Chromosomal rearrangement generating a composite gene for a developmental transcription factor.

Differential gene expression in the mother cell chamber of sporulating cells of Bacillus subtilis is determined in part by an RNA polymerase sigma factor called sigma K (or sigma 27). The sigma K factor was assigned as the product of the sporulation gene spoIVCB on the basis of the partial aminoterminal amino acid sequence of the purified protein. The spoIVCB gene is now shown to be a truncated gene capable of specifying only the amino terminal half of sigma K. The carboxyl terminal half is specified by another sporulation gene, spoIIIC, to which spoIVCB becomes joined inframe at an intermediate stage of sporulation by site-specific recombination within a 5-base pair repeated sequence. Juxtaposition of spoIVCB and spoIIIC need not be reversible in that the mother cell and its chromosome are discarded at the end of the developmental cycle. The rearrangement of chromosomal DNA could account for the presence of sigma K selectively in the mother cell and may be a precedent for the generation of cell type-specific regulatory proteins in other developmental systems where cells undergo terminal differentiation.

Switch protein alters specificity of RNA polymerase containing a compartment-specific sigma factor.

During sporulation in Bacillus subtilis, expression of developmental genes spoIVCB and cotD is induced in the mother cell compartment of the sporangium at morphological stages IV and V, respectively. A 27-kilodalton RNA polymerase sigma factor called sigma K (or sigma 27) has been found that causes weak transcription of spoIVCB and strong transcription of cotD. A 14-kD protein was also discovered that changes the specificity of sigma K-containing RNA polymerase, greatly stimulating spoIVCB transcription and markedly repressing cotD transcription. Both sigma K and the 14-kD protein are products of genes known to be required for expression of specific genes in the mother cell. Thus, sigma K directs gene expression in the mother cell and it is proposed that inactivation or sequestering of the 14-kD protein switches the temporal pattern of gene expression during the transition from stages IV to V of development.

RPS2 of Arabidopsis thaliana: a leucine-rich repeat class of plant disease resistance genes.

Plant disease resistance genes function is highly specific pathogen recognition pathways. PRS2 is a resistance gene of Arabidopsis thaliana that confers resistance against Pseudomonas syringae bacteria that express avirulence gene avrRpt2. RPS2 was isolated by the use of a positional cloning strategy. The derived amino acid sequence of RPS2 contains leucine-rich repeat, membrane-spanning, leucine zipper, and P loop domains. The function of the RPS2 gene product in defense signal transduction is postulated to involve nucleotide triphosphate binding and protein-protein interactions and may also involve the reception of an elicitor produced by the avirulent pathogen.

Compartmentalized gene expression during sporulation in Bacillus subtilis.

Two important features of endospore development in Bacillus subtilis--the compartmentalization of mother cell gene expression and the coordination of mother cell gene expression with forespore development--are governed by the highly regulated expression of the sigK gene, which encodes the mother cell-specific RNA polymerase sigma factor sigma K. Compartmentalized expression of sigK is associated both with a chromosomal DNA rearrangement and with the restriction of sigK transcription to the mother cell. A third mode of sigK regulation, which occurs at the level of activation of the sigK gene product by proteolytic processing, serves to couple gene expression between the mother cell and forespore compartments of the developing sporangium.

A useful weed put to work: genetic analysis of disease resistance in Arabidopsis thaliana.

Plant resistance to disease caused by phytopathogenic organisms is often triggered by the ability of the plant to specifically recognize the invading pathogen. One of the most fascinating areas in plant biology research focusses on understanding the mechanisms governing this process. Several recent breakthroughs in this area have come from the genetic analyses of disease resistance in Arabidopsis thaliana.

The Pseudomonas syringae avrRpt2 gene product promotes pathogen virulence from inside plant cells.

Several bacterial avr genes have been shown to contribute to virulence on susceptible plants lacking the corresponding resistance (R) gene. The mechanisms by which avr genes promote parasitism and disease, however, are not well understood. We investigated the role of the Pseudomonas syringae pv. tomato avrRpt2 gene in pathogenesis by studying the interaction of P. syringae pv. tomato strain PstDC3000 expressing avrRpt2 with several Arabidopsis thaliana lines lacking the corresponding R gene, RPS2. We found that PstDC3000 expressing avrRpt2 grew to significantly higher levels and often resulted in the formation of more severe disease symptoms in ecotype No-0 plants carrying a mutant RPS2 allele, as well as in two Col-0 mutant lines, cpr5 rps2 and coil rps2, that exhibit enhanced resistance. We also generated transgenic A. thaliana lines expressing avrRpt2 and demonstrated, by using several different assays, that expression of avrRpt2 within the plant also promotes virulence of PstDC3000. Thus, AvrRpt2 appears to promote pathogen virulence from within the plant cell.

Identification, characterization and comparative analysis of a novel chorismate mutase gene in Arabidopsis thaliana.

Phenylalanine, tyrosine, and tryptophan have a dual biosynthetic role in plants; they are required for protein synthesis and are also precursors to a number of aromatic secondary metabolites critical to normal development and stress responses. Whereas much has been learned in recent years about the genetic control of tryptophan biosynthesis in Arabidopsis and other plants, relatively little is known about the genetic regulation of phenylalanine and tyrosine synthesis. We have isolated, characterized and determined the expression of Arabidopsis thaliana genes encoding chorismate mutase, the enzyme catalyzing the first committed step in phenylalanine and tyrosine synthesis. Three independent Arabidopsis chorismate mutase cDNAs were isolated by functional complementation of a Saccharomyces cerevisiae mutation. Two of these cDNAs have been reported independently (Eberhard et al., 1993. FEBS 334, 233-236; Eberhard et al., 1996. Plant J. 10, 815-821), but the third (designated CM-3) represents a novel gene. The different organ-specific expression patterns of these cDNAs, their regulation in response to pathogen infiltration, as well as the different enzymatic characteristics of the proteins they encode are also described. Together, these data suggest that each isoform may play a distinct physiological role in coordinating chorismate mutase activity with developmental and environmental signals.

Combined first-pass and equilibrium radionuclide ventriculography and comparison with left ventricular/right ventricular stroke count ratio in mitral and aortic regurgitation.

Effective and total left ventricular (LV) stroke volume were assessed in 31 patients with verified aortic or mitral regurgitation, or both, and in 22 patients with normal valvular function using combined first-pass and equilibrium radionuclide ventriculography. The difference between these 2 volumes as a fraction of LV stroke volume was taken as the radionuclide regurgitant fraction. The results were compared with the LV/right ventricular (RV) stroke count ratio and with the angiographic regurgitant fraction according to the method of Sandler and Dodge. Radionuclide regurgitant fraction derived from 2 determinations with a time interval of 1 week showed good reproducibility (n = 15, r = 0.96, SEE = 9.1). Sensitivity was 100% for radionuclide regurgitant fraction and 87% for LV/RV stroke count ratio at equal specificity (100%). Radionuclide regurgitant fraction was more sensitive, especially in severely ill patients, in whom additional RV volume overload led to false-low or false-negative ratios. Angiographic and radionuclide regurgitant fraction showed linear correlation (r = 0.79, p less than 0.001). In contrast, because 5 patients had RV volume overload, only a weak correlation could be noticed between angiography and LV/RV stroke count ratio (r = 0.47, p less than 0.05). Excluding these patients, correlation substantially improved (r = 0.74, p less than 0.001). The combination of first-pass and equilibrium radionuclide ventriculography is a sensitive, specific and well reproducible method for the evaluation of mitral and aortic regurgitation.(ABSTRACT TRUNCATED AT 250 WORDS)

Assessment of cardiac adrenergic supply in mitral valve prolapse using m-[123I]iodobenzylguanidine scintigraphy.

Presynaptic as well as postsynaptic adrenergic regulation abnormalities are reported in symptomatic patients with mitral valve prolapse. This study was undertaken to evaluate presynaptic sympathetic supply by m-[123I]iodobenzylguanidine scintigraphy in 17 preselected patients with mitral valve prolapse and symptoms suggestive of hyperadrenergic dysautonomia as compared to normal scintigraphic findings. Mitral valve prolapse was echocardiographically proven within the left parasternal long axis view. Percentual activity of m-[123I]iodobenzylguanidine in 33 sectors of all oblique slices along the short axis was calculated relative to the maximal uptake, set at 100%. In general, no significant differences of mean values of sectoral quantitative uptake of m-[123I]iodobenzylguanidine were detectable between patients and the control group. Only in two sectors of the basal anterolateral region P values < 0.01 were present. Thus, using m-[123I]iodobenzylguanidine scintigraphy as marker of cardiac adrenergic supply, no evidence of altered presynaptic hyperadrenergic supply was present in patients with mitral valve prolapse. These findings suggest postsynaptic regulation abnormalities to be preponderant in this condition.

Assessment of spatial and temporal velocity profiles distal of normally functioning Björk-Shiley prosthesis by the Doppler method.

By Doppler echocardiography, the performance of heart valve prostheses is assessed with the aid of maximal transprosthetic velocities, which, however, may not be representative for the full spatial velocity profile in the vicinity of mechanical valve substitutes due to flow separation by the open occluder. The purpose of this study was to determine characteristics of velocity profiles downstream of a normally functioning Björk-Shiley prosthesis. In a pulsatile flow apparatus, different flow rates of 6.3 and 8.4 l/min were delivered. Using a spatially and temporally resolving ultrasonic Doppler method, velocity profiles 20 and 30 mm distal from the prosthesis were registered and displayed in a three-dimensional grid. The spatial velocity profile was found to deviate substantially from a flat profile at these transducer positions at the two flow conditions. Distal to the minor orifice, velocities measured only 70 and 80% of those downstream of the major orifice. In between, a region of relatively slow moving flow was present. The shape of the profiles remained essentially unchanged during acceleration and deceleration of flow. Thus, spatially resolved velocity profiles downstream of mechanical prostheses can be registered by an ultrasonic Doppler device. These findings may be useful for the detection of beginning malfunction both in the experimental and the clinical setting.

[Advances in cerebral angiography (author's transl)]. / Fortschritte in der zerebralen Angiographie.

During recent years, catheter angiography of the cerebral vessels has tended to displace direct puncture of the carotid arteries. The method has significant advantages for the radiologist and the patient. A number of procedures are described which make this examination more easily performed, increase its diagnostic value and, most important, render it safer for the patient. Changes in catheter technique, in the radiographic apparatus and in the scope of the method are discussed.

[Magnetic resonance tomography of the postoperative lumbar spine. A comparison of the MR versus CT images in recurrent intervertebral disk prolapse]. / Kernspintomographie der operierten Lendenwirbelsäule. Bildvergleich MR versus CT bei Bandscheibenrezidiven.

In the present study, 40 patients who had undergone disc surgery were examined by high resolution CT and MR for possible recurrence of the disc prolapse and the results are compared. It appears that high resolution spinal MR, using its various tissue parameters provides no new insights into possible recurrence of a disc prolapse. As is the case with CT, the investigator must also evaluate other morphological and clinical factors. In spite of this, MR can be useful in the investigation of abnormal spines.

Analysis of adhesion molecules in myocardial biopsies of cardiac allografts and coronary artery disease with CABG.

Interactions of leukocytes with vascular endothelium are important components of inflammation tissue reactions and have been implicated in cardiac transplant rejection and demonstrated to be mediated by cell adhesion molecules (CAM's). The expression of ICAM-1, VCAM-1 and E-selectin in human myocardium is variable and little is known about the expression of LFA-1 and Mac-1 during allograft rejection. This study investigated these CAM's in myocardial biopsies of transplanted hearts (HTX) and of coronary artery disease eligible for coronary artery bypass grafting (CABG) as non-inflammatory controls and explicitly examines vascular endothelium, cardiomyocytes and infiltrating cells. Immunohistochemistry was performed using the APAAP-method and directing specific mouse anti-human monoclonal antibodies against ICAM-1 (CD54), VCAM-1 (CD106), E-selectin (CD62E), alpha-LFA-1 (CD11a), alpha-Mac-1 (CD11b), alpha-p150/95 (CD11c) and the beta2-integrin chain (CD18). CD18, LFA-1 (CD11a), Mac-1 (CD11b) and p150/95 (CD11c) were markedly expressed on infiltrating immunocytes in HTX compared to CABG where no expression of beta2-integrins was observed. Cardiac allografts demonstrated a strong expression of ICAM-1 on vascular endothelium and on infiltrating cells. ICAM-1 was not detected on cardiomyocytes. In CABG a weak expression of ICAM-1 was observed on endothelial cells but not on myocytes. VCAM-1 was expressed on vascular endothelium and perivascular infiltrating cells in HTX but not in CABG. VCAM-1 was not found to be expressed on myocytes. There was no evidence for the presence of E-selectin in any of our biopsy specimens. Our study shows that the study of cell adhesion molecules adds to the pathophysiological understanding of inflammation after transplantation in cardiac disease. This offers a potential for the development of diagnostic tools and new therapeutic strategies.

Lethal and sublethal effects of bendiocarb, halofenozide, and imidacloprid on Harpalus pennsylvanicus (Coleoptera: Carabidae) following different modes of exposure in turfgrass.

Routes by which nontarget predatory insects can be exposed to turfgrass pesticides include topical, residual, and dietary exposure. We used each of these routes to evaluate potential lethal or sublethal effects of two novel turfgrass insecticides, imidacloprid and halofenozide, and a carbamate, bendiocarb, on survival, behavior, and fecundity of the ground beetle Harpalus pennsylvanicus DeGeer. Field-collected carabids were exposed to direct spray applications in turf plots, fed food contaminated by such applications, or exposed to irrigated or nonirrigated residues on turf cores. Halofenozide caused no apparent acute, adverse effects through topical, residual, or dietary exposure. Moreover, the viability of eggs laid by females fed halofenozide-treated food once, or continuously for 30 d, was not reduced. In contrast, topical or dietary exposure of carabids to bendiocarb inevitably was lethal. Exposure to imidacloprid by those routes caused high incidence of sublethal, neurotoxic effects including paralysis, impaired walking, and excessive grooming. Intoxicated beetles usually recovered within a few days in the laboratory, but in the field, they were shown to be highly vulnerable to predation by ants. One-time intoxication by imidacloprid did not reduce females' fecundity or viability of eggs. There was no apparent behavioral avoidance of insecticide residues, or of insecticide-treated food. Carabids exposed to dry residues on turfgrass cores suffered high mortality from bendiocarb, and some intoxication from imidacloprid, but these effects were greatly reduced by posttreatment irrigation. Implications for predicting hazards of insecticides to beneficial invertebrates in turfgrass are discussed.

Use of Arabidopsis thaliana and Pseudomonas syringae in the Study of Plant Disease Resistance and Tolerance.

The interaction between Arabidopsis thaliana and the bacterium Pseudomonas syringae is being developed as a model experimental system for plant pathology research. Race-specific ("gene-for-gene") resistance has been demonstrated for this interaction, and pathogen genes that determine avirulence have been isolated and characterized. Because certain lines of both Arabidopsis and soybean are resistant to bacteria carrying the avirulence genes avrRpt2 and avrB, extremely similar pathogen recognition mechanisms are apparently present in these two plant species. Isogenic bacterial strains that differ by the presence of single avirulence genes are being used to analyze plant resistance. Plant resistance genes have been identified in crosses between resistant and susceptible lines. The extensive map-based cloning tools available in Arabidopsis are being used to isolate these resistance genes. In a related project, ethylene-insensitive Arabidopsis mutants are being used to examine the role of ethylene in disease development. Ethylene apparently mediates symptom formation in susceptible plants and is not required for resistance, suggesting possible strategies for enhancement of disease tolerance in crops.

[Percutaneous transluminal coronary angioplasty in patients with clearly restricted left ventricular pump function]. / Perkutane transluminale Koronarangioplastie bei Patienten mit deutlich eingeschränkter linksventrikulärer Pumpfunktion.

Among nearly 2000 consecutive PTCA-patients 42 (36 male, six female; mean age 60 +/- 11 years) had ejection fractions < or = 35% (mean 30 +/- 5%). 34 patients suffered from unstable and eight from stable angina. All had previous myocardial infarction and of these 23 had recent myocardial infarction. Four patients had prior coronary bypass surgery and one had undergone aneurysmectomy. 31 of 42 (= 74%) patients had multiple vessel disease (stenoses > 50%). Successful procedure was achieved in 35 of 42 patients (= 83%). The lesion-related success rate of PTCA was 89%, of recanalization 60%. Six procedures were multiple vessel PT-CA. Major complications occurred in two of 42 patients (one myocardial infarction, one emergency bypass operation). The in-hospital mortality was 2.4%. Follow-up angiography was performed in 22 patients and showed restenoses in nine cases. All patients underwent repeat coronary angioplasty, of these one patient had postprocedural myocardial infarction. The ejection fraction had meanwhile significantly improved from 29 +/- 5% to 36 +/- 7%. Clinical follow-up after 18 +/- 14 months (two to 53 months) was available in 39 of 40 patients, who were discharged from hospital without major complications. 29 patients were free of angina or anginal class II, one had a late cardiac transplant. Five patients had died of cardiac and one of noncardiac causes. Thus, PTCA in patients with severely depressed ventricular function shows acceptable acute results, which are comparable to those of routine angioplasty, continued symptomatic improvement can be achieved. However, the late outcome is significantly worse than in patients with normal left ventricular function.

[Traumatological risk in ambulatory cardiological rehabilitation]. / Traumatologische Risiken der ambulanten kardiologischen Rehabilitation.

BACKGROUND: In Israel in 1956 Gottheiner introduced outpatient rehabilitation programs in patients who had survived a myocardial infarction. In Germany one decade later these WHO phase III activities were established as well. At present any patient with cardiovascular disease is included unless suffering from acute illnesses or presenting with symptoms at rest. Gymnastics, stretching and the "historic" volleyball are completed by jogging, soccer, basketball and anaerobic exercise. Thus, a notable trauma rate would be expected especially in the elderly and those who are on anticoagulation. METHODS: A retrospective analysis evaluated questionnaires of 903 patients in 116 outpatient coronary care groups covering approximately equal to 270,000 patient exercise hours. RESULTS: 101 of 123 injuries (approximately equal to 1/2 200 patient exercise hours) occurred during games the majority of which having been distortions (53.7%), hematomas, or bruises (15.4%). Severe traumas included bone fractures (11.4%) and ruptured muscles, tendons, or ligaments (12.2%). One patient lost the sight of one eye due to a broken spectacle frame. Patients who had felt exercise as too exhausting (p < 0.001) or complained of cardiovascular symptoms (p < 0.01) showed a significantly elevated trauma rate. CONCLUSIONS: Thus, in outpatient cardiac rehabilitation the trauma rate is within the range of healthy sports men. To prevent injuries sports should be limited to the patient's level of activity. Improved skills in techniques and strategies as well as unbreakable glasses are recommended.