). We obtained PAP and WP values from 8-, 12-, 16-, 20-, and 24-wk-old anesthetized male and female broilers from a PHS-susceptible line. Pressures were recorded as a catheter was advanced through a wing vein to the pulmonary artery and onward until the WP was obtained. In addition to sex and age comparisons of vascular pressure gradients, the data also were pooled to obtain 3 cohorts for broilers having the lowest PAP values (n = 52; range: 12 to 22.9 mmHg), intermediate PAP values (n = 63; range: 23 to 32.9 mmHg), and highest PAP values (n = 62; range: 33 to 62 mmHg) independent of age or sex. Within each of the age, sex, and PAP cohort comparisons, broilers with elevated PAP consistently exhibited the hemodynamic characteristics of pulmonary arterial hypertension (elevated PAP and TPG combined with a normal WP) and not PVH (elevated PAP and WP combined with a normal or reduced TPG). Susceptibility to PHS can be attributed primarily to pulmonary arterial hypertension associated with increased precapillary (arteriole) resistance.

Synthesis and characterization of new oxidopolysulfidovanadates.

The alkali-metal oxidopolysulfidovanadates Cs(4)[(VO)(2)(eta(2)-S(2))(4)(mu-S(2))] (I), Cs(5)[(VO)(3)(eta(2)-S(2))(6)(mu-S(4))] (II), and K(6)[(VO)(4)(eta(2)-S(2))(8)(mu-S(3))].2CH(3)OH.0.6H(2)O (III) have been synthesized by means of methanothermal methods at 170 degrees C or 175 degrees C. These compounds each contain a V(5+) ion coordinated by an oxo ligand and two eta(2)-S(2)(2-) groups. In I, two such [VO(eta(2)-S(2))(2)](-) units are bridged by an S(2)(2)(-) unit. In II and III, two such [VO(eta(2)-S(2))(2)](-) units are joined by a V-S-V bond to form [(VO(eta(2)-S(2))(2))(2)](2-) units; in II, such a [(VO(eta(2)-S(2))(2))(2)](2-) unit is bridged to a [VO(eta(2)-S(2))(2)](-) unit by an S(4)(2-) group; in III, two such [(VO(eta(2)-S(2))(2))(2)](2-) units are bridged by an S(3)(2-) group. Crystallographic data at T = 153 K (compound, space group, Z, a, b, c, beta): I, P2(1)/n, 2, 7.4366(3), 10.3743(5), 13.1151(6) A, 101.097(1) degrees; II, P2(1)/c, 4, 8.4451(6), 24.5144(18), 14.0995(10) A, 101.325(1) degrees; III, C2/c, 4, 31.037(3), 12.5355(11), 8.7822(8) A, 93.127(2) degrees.

Gentamicin-resistance plasmids in an intensive care unit.

To better understand the role of plasmids and their importance in the endemic antibiotic resistance of Enterobacteriaceae, we began a prospective study of our combined medical intensive care/coronary care unit. An initial culture survey of the patients, ward staff, and environment was followed by a prospective sampling of 139 consecutive new admissions at the time of admission to the unit, and at regular intervals thereafter for the remainder of their stay. All cultures were planted on agar-containing gentamicin. Of the 147 patients studied, 12 (8.2%) were colonized with 20 strains of gentamicin-resistant gram-negative bacilli (GRGNB) at 29 sites. An additional four GRGNB were isolated from the environment. Of the 24 GRGNB strains, 7 (29%) Enterobacteriaceae carried plasmids shown to carry the gentamicin-resistance determinant. Plasmids were further characterized by restriction endonuclease digestion profiles of plasmid DNA purified from E. coli C600 transconjugants or transformants. A 93 kb plasmid introduced to the unit by a Serratia liquefaciens colonizing a patient transferred from another area in the hospital was identical to 93 kb plasmids carried by a C. amalonaticus and an E. aerogenes subsequently colonizing another patient on the unit. A 60 kb plasmid, first isolated from a S. marcescens colonizing a sink drain was later isolated from an E. cloacae colonizing a patient. Our results indicate that spread of specific R-plasmids may be one mechanism for dissemination of antibiotic resistance on our MICU/CCU.

Epidemiology of gentamicin-resistant, gram-negative bacillary colonization in a spinal cord injury unit.

A prospective epidemiological survey of a spinal cord injury unit for gentamicin-resistant, gram-negative bacilli was undertaken. The initial survey of the unit suggested a low level of cross-infection involving Pseudomonas aeruginosa and Providencia stuartii. However, a longitudinal study of new admissions revealed that only 13 of 52 nosocomial acquisitions could be considered to be due to cross colonization. Comparison of data on antibiotic use did not suggest selective pressure for resistant endogenous flora. Nosocomial acquisition was directly related to the length of the hospital stay. Antibiotic susceptibility testing of gentamicin-resistant, gram-negative bacilli showed only minor differences between nosocomial isolates and those present during the initial survey. Of the usual antimicrobial agents, amikacin, carbenicillin, and cefoxitin were the most active against all organisms, with the exception of Serratia spp. Of the new beta-lactams, ceftazidime and imipemide (N-formimidoyl thienamycin) were most active.