Quantification of myocardial fibrosis using noninvasive T2-mapping magnetic resonance imaging: Preclinical models of aging and pressure overload

Noninvasive imaging of cardiac fibrosis is important for early diagnosis and intervention in chronic heart diseases. Here, we investigated whether noninvasive, contrast agent-free MRI T₂-mapping can quantify myocardial fibrosis in preclinical models of aging and pressure overload. Myocardial fibrosis and remodeling were analyzed in two animal models: (i) aging (15-month-old male CF-1 mice vs. young 6- to 8-week-old mice), and (ii) pressure overload (PO; by transverse aortic constriction in 4- to 5-month-old male C57BL/6 mice vs. sham-operated for 14 days). In vivo T₂-mapping was performed by acquiring data during the isovolumic and early diastolic phases, with a modified respiratory and ECG-triggered multiecho TurboRARE sequence on a 7-T MRI. Cine MRI provided cardiac morphology and function. A quantitative segmentation method was developed to analyze the in vivo T₂-maps of hearts at midventricle, apex, and basal regions. The cardiac fibrosis area was analyzed ex vivo by picro sirius red (PSR) staining. Both aged and pressure-overloaded hearts developed significant myocardial contractile dysfunction, cardiac hypertrophy, and interstitial fibrosis. The aged mice had two phenotypes, fibrotic and mild-fibrotic. Notably, the aged fibrotic subgroup and the PO mice showed a marked decrease in T₂ relaxation times (25.3 ± 0.6 in aged vs. 29.9 ± 0.7 ms in young mice, p = 0.002; and 24.3 ± 1.7 in PO vs. 28.7 ± 0.7 ms in shams, p = 0.05). However, no significant difference in T₂ was detected between the aged mild-fibrotic subgroup and the young mice. Accordingly, an inverse correlation between myocardial fibrosis percentage (FP) and T₂ relaxation time was derived (R² = 0.98): T₂ (ms) = 30.45 – 1.05 × FP. Thus, these results demonstrate a statistical agreement between T₂-map–quantified fibrosis and PSR staining in two different clinically relevant animal models. In conclusion, T₂-mapping MRI is a promising noninvasive contrast agent-free quantitative technique to characterize myocardial fibrosis.     

Cross protection against fowl typhoid immunisation trials and humoral immune response

Chicks were immunised with different vaccines intramuscularly at the age of eight weeks and challenged twenty one days later with 10 LD50 dose of virulent $\text{S. gallinarum}$ V intramuscularly. The percentage of absolute survivors were taken as the criterion to assess the potency of the vaccines. To assess the humoral response, sequential levels of antibodies by different tests were assessed before and after vaccination and after challenge.Live vaccines with adjuvants proved to be the best followed by live vaccines. Cross protection could be induced. Assessment of sequential levels of humoral immune response revealed involvement of agglutinins and bactericidal antibodies but such an involvement appears to be not essential for protection.     

Replication-independent expression of genome components and capsid protein of brome mosaic virus in planta: a functional role for viral replicase in RNA packaging

To begin elucidation of the relationship between Brome mosaic virus (BMV) replication and encapsidation, we used a T-DNA-based Agrobacterium-mediated transient expression (agroinfiltration) system in Nicotiana benthamiana leaves to express either individual or desired pairs of the three genomic RNAs. The packaging competence of these RNAs into virions formed by the transiently expressed coat protein (CP) was analyzed. We found that in the absence of a functional replicase, assembled virions contained non-replicating viral RNAs (RNA1 or RNA2 or RNA3 or RNA1 + RNA3 or RNA2 + RNA3) as well as cellular RNAs. By contrast, virions assembled in the presence of a functional replicase contained only viral RNAs. To further elucidate the specificity exhibited by the functional viral replicase in RNA packaging, replication-defective RNA1 and RNA2 were constructed by deleting the 3' tRNA-like structure (3' TLS). Co-expression of TLS-less RNA1 and RNA2 with wt RNA3 resulted in efficient synthesis of subgenomic RNA4. Virions recovered from leaves co-expressing TLS-less RNA1 and RNA2 and either CP mRNA or wt RNA3 exclusively contained viral RNAs. These results demonstrated that packaging of BMV genomic RNAs is not replication dependent whereas expression of a functional viral replicase plays an active role in increasing specificity of RNA packaging.     

In-vitro susceptibility of cefoperazone-susceptible and -resistant gram-negative rods to cefoperazone plus sulbactam,other beta-lactams,aminoglycosides and quinolone

Summary We compared thein-vitro activity of cefoperazone-sulbactam (2 : 1), other -lactams, aminoglycosides and ciprofloxacin against cefoperazone-susceptible and -resistant nosocomial gram-negative bacilli. Resistant isolates includingPseudomonas aeruginosa were susceptible to cefoperazone-sulbactam; the susceptible isolates had modestly increased susceptibility to the combination. Sulbactam, by itself, was poorly active. Among others tested, ciprofloxacin and imipenem were the most active. No inoculum effect was seen with cefoperazone-sulbactam and this drug combination had a prolonged post-antibiotic effect. Cefoperazone-sulbactam is an attractive candidate for evaluation in the treatment of nosocomial infections due to aerobic gram-negative bacilli.

---

In-vitro-Empfindlichkeit cefoperazon-sensibler und -resistenter gramnegativer Stäbchen gegenüber Cefoperazon plus Sulbactam, anderen -Laktamen, Aminoglykosiden und Chinolon

Zusammenfassung Wir führten Vergleichsuntersuchungen zurIn-vitro-Aktivität von Cefoperazon-Sulbactam (2 : 1), anderen -Laktamen, Aminoglykosiden und Ciprofloxacin gegen cefoperazon-empfindliche und -resistente nosokomiale Isolate gramnegativer Bazillen durch. Resistente Isolate einschließlichPseudomonas aeruginosa waren empfindlich gegenüber Cefoperazon-Sulbactam; empfindliche Isolate sprachen auf die Kombination etwas besser an. Sulbactam allein wies nur geringe Aktivität auf. Unter den übrigen geprüften Substanzen waren Ciprofloxacin und Imipenem am wirksamsten. Mit Cefoperazon-Sulbactam war kein Inoculum-Effekt festzustellen. Die Kombination hatte einen anhaltenden postantibiotischen Effekt. Cefoperazon-Sulbactam ist eine interessante Substanzkombination, die in der Therapie nosokomialer Infektionen durch aerobe gramnegative Bazillen erprobt werden sollte.

---

---

This study was presented at the 89th Annual Meeting of the American Society for Microbiology held in New Orleans, Louisiana during May 14–18, 1989.     

Glial cell-induced endothelial morphogenesis is inhibited by interfering with extracellular signal-regulated kinase signaling.

PURPOSE: Tumor vasculature provides the infrastructure by which malignant tissue can be nourished; therefore, targeting angiogenesis may be an effective means of treating cancer. We showed previously that SNB19 glioblastoma cells modulate bovine retinal endothelial cells in cocultures to form capillary-like network structures, that matrix metalloproteinase-9 (MMP-9) expression is critical for endothelial morphogenesis, and that MMP-9 expression in glioblastoma cells is regulated by extracellular signal-regulated kinase-1 (ERK-1). In the present study, we investigated whether interfering with the activation of this mitogen-activated protein (MAP) kinase would repress MMP-9 synthesis and inhibit capillary formation. EXPERIMENTAL DESIGN: Cocultures of bovine retinal endothelial and SNB19 cells were analyzed for MMP-9 secretion, and phospho- and total ERK levels. These cocultures were treated with PD98059, a specific inhibitor of MAP/ERK kinase 1, or transfected with dominant-negative ERK-1 mutant containing expression vector. Alterations in capillary-like structure formation, and actin cytoskeleton and secretion of vascular endothelial growth factor (VEGF), MMP-9, and tissue inhibitor of metalloproteinase-1 were determined by immunofluorescence, gelatin zymography, and Western blotting. RESULTS: We found that inhibition of the ERK-1/2 pathway with PD98059 abrogated glial cell-mediated capillary formation by the endothelial cells and reduced the levels of MMP-9 in the coculture. Strikingly, the abrogation of MAP kinase signaling by a dominant-negative ERK-1 mutant inhibited glial-induced capillary network formation by reducing VEGF levels and MMP-9 activity and increasing the levels of tissue inhibitor of metalloproteinase-1. Inhibition of ERK activity also disrupted the formation of the actin cytoskeleton, a prerequisite for endothelial cell migration. CONCLUSION: The mechanism underlying activation of ERK is involved in reorganization of the actin cytoskeleton, and induction of VEGF and MMP-9, thereby stimulating endothelial cell morphogenesis. These studies clearly provide experimental evidence that ERK inhibition diminishes glial-induced endothelial-cell morphogenesis; therefore, interfering with ERK signaling may be a viable approach to target angiogenesis.     

A patient-specific quality assurance study on absolute dose verification using ionization chambers of different volumes in RapidArc treatments

The recalculation of 1 fraction from a patient treatment plan on a phantom and subsequent measurements have become the norms for measurement-based verification, which combines the quality assurance recommendations that deal with the treatment planning system and the beam delivery system. This type of evaluation has prompted attention to measurement equipment and techniques. Ionization chambers are considered the gold standard because of their precision, availability, and relative ease of use. This study evaluates and compares 5 different ionization chambers: phantom combinations for verification in routine patient-specific quality assurance of RapidArc treatments. Fifteen different RapidArc plans conforming to the clinical standards were selected for the study. Verification plans were then created for each treatment plan with different chamber-phantom combinations scanned by computed tomography. This includes Medtec intensity modulated radiation therapy (IMRT) phantom with micro-ionization chamber (0.007 cm³) and pinpoint chamber (0.015 cm³), PTW-Octavius phantom with semiflex chamber (0.125 cm³) and 2D array (0.125 cm³), and indigenously made Circular wax phantom with 0.6 cm³ chamber. The measured isocenter absolute dose was compared with the treatment planning system (TPS) plan. The micro-ionization chamber shows more deviations when compared with semiflex and 0.6 cm³ with a maximum variation of ?4.76%, ?1.49%, and 2.23% for micro-ionization, semiflex, and farmer chambers, respectively. The positive variations indicate that the chamber with larger volume overestimates. Farmer chamber shows higher deviation when compared with 0.125 cm³. In general the deviation was found to be <1% with the semiflex and farmer chambers. A maximum variation of 2% was observed for the 0.007 cm³ ionization chamber, except in a few cases. Pinpoint chamber underestimates the calculated isocenter dose by a maximum of 4.8%. Absolute dose measurements using the semiflex ionization chamber with intermediate volume (0.125 cm³) shows good agreement with the TPS calculated among the detectors used in this study. Positioning is very important when using smaller volume chambers because they are more sensitive to geometrical errors within the treatment fields. It is also suggested to average the dose over the sensitive volume for larger-volume chambers. The ionization chamber-phantom combinations used in this study can be used interchangeably for routine RapidArc patient-specific quality assurance with a satisfactory accuracy for clinical practice.