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Biomedical subjects

R Jenni

Publications and source records attributed to R Jenni.

At least 19 recordsLinked to original sources
PubMed1998

Sequence of the putative alanine racemase operon in Staphylococcus aureus: insertional interruption of this operon reduces D-alanine substitution of lipoteichoic acid and autolysis.

A gene cluster comprising the alanine racemase gene alr was identified 5' to the sigB operon in Staphylococcus aureus. It is flanked upstream by four ORFs of which one shows similarity to the dpj gene of Escherichia coli, and downstream by two ORFs of which the last shows similarity to the E. coli pemK gene. Preliminary data suggest that the seven ORFs orf1-orf2-orf3-dpj-alr-orf6-pemK may form an operon. Disruption of the proposed operon by insertional mutagenesis leads to a drastic loss in the d-alanine (d-Ala) substitution of lipoteichoic acid and to delayed autolysis, without affecting the d-Ala substitution of the wall teichoic acid.

Alanine↗
PubMed1998

Prognosis of medically treated patients referred for cardiac transplantation.

OBJECTIVES: To assess prognosis and factors influencing survival of transplant candidates in whom continued medial therapy was recommended in comparison to that of immediately listed patients. METHODS: Retrospective analysis of clinical, echocardiographic and hemodynamic data as related to survival or listing for transplantation of medically treated transplant candidates. PATIENTS: 160 patients considered 'too well' for cardiac transplantation and 133 patients immediately listed for transplantation. RESULTS: Forty-one of the medically treated patients deteriorated clinically and were listed after 10.7+/-12.3 months after initial evaluation. Mid-term prognosis (2 years) of patients never listed was comparable to that of immediately listed patients (74% vs. 70%) but long-term prognosis (5 years) was worse (41% vs. 54%, p<0.001). Cardiothoracic ratio and pulmonary capillary wedge pressure were independent predictors of survival (multivariate analysis) in patients whose NYHA class and physical working capacity improved and cardiothoracic ratio decreased significantly after adjustment of medical therapy. CONCLUSIONS: Mid-term prognosis of selected patients considered 'too well' for transplantation is comparable to patients immediately listed. Lower left ventricular filling pressures, smaller hearts on chest X-ray on initial evaluation, and improvement of symptoms during follow up may identify a subgroup of patients who do well on optimized therapy.

Actuarial Analysis↗
PubMed1998

Position control of intravascular Doppler guidewire: concept of a tracking indicator and its clinical implications.

Intracoronary Doppler ultrasound guidewires (DGW) utilize a wide ultrasound beam combined with a measurement of the spectral peak velocity to estimate the spatial peak velocity within a blood vessel. However, the spectral peak velocity may underestimate the true spatial peak velocity if the DGW is not properly positioned. The purpose of this study was to find a Doppler-derived parameter that would aid in the optimal positioning of the DGW within the vessel lumen. We studied the relationship between the time-averaged, spectral-peak velocity (APV) and the normalized first Doppler moment (M1/M0) to develop a DGW position indicator and demonstrate its clinical utility. In vitro, heparinized, human whole blood with a hematocrit of 45% was directed from a reservoir via a roller pump into four serially connected straight silicone tubes of known diameter (2.5, 3.0, 3.5, 4.0 mm). A DGW was inserted into the tubes where simultaneous APV and M1/M0 measurements were obtained for flow rates ranging from 49 to 316 ml/min. Optimal positioning of the DGW was identified at the position where maximum APV and M1/M0 were obtained. With optimal positioning the correlation between APV and M1/M0 was good (APV = 1.62 M1/M0 + 5.0; R2 = 0.98). Importantly, this correlation showed no dependence on the tube diameter. In vivo, in four patients APV and M1/M0 measurements were obtained in 16 coronary artery segments in one left anterior descending, two circumflex, and two right coronary arteries. In 10 vessel segments, there was no discrepancy between the measured and expected M1/M0 after positioning the DGW with help of the Doppler signal quality only. In six vessel segments, repeat DGW positioning using M1/M0 was necessary, yielding an average increase of APV of 20% (7-38%). We conclude that DGW positioning can be optimized using the correlation between APV and M1/M0 as a reference. For any given APV value, there is a corresponding expected value for M1/M0 under the condition of optimal positioning. Any discrepancy between the measured and expected values for M1/M0 then indicates suboptimal positioning.

Blood Flow Velocity↗
PubMed1998

Impact of Doppler guidewire size and flow rates on intravascular velocity profiles.

Coronary blood flow velocity measurements by conventional intravascular catheter-based Doppler devices are well known to be affected by catheter size. Moreover, it is of clinical importance that the assessment of maximum vasodilator capacity, i.e., the coronary reserve, might be considerably affected by a shape change of the velocity profile under hyperemia. Therefore, the present in vitro study aimed to assess the impact of a small-size Doppler guidewire on the velocity profiles interrogated in tubes with diameters corresponding to the epicardial coronary arteries at clinically relevant flow rates. A 0.014" guidewire was inserted into four serially connected silicone tubes of known diameter, which were perfused with discarded human whole blood by means of a roller pump. In order to determine the effect of the Doppler guidewire on the velocity profile antegrade and retrograde perfusion were carried out in each vessel segment. Vm, the true mean velocity, was calculated from the time collected flow divided by the corresponding vessel cross-sectional area. Average peak velocity (APV) measurements were obtained by pulling back the Doppler device across each of the four vessel segments with given flow rates ranging from 1.14-5.88 ml/s in antegrade and retrograde direction. The shape factor of the recorded velocity profile (fp) is defined as vm/APV and is generally assumed to be close to 0.5. Antegrade perfusion: APV = 1.63 vm + 5.35 (R2 = 0.98); fp = 0.001 vm + 0.51. Retrograde perfusion: APV = 1.71 vm + 3.33 (R2 = 0.98); fp = 0.001 vm + 0.52. Due to the constant relationship between APV and vm, velocity profiles within vessels of epicardial coronary artery size are not substantially disturbed by the presence of the Doppler guidewire. The slight, but significant increase of experimental fp with increasing flow is at variance with the theoretically expected fp values.

Blood Flow Velocity↗
PubMed1998

Teichoic acid content in different lineages of Staphylococcus aureus NCTC8325.

A series of mec transformants of Staphylococcus aureus strain NCTC8325 were analysed for alterations in wall teichoic acid and lipoteichoic acid. Although the methicillin resistance determinant alters the autolytic behaviour of S. aureus, it had no effects on the cellular content, chain length, and alanine substitution of the lipoteichoic acid, or on the wall teichoic acid content and composition. However, independently of the presence or absence of the methicillin resistance determinant, level of methicillin resistance, or autolytic behaviour, a correlation was found between a 25% reduced cell wall phosphate content and either loss of prophages phi11 and 13 or a 30-kb deletion in the chomosmal SmaI-F fragment adjacent to the prophage &phi;11 attachment site.

Acetylglucosamine↗
PubMed1998

Inflammatory aneurysm of the ascending aorta.

The gold standard to clarify an acute pathology of the ascending aorta is transesophageal echocardiography or contrast-enhanced computed tomography. Neither of these methods led to the correct finding in our case of an inflammatory aneurysm of the ascending aorta. Both assessments resulted in the diagnosis of an acute dissection of the ascending aorta.

Aortic Dissection↗
PubMed1998

Long-term follow-up in hypertrophic obstructive cardiomyopathy after septal myectomy.

BACKGROUND: Controversy exists about the choice of treatment for patients with hypertrophic obstructive cardiomyopathy. The purpose of this study was to evaluate clinical and echocardiographic long-term results in patients with hypertrophic obstructive cardiomyopathy after septal myectomy and to determine predictors of event-free survival in these patients. METHODS: Between 1965 and 1995, 110 consecutive patients 2 to 66 years old (mean age, 37 +/- 15 years) with an invasively measured left ventricular outflow tract gradient of 86 +/- 39 mm Hg (81 +/- 42 mm Hg by Doppler echocardiography) underwent either septal myectomy only (n = 87) or myectomy combined with additional procedures (n = 23). Mean follow-up was 11.7 +/- 7.5 years. Predictors of late events were calculated using multivariate Cox regression analysis. RESULTS: The perioperative mortality rate was 3.6% (n = 4). The cumulative survival rate at 5, 10, and 15 years was 93%, 80%, and 72%, respectively, and symptom-free survival, 77%, 50%, and 33%, respectively. Predictors of late death were New York Heart Association class III or IV (p < 0.05), congestive heart failure (p < 0.05) and additional procedures (p < 0.05). The left ventricular outflow tract gradient was nearly eliminated in all patients, the left atrial dimension decreased significantly during the early years, and left ventricular dilatation occurred late in 17 patients. CONCLUSIONS: Septal myectomy is associated with a low perioperative mortality and a high late survival rate (72% at 15 years' follow-up). Septal myectomy is still an excellent modality in the treatment strategy for symptomatic patients with hypertrophic obstructive cardiomyopathy.

Adolescent↗
PubMed1998

Cardiac risk after mediastinal irradiation for Hodgkin's disease.

PURPOSE: To evaluate the risk of cardiac lesions after conventionally fractionated irradiation (Rt) of the mediastine with or without chemotherapy (Ct) in patients with Hodgkin's disease (HD) and to relate them to known cardiovascular risk factors. PATIENTS AND METHODS: Between 1964 and 1992, 352 (total group) patients with HD were treated with curative intention using Rt with or without Ct including the mediastine and had a follow-up of at least 1 year. More than 96% of the patients had a complete follow-up. One hundred forty-four patients (64% of the living patients, heart study group) have regular follow-up in our department and had a special heart examination including rest and exercise ECG, echocardiography and myocardial perfusion scintigraphy (112 patients). Doses per fraction in the anterior heart region were between 1.3 and 2.1 Gy. Total doses were between 30.0 and 42.0 Gy in 93% of cases. The mean length of follow-up was 11.2 years (range 1.0-31.5 years). Other cardiovascular risk factors evaluated were body mass index, blood pressure, smoking history, diabetes mellitus, hypercholesterolemia and history of coronary artery disease before Rt. RESULTS: In the total group, the risk of fatal cardiac ischemic events and/or of sudden unexpected death was significantly higher than expected with a relative risk of 4.2 for myocardial infarction and 6.7 for myocardial infarction or sudden death. In female patients and in patients without other cardiovascular risk factors, the risk of fatal or non-fatal ischemic cardiac events was not significantly different from the expected value. In the subgroup with no cardiovascular risk factors and treatment without Ct, there was no ischemic or other major cardiac event. Echocardiography showed valvular thickenings in a large amount of the patients (the cumulative risk after 30-year follow-up was above 60%) but mostly without hemodynamic disturbance. In patients without hypertension and without coronary artery disease, findings of perfusion scintigraphy and echocardiographic evaluation of systolic and diastolic function were normal. Treatment with Ct was not a significant risk factor for cardiac events but the number of patients whose treatment included adriamycin and with a follow-up exceeding 10 years is to low for a definitive evaluation. CONCLUSIONS: In patients without the usual cardiovascular risk factors (smoking, hypertension, obesity, hypercholesterolemia, diabetes mellitus) the risk of serious cardiac lesions after conventionally fractionated irradiation of the mediastinum with an intermediate total dose between 30 and 40 Gy is low. Also the cardiac risk of the combination of this irradiation with Ct including adriamycin with a total dose between 200 and 300 mg/m2 seems low but further long-term observation is necessary.

Adolescent↗
PubMed1998

Echogenic structures in the left atrioventricular groove: diagnostic pitfalls.

A variety of echogenic structures that can be detected by echocardiography in the left atrioventricular groove are best seen in the parasternal long-axis view and can be missed if not carefully looked for. Normal anatomic structures or variants can be seen, for example, dilated coronary sinus, persistent left superior vena cava, or lipomatous tissue. Degenerative or inflammatory processes of the mitral annulus (calcification of the mitral annulus, mitral annular abscess) and aneurysms of the left circumflex coronary artery or of the descending aorta can depict pathologic structures. Hiatal hernia and tumors can be found as well.

Aortic Aneurysm, Thoracic↗
PubMed1998

Systolic and diastolic function with alternate and combined site pacing in the right ventricle.

UNLABELLED: We hypothesized that pacing at two ventricular sites simultaneously would activate the myocardium more rapidly and improve ventricular function. We studied the effect of pacing at the right ventricular outflow tract (RVOT) and the RV apex (RVA) on systolic and diastolic function. In 14 patients with a reduced systolic ejection fraction < 40% (mean EF 32% +/- 4%) we measured RV pressures, left ventricular pressures, EF, cardiac output, peak dP/dt, peak negative dP/dt, and the time constant of relaxation, Tau, during intrinsic rhythm, atrial pacing and DVI pacing at the RVA, the RVOT, and both RV sites combined in random order. Repeated measures analysis of variance showed no significant differences in any of these parameters. The highest absolute values of dP/dt were observed during sinus rhythm and the lowest with RVA pacing. This parameter tended to improve progressively with pacing in the RVOT and at both sites. Peak negative dP/dt showed a similar nonsignificant trend. CONCLUSION: These data suggest that in patients with poor LV function, there may be subtle improvements in diastolic and systolic function with pacing in the RVOT and at combined sites in the RV compared to traditional RVA pacing.

Analysis of Variance↗
PubMed1998

Long-term follow up of patients with endomyocardial fibrosis: effects of surgery.

AIMS: To determine the long-term outcome of patients with endomyocardial fibrosis and to compare echocardiographic and haemodynamic data before and after ventricular endocardial resection. PATIENTS: Seventeen patients (11 women and six men; mean age 35.5 years) diagnosed with endomyocardial fibrosis at the University Hospital in Zurich, Switzerland from 1971 to 1995. Twelve patients (70%) had partial obliteration of both ventricles and in five patients (30%) the fibrotic lesions were limited to the left ventricle. METHODS: Fourteen of the 17 patients had surgical resection: fibrosis was resected from both ventricles in five patients and from the left ventricle only in nine patients. Ten patients had mitral valve replacement and two had tricuspid valve replacement. Left ventricle endocardial resection was done without reconstruction or replacement of the atrioventricular valve in three patients. Preoperative and postoperative echocardiographic data were available for 11 patients and haemodynamic data for six patients. Patients were followed up for 0.4-19 years (mean 8.6). RESULTS: Preoperatively four patients were NYHA functional class IV and 10 were class III; postoperatively one patient was class III, seven class II, and six class I. Preoperatively, echocardiography showed obliteration of the left ventricular apex and inflow tract in all patients, which decreased or disappeared after surgery. Left ventricular end diastolic pressure decreased from 25 mm Hg before surgery to 14 mm Hg after successful resection of the fibrosis. Left ventricular and diastolic volume (normal 93 (17) ml/m2) increased from 65 ml/m2 to 97 ml/m2 (p < 0.05) after surgery. Ejection fraction was normal preoperatively (57%) and decreased slightly (52%) after surgery. One patient died five months after surgery from heart failure. Four surgically treated patients died during the follow up period: one each from systolic dysfunction, recurrence of endomyocardial fibrosis, pneumonia, and food poisoning. Overall survival was 65% at five years and 59% at 10 years; the survival rates of the operated patients was 72% and 68%, respectively. Only one of the medically treated patients survived longer than three years from diagnosis. CONCLUSIONS: Endomyocardial fibrosis is a rare disease in European countries and is found mainly in women. The clinical picture is characterised by severe congestive heart failure but heart size is only moderately increased. Systolic performance is normal or only slightly depressed despite severe restriction to filling, atrioventricular valve regurgitation or both. Partial obliteration of the right and/or left ventricle may be detected by echocardiography. Endocardial resection with atrioventricular valve replacement is the treatment of choice with appreciable postoperative improvement and 10 year survival of approximately 70%.

Adolescent↗
PubMed1997

[Aortic valve insufficiency in Crohn disease].

We report on a 39-year-old man with Crohn's disease who was admitted with cardiogenic shock after a short history of progressive dyspnea. Echocardiographic examination (transthoracic echocardiography) showed severe aortic regurgitation, mild mitral regurgitation, and enlargement of the sinus of Valsalva and of the ascending aorta at the level of the right pulmonary artery. The left ventricular ejection fraction was 30%. After aortic valve replacement, histologic examination of the ascending aorta showed chronic aortitis resembling syphilitic aortitis (serology for syphilis was negative) and HLA B27 related aortitis. The aortic valve showed deformation and thickening of the cusps by fibrous tissue without evidence of endocarditis. The patient remained well after surgery and echocardiographic examination 6 months later showed normal function of the aortic valve prosthesis. The diameter of the sinus of Valsalva and of the ascending aorta was slightly bigger, possibly indicating ongoing destruction. The left ventricular ejection fraction nearly normalized. It seems possible that this type of aortitis, characterized by its proximity to the valve ring, is another extraintestinal cardiac manifestation of Crohn's disease. The possibility of ongoing destruction of the sinus of Valsalva and of the ascending aorta after valve replacement makes regular echocardiographic control necessary.

Adult↗
PubMed1997

[Early results in the surgical treatment of type B aortic dissection].

In contrast to type A aortic dissection, the indication for acute surgical repair as treatment of choice in type B aortic dissection is not the actual dissection, but the complications resulting from the dissection (rupture, potential rupture and ischemic syndromes of the aortic branches). Between 1978 and 1994, 92 patients underwent surgical repair of type B aortic dissection at our institution. Following diagnostic confirmation by echocardiography and/or CT scan, all patients received conservative antihypertensive therapy. 52% of the patients underwent emergency surgical repair. Symptoms prompting surgical repair were: visceral ischemia (23%), pleural effusion (19%), paraparesis (17%), refractory hypertension (12%), further aortic enlargement (12%), and rupture (10%). In chronic type B aortic dissection, the main symptom in 84% of the cases was further enlargement of the aorta. The early mortality decreased in the course of initial treatment from 33% to 16%, and to 8% after exclusion of patients operated on for ruptured aorta. Improved early mortality has led to an increase in acute surgical repair. In cases of chronic dissection, strict antihypertensive therapy is indicated and regular checks on the width of the aorta, as well expeditious diagnostic confirmation of its enlargement, are important.

Acute Disease↗