Characteristics of Bifocal Pacing:

Bifocal RIGHT ventricular stimulation (BRIGHT) is an ongoing, randomized, single-blind, crossover study of atrial synchronized bi-right ventricular (RV) pacing in patients in New York Heart Association heart failure functional class III, a left ventricular ejection fraction <35%, left bundle branch block and QRS complexes ≥120 ms. This analysis compared the electrical and handling characteristics, and the complications of pacing at the RV apex (Ap) with passive, versus RV outflow tract (OT) with active fixation leads. A mean of 1.6 ± 0.9 and 2.2 ± 2.0 attempts were needed to position the Ap and OT leads, respectively (ns). R-wave amplitudes at Ap versus OT were 23 ± 13 mV versus 14 ± 8 mV (n = 36, P < 0.001). R-wave amplitudes at the Ap remained stable between implant and M7. R-wave amplitudes at the OT could not be measured after implantation. In two patients, atrioventricular block occurred during active fixation at the OT. Conduction recovered spontaneously within 4 months. Ventricular fibrillation was induced in one patient during manipulation of an Ap lead in the RV. Marked differences were found between leads positioned in the OT versus Ap, partly related to the difference in lead design. Mean R-wave amplitude was higher at the Ap that at the OT. Ease and success rate of lead implant was similar in both positions.     

Chronic fatigue syndrome: a clinical and laboratory study with a well matched control group

Abstract. Objective. To investigate the relation between severity of complaints, laboratory data and psychological parameters in patients with chronic fatigue syndrome (CFS). Subjects. Eighty-eight patients with CFS and 77 healthy controls matched for age, sex and geographical area. Methods. Patients and controls visited our outpatient clinic for a detailed medical history, physical examination and psychological tests: Checklist Individual Strength (CIS), Beck Depression Inventory (BDI) and Sickness Impact Profile (SIP). Venous blood was drawn for a complete blood cell count, serum chemistry panel, C-reactive protein and serological tests on a panel of infectious agents. Results. All patients fulfilled the criteria for CFS as described by Sharpe et al. (J R Soc Med 1991; 84 : 118–21), only 18 patients (20.5%) fulfilled the CDC criteria. The outcome of serum chemistry tests and haematological tests were within the normal range. No significant differences were found in the outcome of serological tests. Compared to controls, significant differences were found in the results on the CIS, the BDI, and the SIP. These results varied with the number of complaints (CDC criteria). When the number of complaints was included as the covariate in the analysis, there were no significant differences on fatigue severity, depression, and functional impairment between patients who fulfilled the CDC criteria and patients who did not. Conclusion. It is concluded that the psychological parameters of fatigue severity, depression and functional impairment are related to the clinical severity of the illness. Because the extensive panel of laboratory tests applied in this study did not discriminate between patients and controls, it was not possible to investigate a possible relation between the outcomes of psychological and laboratory testing.     

Fractional Flow Reserve: The Ideal Parameter for Evaluation of Coronary, Myocardial, and Collateral Blood Flow by Pressure Measurements at PTCA

To overcome the fundamental limitations of coronary arteriography to assess the functional significance of coronary artery disease, it is necessary to obtain direct information about coronary blood flow. Recently we validated three pressure flow equations, which enable calculation of maximum coronary, myocardial, and collateral flow by merely measuring aortic, central venous, and distal coronary pressures under the condition of maximum vasodilation and using an ultra thin pressure monitoring guide wire for distal coronary pressure recording. In this paper, the first clinical experiences of this method are described. For that purpose, the concept of fractional flow reserve (FFR) is important. Fractional coronary flow reserve (FFR_cor) is defined as the maximum achievable blood flow in a stenotic artery, divided by normal maximum flow in that same artery, i.e. maximum flow in that artery in the case that it would be completely normal. Fractional myocardial flow reserve (FFR_myo) is defined in a similar way, and recruitable collateral blood flow is expressed as a fraction of normal maximum myocardial flow. Fractional flow reserve, defined in this way, is easy to obtain at percutaneous transluminal coronary angioplasty (PTCA) by the pressure-flow equations, is independent of pressure changes, applicable to three vessel disease, and enables calculation of the separate contribution of coronary and collateral flow to total myocardial perfusion. In 18 patients a very close correlation was demonstrated between FFR_myo, calculated by pressure recordings at PTCA by the first pressure flow equation, and FFR_myo obtained by positron emission tomography, which is considered the gold standard for myocardial perfusion. In 60 other patients, maximum recruitable collateral blood flow at balloon inflation (Q_c/Q^N) was calculated according to the third pressure-flow equation and correlated to the presence or absence of ischemia. It could be demonstrated that Q_C/Q^N exceeds 22% in all 23 patients without ischemia, whereas Q_c/Q^N was less than 22% in 34 out of 37 patients who experienced ischemia during balloon inflation. This margin value of 22% is very close to the theoretically expected value of 20%. based upon a coronary flow reserve of 5 under standard physiologic conditions. It can be concluded that the concept of fractional flow reserve provides a rapid, accurate, and elegant way for quantitative assessment of maximum coronary and myocardial blood flow before and after PTCA. Moreover, this is the first method that enables quantitative calculation of collateral blood flow in clinical practice. (J Interven Cardiol 1993; 6:331–344)     

Lability of N-alkylated peptides towards TFA cleavage

Trifluoroacetic acid (TFA) is a common reagent in both solid-phase and solution peptide synthesis. It is used for the deprotection and/or cleavage of the synthesized peptide from the resin. The use of TFA under these standardized conditions is thought to be sufficiently mild, thereby preventing degradation of the desired product. However, peptides of the general structure R¹-(N-alkyl X₁)-X₂-R² are hydrolyzed by standard TFA solid-phase peptide synthesis (SPPS) cleavage/deprotection conditions providing fragments R¹-(N-alkyl X₁)-OH and H-X₂-R². The fragmentation is observed during a TFA cleavage both from the resin and in solution. The hydrolysis is proposed to proceed via an oxazolone-like intermediate in which equilibration of the chiral center of the N-alkylated residue occurs. This mechanism is supported by H/D exchange as observed by MS and NMR in conjunction with HPLC. © Munksgaard 1996.     

Differences in production between medical specialists: An inventory based on claims data to identify potential areas for quality-improvement activities

Claims data from sickness funds were used to describe practicepatterns of all physician partnerships of six medical specialtiesin a region of The Netherlands. The numbers of admissions tohospital, patient days, in-patient and out-patient procedureswere compared per 1,000 insured persons. There were large differencesamong physicians within the same specialties. The non-surgicalspecialties had more variable practice patterns. Variation inuse of specific procedures with a supposedly clear indicationversus a less-defined indication was the same. We could notidentify special areas with greater differences that shouldhave a priority for quality-improvement activities. The useof sickness fund data in monitoring and decreasing variationsin medical practice is discussed.     

Solid-phase synthesis and conformational studies of helper T cell immunogenic peptides that carry carbohydrate haptens linked to serine

N ^α-Fmoc serine and its corresponding pentafluorophenyl ester were glycosylated with the 1,2-trans peracetates of the disaccharides galabiose and cellobiose. Complete stereoselectivity and 52-75% yields were obtained under boron trifluoride etherate promotion. Lower yields and loss of stereoselectivity were obtained when thioglycosides. trichloroacetimidates or glycosyl bromides were employed as glycosyl donors. The glycosylated building blocks were used in solid-phase synthesis of derivatives of a helper T cell immunogenic peptide consisting of amino acids 52-61 from hen-egg lysozyme. ¹H-NMR spectroscopy in DMSO-d₆ showed that the peptide moiety of the glycopeptides assumed random conformations which were not influenced by glycosylation at different positions.     

Correlation of Heart Rate Variability Parameters and QT Interval in Patients After PTCA of Infarct Related Coronary Artery as an Indicator of Improved Autonomic Regulation

The purpose of this study was to determine if PTCA of the infarct related coronary artery (IRA) in the late phase of myocardial infarction (MI) can improve autonomic regulation of sinus rhythm and electrical stability of the myocardium measured by heart rate variability (HRV), QT, QTc, and its dispersion (QTd) and if any correlation exists among these measures. The study was performed in 25 patients (21 male, age: 50 ± 9 years, EF: 52%± 11%) in the late phase of MI (2.5 ± 1.5 months). HRV parameters were calculated automatically. QT, QTc, and QTd were measured manually from a 12-lead surface ECG (50 mm/s). All measurements were made before and 3–5 days after PTCA. Day and night parameters of HRV were sampled over two periods: 2 pm to 10 pm (day) and 10 pm to 6 am (night). Parameters of HRV measured from whole recordings were significantly higher after successful PTCA: SDRR (116 31 vs 128 ± 38 ms), SD (55 ± 17 vs 62 ± 22 ms), rMSSD (30 ± 13 vs 36 ± 14 ms) and HF (246 ± 103 vs 417 ± 224 ms2). Significant differences were found during daytime for SD, rMSSD, and HF, and during nighttime for SDRR, SDANN. QT interval duration, QT corrected to the heart rate, and QT dispersion were significantly lower after PTCA (QTd: 54 ± 15 vs 39 ± 12 ms). There was no correlation between HRV and QT values before PTCA. High correlations were found after the procedure, particularly between QTd and nighttime HRV. Conclusions: PTCA of IRA in the late phase of MI enhances sympathovagal regulation of the cardiac rhythm and the electrical stability of the heart, which may be prognostically important.     

Presence of Streptococcus mutans and lactobacilli in saliva and on enamel, glass ionomer cement, and composite resin surfaces

Abstract— The quantity of S. mutans , total streptococci, and lactobacilli on sound enamel surfaces and 1-yr-old glass ionomer cement and composite resin fillings with the cervical margins placed subgingivally was compared intraindividually. The amount of bacteria was compared to their number in saliva. The evaluation was done in a cross sectional study, where the patients continued to use their customary oral hygiene procedures and during a 14-day period of experimental plaque formation. The number of lactobacilli and S. mutans recovered from the test surfaces indicated that the critical salivary concentrations necessary for the isolation of S. mutans and lactobacilli from glass ionomer cement and composite resin surfaces are the same as for the enamel surfaces. The fluoride levels in plaque adjacent to glass ionomer cement will not become high enough to inhibit the accumulation of the investigated bacteria.     

Well-being and future sick-leave: Multivariate analyses with regard to preceding sick-leave

Consistent associations between self-rated well-being and futuresick-leave have previously been noted in a selected group ofrepeated short-term sick-leavers. The object was to retest thoseassociations after ruling out expected influences of precedingsick-leave. Hypothetically the well-being-sick-leave linkagesinitially observed would thereby overlap with the behaviouralconformity over time. Accordingly, they would possibly be erasedin a hierarchical stepwise regression analysis. The study groupcomprised 61 females and 62 males with diffuse reasons for theirhigh repeated sick-leave. Instead of having to present a doctor'scertificate on every new sick-leave occasion, they chose totake part In a support programme. Altogether 8 hierarchicalmultiple regression analyses were run with sick-leave occasionsand days the first and second years after the contact as separatedependent variables. In the first step, long-term behaviouralproneness to sickness absence was evaluated, i.e. the correlationsbetween the sick-leave parameters the year before and each ofthe 2 years after the programme were computed. In the secondstep, the possible additional impact of well-being ascertainedat entrance Into as well as exit from the clinical contact wasestablished. Sick-leave correlated strongly over the study periodsas expected. Yet, fairly consistent associations between well-beingand future sick-leave remained. The well-being parameters accountedfor another 4–8% of the entire variance in 5 of the 8regression analyses performed. That increment corresponded tobetween 25 and 100% of the proportion initially explained bypreceding sick-leave. Thus the independent role of perceivedself-image for the long-term inclination to sickness absencein the current ‘risk’ group was underscored. Thiswas particularly so since the influence of several other backgroundand job-related factors have previously proven to be empiricallynegligible. Moreover, similar prospective correlations havebeen seen in other study groups.