Homoeologous relationships of rice, wheat and maize chromosomes

A set of cDNA clones, which had previously been mapped onto wheat chromosomes, was genetically mapped onto the chromosomes of rice. The resulting comparative maps make it possible to estimate the degree of linkage conservation between these two species. A number of chromosomal rearrangements, some of which must have involved interchromosomal translocations, differentiate the rice and wheat genomes. However, synteny of a large proportion of the loci appears to be conserved between the two species. The results of this study, combined with those from a recently published comparative map of the rice and maize genomes, suggest that rice, wheat and maize share extensive homoeologies in a number of regions in their genomes. Some chromosomes (e.g. chromosome 4 in rice, chromosomes 2 and 2S in wheat and maize, respectively) may have escaped major rearrangement since the divergence of these species from their last common ancestor. Comparative maps for rice, wheat and maize should make it possible to begin uniting the genetics of these species and allow for transfer of mapping information (including centromere positions) and molecular marker resources (e.g. RFLP probes) between species. In addition, such maps should shed light on the nature of chromosome evolution that accompanied the radiation of grasses in the early stages of plant diversification.

Pitfalls in evaluation of photosensitizing agents: an example with Q-switch II dye

Photosensitizing agents potentiating laser therapy should have limited toxicity, no mutagenicity, stable spectral characteristics, and acceptable solubility when administered in vivo. Q-Switch II dye (QII) has been shown by others to be an effective chromophore for photodynamic therapy at 1051 nm in fibroblast cell culture. The objective of this study was to determine the spectral stability of QII in biological media and then to localize QII after administration in vivo. Spectral evaluation was performed between 250 and 1100 nm. QII dissolved in dimethyl sulfoxide (DMSO) rapidly lost its spectral characteristics, including its 1051-nm peak, when contacting water, minimal essential medium, human serum, organ surfaces, and intracellular fluid. One minute following intramuscular (IM) injection of 0.1 mg QII in 0.2 mL of DMSO, the dose precipitated as a discrete mass which was excised and reconstituted in DMSO. A new spectral pattern was seen, with no absorption between 850 and 1100 nm. Following intravenous (i.v.), (IM), or intraperitoneal (IP) injection, QII was not detected in any organ. Q-Switch II dye is not a suitable chromophore for in vivo photodynamic therapy at 1051 nm. Previous cell culture reports to the contrary did not account for the QII spectral change caused by biological media. Simple rapid assays are described to avoid this pitfall.

Effects of the angiotensin converting enzyme inhibitor enalapril on the long-term progression of left ventricular dilatation in patients with asymptomatic systolic dysfunction. SOLVD (Studies of Left Ventricular Dysfunction) Investigators

BACKGROUND

Patients with heart failure and reduced left ventricular (LV) ejection fraction (EF) manifest progressive LV dilatation, which is prevented by angiotensin converting enzyme (ACE) inhibitors. In patients with asymptomatic LV systolic dysfunction, in whom there is less activation of the renin-angiotensin system, ventricular remodeling might be less rapid and the benefit of ACE inhibitors less discernible.

METHODS AND RESULTS

One hundred eight patients enrolled in the Studies of Left Ventricular Dysfunction (SOLVD) Prevention Trial, with left ventricular ejection fraction < or = 0.35 but without clinical heart failure, underwent radionuclide ventriculograms, and 49 underwent left heart catheterizations. Measurements were made before and after double-blinded randomization to enalapril (2.5 to 20 mg/d) or placebo. Repeated-measures analysis of all time points showed significant differences for change in end-diastolic volume (EDV) between enalapril and placebo groups. Significant difference between the enalapril and placebo groups (P < .05) was present for change in EDV at 1 year within the catheterization study and at a mean of 25 months within the radionuclide study. Radionuclide EDV increased in placebo patients (119 +/- 28 to 124 +/- 33 mL/m2, mean +/- SD) and decreased in enalapril patients (120 +/- 25 to 113 +/- 25 mL/m2). Differences between the two groups were significantly less than previously described in patients with symptomatic heart failure (P < .02), with less increase in LV volumes in the placebo group and less decrease in volumes in the enalapril group.

CONCLUSIONS

Chronic ACE inhibitor treatment slows or reverses LV dilatation in patients with asymptomatic LV systolic dysfunction. Compared with symptomatic patients, asymptomatic patients manifest a slower rate of spontaneous LV dilatation and less reduction in LV volumes by enalapril.

Comparative linkage maps of the rice and maize genomes

Genetic linkage maps have been constructed for the rice and maize genomes on the basis of orthologous loci detected with a common set of cDNA clones. Conserved linkage groups could be identified, which together account for more than two-thirds of both genomes. In some instances, entire chromosomes or chromosome arms are nearly identical with respect to gene order and gene content. The results also reveal that most of the genes (> 72%) duplicated during ancient polyploidization are still present in the maize genome in duplicate copy. The comparative maps of rice and maize provide a basis for interpreting molecular, genetic, and breeding information between these two important species and establish a framework for ultimately connecting the genetics of all grass species.

Effects of long-term enalapril therapy on left ventricular diastolic properties in patients with depressed ejection fraction. SOLVD Investigators

BACKGROUND

The aim of the present study was to analyze the changes in left ventricular diastolic function that occur in patients with chronic severe left ventricular systolic dysfunction in the absence or presence of prolonged therapy with an angiotensin converting enzyme inhibitor.

METHODS AND RESULTS

Left ventricular function data (cineangiography plus Millar, frame-by-frame analysis) and right ventricular volumes (radionuclide angiography) were obtained at baseline and after an average follow-up of 12.4 months in 42 patients with a left ventricular ejection fraction of 35% or less. After baseline measurements, the patients were randomized to placebo (n = 16) or enalapril (10 mg BID, n = 26). In the placebo group, the changes in left ventricular function were characterized by increases in end-diastolic (159 +/- 43 to 170 +/- 44 mL/m2) and end-systolic (119 +/- 38 to 128 +/- 49 mL/m2) volumes accompanied by a downward and rightward shift of the diastolic pressure-volume relation. In contrast, decreases in end-diastolic (166 +/- 43 to 156 +/- 47 mL/m2) and end-systolic (125 +/- 43 to 111 +/- 42 mL/m2) volumes accompanied by a slight upward and leftward shift of the diastolic pressure-volume relation were noted in the enalapril group. These changes in left ventricular volumes were significantly different between groups (both P < .005) but were not attended by changes in left ventricular end-diastolic pressure, in time constant of isovolumic pressure decrease, or in right ventricular volumes. However, the chamber stiffness constant beta decreased from 0.044 +/- 0.027 to 0.032 +/- 0.019 mL-1/m2 in the placebo group, whereas it increased insignificantly in the enalapril group (0.040 +/- 0.028 to 0.041 +/- 0.028 mL-1/m2). These changes in chamber stiffness constant beta between baseline and follow-up were significantly different between placebo and enalapril groups (P < .05). Another index of chamber compliance, delta V/delta P, also confirmed the presence of opposite changes in left ventricular chamber compliance in the placebo group and in the enalapril group. The mean diastolic wall stress increased with placebo but not with enalapril (+51 versus -13 kdyn/cm2; P < .04) whereas left ventricular mass and the indexes of left ventricular sphericity tended to improve in the enalapril group. The changes in plasma levels of norepinephrine, atrial natriuretic peptide, and arginine vasopressin were, however, comparable in both groups.

CONCLUSIONS

The data indicate that in patients with severe systolic left ventricular dysfunction, the progressive left ventricular dilatation was accompanied by a decrease in left ventricular chamber stiffness; enalapril therapy was able to prevent or partially reverse these changes and tended to reduce left ventricular mass and ventricular sphericity. Those changes were suggestive of partial reversal of left ventricular remodeling by enalapril administration.

Fast spin-echo imaging of intracranial neoplasms

Our goal was to compare dual echo fast SE (FSE) T2-weighted MRI of intracranial neoplasms with conventional SE (CSE) images. In phase 1 of the study, CSE and FSE dual echo MR studies of 33 patients with intracranial neoplasms and 26 normal controls were separately interpreted by three neuroradiologists blinded to clinical history to ascertain differences in lesion conspicuity. The CSE and FSE images were read independently, in random order, with at least a 3 week interval between readings. In phase 2 of the study, CSE and FSE sequences were compared side by side by three neuroradiologists independently to evaluate lesion conspicuity and artifacts and to determine whether FSE would be an acceptable replacement for CSE imaging. Lesion detection was equivalent in 111 of 117 interpretations (94.9%). The CSE and FSE sequences were equivalent in detecting lesion-associated abnormalities (hemorrhage, calcium, mass effect, edema, and hydrocephalus) and in characterizing lesion size, margins, and signal intensity. Nonspecific T2 white matter hyperintensities were detected more often with CSE, while susceptibility artifacts were less conspicuous on FSE. Ventricular catheters, postoperative soft tissue and bony changes, and postradiation therapy changes were detected equally well on both sequences. In phase 2 of the study, lesion conspicuity and presence of artifacts were felt to be equivalent with the two sequences. The FSE sequences can serve as a rapid, feasible alternative to conventional CSE sequences for intracranial tumor detection.

Effects of the angiotensin converting enzyme inhibitor enalapril on the long-term progression of left ventricular dysfunction in patients with heart failure. SOLVD Investigators

BACKGROUND

In patients with heart failure, activation of the renin-angiotensin system is common and has been postulated to provide a stimulus for further left ventricular (LV) structural and functional derangement. We tested the hypothesis that chronic administration of the angiotensin converting enzyme (ACE) inhibitor enalapril prevents or reverses LV dilatation and systolic dysfunction among patients with depressed ejection fraction (EF) and symptomatic heart failure.

METHODS AND RESULTS

We examined subsets of patients enrolled in the Treatment Trial of Studies of Left Ventricular Dysfunction (SOLVD). Fifty-six patients with mild to moderate heart failure underwent serial radionuclide ventriculograms, and 16 underwent serial left heart catheterizations, before and after randomization to enalapril (2.5-20 mg/day) or placebo. At 1 year, there were significant treatment differences in LV end-diastolic volume (EDV; p less than 0.01), end-systolic volume (ESV; p less than 0.005), and EF (p less than 0.05). These effects resulted from increases in EDV (mean +/- SD, 136 +/- 27 to 151 +/- 38 ml/m2) and ESV (103 +/- 24 to 116 +/- 24 ml/m2) in the placebo group and decreases in EDV (140 +/- 44 to 127 +/- 37 ml/m2) and ESV (106 +/- 42 to 93 +/- 37 ml/m2) in the enalapril group. Mean LVEF increased in enalapril patients from 0.25 +/- 0.07 to 0.29 +/- 0.08 (p less than 0.01). There was a significant treatment difference in LV end-diastolic pressure at 1 year (p less than 0.05), with changes paralleling those of EDV. The time constant of LV relaxation changed only in the placebo group (p less than 0.01 versus enalapril), increasing from 59.2 +/- 8.0 to 67.8 +/- 7.2 msec. Serial radionuclide studies over a period of 33 months showed increases in LV volumes only in the placebo group. Two weeks after withdrawal of enalapril, EDV and ESV increased to baseline levels but not to the higher levels observed with placebo.

CONCLUSIONS

In patients with heart failure and reduced LVEF, chronic ACE inhibition with enalapril prevents progressive LV dilatation and systolic dysfunction (increased ESV). These effects probably result from a combination of altered remodeling and sustained reduction in preload and afterload.

Electrogenicity of the Na-K-ATPase pump in bullfrog cornea epithelium

The effect of changing the K concentration in the aqueous solution was studied in the frog cornea. In general, when the K concentration was increased from 4 to 20 or 79 mM, the transepithelial PD and resistance decreased. If K was decreased from 79 to 4, 20 to 4, or 4 to 0 mM, or any other combination, the PD and resistance increased. These are normal PD responses. If after a K-free period of more than 5-10 min the K was increased to 4 mM, the PD increased, an anomalous PD response. If K was increased from 0 to 20 mM, there was an initial PD increase (anomalous response) followed by a PD decrease (normal response). If K was increased from 0 to 79 mM the PD decreased, normal response only. The resistance decreased with every increase in K concentration. Anomalous responses were abolished in Na-free solutions and in the presence of both 10(-3) M ouabain and 10(-4) M vanadate in the aqueous solution. We interpret the results on the basis of two pathways, a simple K-conductive pathway and an electrogenic Na-K-ATPase pump pathway with more Na's than K's per cycle. The normal or anomalous PD responses to changes in aqueous K concentration depend on the relative resistance of the two pathways.

Chemotherapy for pulmonary disease due to Mycobacterium kansasii: efficacies of some individual drugs

An evaluation of chemotherapy was made for 256 patients with pulmonary infection due to Mycobacterium kansasii. Studies of in vitro resistance of M. kansasii and Mycobacterium tuberculosis to various drugs revealed important differences between the two species that should be considered when planning chemotherapy. Partial or no in vitro resistance to 1 microgram of isoniazid/ml did not adversely affect the time required for conversion of sputum from positive to negative, whereas complete resistance to isoniazid had a statistically significant (P less than 0.001) adverse effect. All of the 115 patients who received treatment that included rifampin (initial and retreatment) had sputum conversion within four months. However, for regimens that did not include rifampin, 127 (90%) of 141 patients had conversion within four months (P less than 0.01). After completion of chemotherapy that included rifampin, there were no relapses among 64 patients, but after therapy without rifampin, four (7%) of 59 patients relapsed. The greater efficacy of the regimens that included rifampin may be due at least partially to the fact that more drugs were administered than in regimens that did not include rifampin. The use of p-aminosalicylic acid seems unwarranted in the treatment of disease due to M. kansasii. Since rifampin may be the most potent drug for treatment of this disease, the recommended combinations for initial treatment are (l) rifampin, streptomycin, isoniazid, and ethambutol, or (2) rifampin and two other drugs to which the organism is sensitive.

L-Asparagainases from Citrobacter freundii

Three enzymes which catalyze the hydrolysis of L-asparagine have been identified in extracts of Citrobacter freundii. One of these (asparaginase-glutaminase (EC 3.5.1.1) also shows substantial glutaminase activity. This enzyme is extremely labile, is sensitive to inactivation by p-chloromercuribenzoate, and is not protected by dithiothreitol. A second enzyme (asparaginase B) is also sensitive to mercurials but is protected from inactivation by dithiothreitol. This enzyme has a relatively low affinity for L-asparagine (Km = 1.7-10(-3) M). The third enzyme (asparaginase A) is insensitive to inactivation by mercurials, is stable upon long term storage and has a relatively high affinity for L-asparagine (Km = 2.9-10(-5) M). This enzyme has been purified to homogeneity and has a molecular weight of approx. 140 000; the subunit weight being approx. 33 000. The C. freundii asparaginase A produced significant increases in the survival time of C3H/HE mice carrying the 6C3HED lymphoma tumor.