Plasma marinobufagenin-like and ouabain-like immunoreactivity during saline volume expansion in anesthetized dogs

OBJECTIVES: This study investigated effects of acute plasma volume expansion on plasma levels and urinary output of two endogenous Na,K-ATPase inhibitors, marinobufagenin-like and ouabain-like immunoreactive substances. METHODS: Plasma volume was expanded for 3 h via intravenous saline infusion in three groups of anesthetized dogs--nontreated (n = 5); pretreated with rabbit antidigoxin (n = 5); and pretreated with rabbit antimouse (control) antibody (n = 4). RESULTS: Plasma marinobufagenin-like immunoreactivity increased to 11.87 +/- 3.16 nmol.l-1 (vs. 0.30 +/- 0.16 nmol.l-1) within 10 min of volume expansion, in parallel with a 15% increase in LVdP/dt, then decreased to 2.21 +/- 0.59 nmol.l-1, and in 90 min increased to 11.8 +/- 2.8 nmol.l-1, in parallel with the maximal natriuretic response. Plasma concentrations of ouabain-like immunoreactive material were increased after 90 min of saline infusion (0.019 +/- 0.004 nmol.l-1 vs. 0.139 +/- 0.056 nmol.l-1). Pretreatment of the animals with antidigoxin antibody blocked the positive inotropic and reduced natriuretic response to volume expansion, and decreased the urinary release of marinobufagenin-like, but not ouabain-like, material. CONCLUSIONS: These results show the presence of marinobufagenin-like immunoreactive substance in dog plasma and suggest that mammalian EDLF may have a bufodienolide nature. Endogenous marinobufagenin-like immunoreactive substance, which is likely to cross-react with antidigoxin antibody, is involved in the natriuretic and positive inotropic responses to plasma volume expansion.     

Units of DNA replication in S-phase human cells

Current methods of physical mapping allow the estimation of genomic distances (i.e. DNA contents) from linear distances between DNA markers in interphase nuclei, and in this study we estimated the size of focal centers of DNA replication in cultured S-phase human cells. Our results indicate that the conformation of S-phase chromosome fibres in the range of contour lengths 0.1-3.0 microns fits the random walk model and, therefore, the quantitative methods of interphase mapping can be applied to the estimation of sizes of replication units. The obtained data show the existence of multiple non-clustered small units less than 150 kb in size, equivalent to small replicons detected by fiber DNA radioautography, and also a significant fraction of big units more than 500 kb in size, representing groups of small replicons and/or big replicons. These big units are detected as chains of small replication foci, probably reflecting the structural chromatin organization in well-known loop domains, since the experimentally induced decrease of replicons to the average size 12 kb does not lead to any change in the pattern of indicated chains.     

Detection of K-ras point mutation by in situ PCR in cell suspensions: comparison of the indirect and direct methods

In situ PCR is a new technique for the localization of low copy number sequences. We report here a method for the in situ visualization of a point mutation in K-ras codon 12 by indirect in situ PCR. Twenty-five primers were examined to select mutant-specific primers. Harvested cell lines were fixed and suspended in PCR mixture. Forty cycles of PCR in cell suspension was performed in a thermal cycler using a hot start method. Cells were cytocentrifuged onto slides, and post-fixation was performed. The specimens on the slides were then hybridized with a digoxigenin-labeled probe, followed by color reaction. Both Calu-1 (mutated: TGT) and NCI-H460 (wild type: GGT) cells had strong hybridization signals in the nuclei with general primers. But with mutant-specific primers, only Calu-1 cells had hybridization signals. No signal was observed without primers or Taq DNA polymerase. Southern blotting of the same preparation confirmed desired amplification. We also applied direct in situ PCR, but this method failed to detect the point mutation. We conclude that our indirect in situ PCR method shows the feasibility of in situ identification of single cells carrying point mutations.     

Haemophilus ducreyi is susceptible to protegrin

Protegrins, potent antimicrobial peptides found in porcine leukocytes, have activity against the sexually transmitted pathogens Neisseria gonorrhoeae, Chlamydia trachomatis, and human immunodeficiency virus type 1. We tested synthetic protegrin 1 (PG-1) for activity against nine isolates of Haemophilus ducreyi, the etiologic agent of chancroid. The test organisms included CIP 542 (the type strain), 35000HP (a human-passaged variant of 35000), 35000HP-RSM2 (an isogenic D-glycero-D-manno-heptosyltransferase mutant of 35000HP), and six clinical isolates. The isolates were epidemiologically unrelated, represented three HindIII ribotypes, and had varying antimicrobial resistance patterns. In bactericidal assays, five isolates were rapidly killed by synthetic PG-1. In radial diffusion assays, all nine isolates were exquisitely sensitive to PG-1. These data highlight the potential of protegrins for development as topical agents to prevent many sexually transmitted diseases, including chancroid.     

Low-dose combination chemotherapy for acute myeloid leukemia in elderly patients: a novel approach

BACKGROUND: The optimal material for carotid patch angioplasty after endarterectomy remains uncertain. This study compares the early outcome and recurrent stenosis rates between saphenous vein (SV) and expanded polytetrafluoroethylene (ePTFE) carotid patch angioplasty. METHODS: The results of 421 consecutive carotid endarterectomies performed over a 72-month period were reviewed. Postoperative complications and restenosis rates, defined as > OR = 60% narrowing measured by color flow duplex, were compared. RESULTS: Patch angioplasty was performed with SV in 287 and with ePTFE in 110 cases. Patients who had undergone primary closure (n = 20) or whose form of closure was unknown (n = 4) were excluded. The mean age of patients and length of follow-up was similar between groups. Women were more likely to be patched with ePTFE than were men (36% versus 23%, P = 0.02). One death occurred in each group (0.3% SV, 0.9% ePTFE, P = 0.47), and four strokes occurred in each group (1.4% SV, 3.6% ePTFE, P = 0.22). Cervical hematomas requiring operative evacuation occurred in five SV closures and in three ePTFE closures (1.7% versus 2.7%, P = 0.69). Vein harvest site complications occurred in 6 patients (2%) who had undergone SV patch angioplasty. Recurrent stenosis occurred in 3 patients with SV closure and in 3 patients with ePTFE closure (1.0% versus 2.7%, P = 0.35). The 60-month restenosis rates by life table analysis were 2.6% +/- 2.1% for SV and 10.7% +/- 7.9% for ePTFE (P = 0.17). CONCLUSIONS: The incidence of postoperative complications is similar with SV or ePTFE patch angioplasty; however, vein harvest site complications are avoided with the use of ePTFE. Recurrent stenosis at 5 years occurs infrequently with either SV or ePTFE.     

Acute hypoxic pulmonary vasoconstriction in man is attenuated by type I angiotensin II receptor blockade

OBJECTIVES: We examined the hypothesis that angiotensin II (ANG II) is a modulator of acute hypoxic pulmonary vasoconstriction (HPV) by looking at the effect of losartan, a selective type 1 ANG II receptor antagonist, on acute HPV in man. METHODS: Ten normal volunteers were studied on two separate days. They either received pre-treatment with losartan 25, 50, 100, 100 mg respectively on four consecutive days or matched placebo. They were then rendered hypoxaemic, by breathing an N2/O2 mixture for 20 min to achieve an SaO2 of 85-90% adjusted for a further 20 min to achieve an SaO2 of 75-80%. Pulsed wave Doppler echocardiography was used to measure mean pulmonary artery pressure (MPAP), cardiac output and hence pulmonary vascular resistance (PVR). RESULTS: Baseline MPAP and PVR (during normoxaemia) were unaffected by losartan pre-treatment compared with placebo. However, losartan significantly reduced MPAP at both levels of hypoxaemia compared with placebo: 14.7 +/- 0.7 vs 19.0 +/- 0.7 mmHg at an SaO2 85-90% (P < 0.01) and 20.0 +/- 0.7 vs 25.7 +/- 0.8 mmHg at an SaO2 75-80% (P < 0.05) respectively. Similarly losartan significantly reduced PVR compared to placebo: 191 +/- 9 vs 246 +/- 10 dyne.s.cm-5 at an SaO2 85-90% (P < 0.005) and 233 +/- 12 vs 293 +/- 18 dyne.s.cm-5 at an SaO2 75-80% (P < 0.05), respectively. Pre-treatment with losartan, however, had no significant effect on systemic vascular resistance although losartan compared to placebo resulted in a significant (P < 0.05) reduction in mean arterial pressure at an SaO2 75-80%: 78 +/- 2 vs 87 +/- 2 mmHg. CONCLUSIONS: Losartan had no effect on baseline pulmonary haemodynamics but significantly attenuated acute hypoxic pulmonary vasoconstriction, suggesting that angiotensin II plays a role in modulating this response in man via its effects on the type 1 angiotensin II receptor.