Improving the peri-operative pathway of people with diabetes undergoing elective surgery: the IP3D project

AIM

To determine whether outcomes for people with diabetes undergoing elective surgery improve following the introduction of innovations in the peri-operative care pathway.

METHODS

Following a baseline audit of 185 people with diabetes listed for elective surgery (July to December 2017) with a length of stay > 24 hours, a number of changes in practice were implemented. These included dissemination of a 'diabetes peri-operative passport' to participants preoperatively, formation of a diabetes surgery working group, recruitment of surgical diabetes champions and the roll-out of surgical diabetes study days. Crucial was recruitment of a diabetes peri-operative nurse, whose role included engaging and educating others and supporting individuals throughout their peri-operative diabetes care. Records of 166 individuals listed for surgery during the implementation period (July to December 2018) were then audited using the same methodology.

RESULTS

The availability of a recent HbA_1c measurement significantly increased (63% vs 92%; P ≤ 0.001). The mean HbA_1c of those seen for optimizations by the diabetes peri-operative nurse significantly decreased [84 mmol/mol (9.8%) vs 62 mmol/mol (7.8%); P ≤ 0.001]. Recurrent hypoglycaemia significantly decreased (7.0% vs 0.6%; P = 0.002) and the mean number of hyperglycaemic events in people experiencing hyperglycaemia almost halved (3.0 vs 1.7; P=0.007). The mean length of hospital stay significantly decreased (4.8 vs 3.3 days; P=0.001) and, crucially, 30-day readmissions did not increase (12% vs 9%; P=0.307). Postoperative complications significantly decreased (28% vs 16%; P=0.008), including a composite of dysglycaemic complications, poor wound healing, wound infection and other infections (12% vs 5.4%; P=0.023).

CONCLUSION

The new pathway improved important peri-operative outcomes for people with diabetes undergoing elective surgery with the potential for cost savings. These findings could have important implications for peri-operative care on a wider scale.

Guidelines for the management of diabetes services and patients during the COVID-19 pandemic

The UK National Diabetes Inpatient COVID Response Group was formed at the end of March 2020 to support the provision of diabetes inpatient care during the COVID pandemic. It was formed in response to two emerging needs. First to ensure that basic diabetes services are secured and maintained at a time when there was a call for re-deployment to support the need for general medical expertise across secondary care services. The second was to provide simple safe diabetes guidelines for use by specialists and non-specialists treating inpatients with or suspected of COVID-19 infection. To date the group, comprising UK-based specialists in diabetes, pharmacy and psychology, have produced two sets of guidelines which will be continually revised as new evidence emerges. It is supported by Diabetes UK, the Association of British Clinical Diabetologists and NHS England.

Perioperative passport: empowering people with diabetes along their surgical journey

AIM

To determine whether a handheld 'perioperative passport' could improve the experience of perioperative care for people with diabetes and overcome some of the communication issues commonly identified in inpatient extracts.

METHODS

Individuals with diabetes undergoing elective surgery requiring at least an overnight stay were identified via a customized information technology system. Those allocated to the passport group were given the perioperative passport before their hospital admission. A 26-item questionnaire was completed after surgery by 50 participants in the passport group (mean age 69 years) and by 35 participants with diabetes who followed the usual surgical pathway (mean age 70 years). In addition, the former group had a structured interview about their experience of the passport.

RESULTS

The prevalence of those who reported having received prior information about their expected diabetes care was 35% in the control group vs 92% in the passport group (P<0.001). The passport group found the information given significantly more helpful (P<0.001), including the advice on medication adjustment (P=0.008). Furthermore, those with the passport were more involved in planning their diabetes care (P <0.001), less anxious whilst in hospital (P<0.044) and better prepared to manage their diabetes on discharge (P≤0.001). The mean length of hospital stay was shorter in the passport group, although the difference did not reach significance (4.4 vs 6.5 days; P<0.058). Content analysis indicated that the passport was well liked and innovative.

CONCLUSION

Our data indicate that the perioperative passport is effective in both informing and involving people in their diabetes care throughout the perioperative period.

Neutralizing BAFF/APRIL with atacicept prevents early DSA formation and AMR development in T cell depletion induced nonhuman primate AMR model

Depletional strategies directed toward achieving tolerance induction in organ transplantation have been associated with an increased incidence and risk of antibody-mediated rejection (AMR) and graft injury. Our clinical data suggest correlation of increased serum B cell activating factor/survival factor (BAFF) with increased risk of antibody-mediated rejection in alemtuzumab treated patients. In the present study, we tested the ability of BAFF blockade (TACI-Ig) in a nonhuman primate AMR model to prevent alloantibody production and prolong allograft survival. Three animals received the AMR inducing regimen (CD3-IT/alefacept/tacrolimus) with TACI-Ig (atacicept), compared to five control animals treated with the AMR inducing regimen only. TACI-Ig treatment lead to decreased levels of DSA in treated animals at 2 and 4 weeks posttransplantation (p < 0.05). In addition, peripheral B cell numbers were significantly lower at 6 weeks posttransplantation. However, it provided only a marginal increase in graft survival (59 ± 22 vs. 102 ± 47 days; p = 0.11). Histological analysis revealed a substantial reduction in findings typically associated with humoral rejection with atacicept treatment. More T cell rejection findings were observed with increased graft T cell infiltration in atacicept treatment, likely secondary to the graft prolongation. We show that BAFF/APRIL blockade using concomitant TACI-Ig treatment reduced the humoral portion of rejection in our depletion-induced preclinical AMR model.

Dysregulated immunophenotypic attributes of plasmacytoid but not myeloid dendritic cells in HIV-1 infected individuals in the absence of highly active anti-retroviral therapy

Dendritic cells (DC) in HIV-1-infected individuals are decreased and their dysfunction has been implicated in HIV-1 immunopathogenesis. The mechanism of their dysfunction remains unclear, thus we analysed the expression of membrane molecules associated with immune regulation and DC activation in myeloid (mDC) and plasmacytoid DC (pDC) in therapy-naive and highly active anti-retroviral therapy (HAART)-treated HIV-1(+) patients. DC from healthy controls, untreated HIV-1(+) and HAART-treated patients were assessed by flow cytometry for expression of: anergy and apoptosis inducing molecules [programmed death (PD)-1 and its ligands PD-L1 and PD-L2], inhibitory and regulatory T cell-inducing molecules [immunoglobulin-like transcript (ILT)-3 and ILT-4], interferon (IFN)-α inhibitory receptor (ILT-7) and co-stimulatory molecules (CD80, CD83, and CD86). pDC from untreated HIV-1(+) patients expressed significantly lower levels of ILT-7 compared to healthy controls, while HAART-treated patients showed normal expression. pDC were also found to express moderately higher levels of PD-L1 and ILT-3 and lower levels of PD-L2 receptors in untreated patients compared to controls and HAART-treated patients. No significant changes were observed in mDC. There were no associations between the percentages and levels of expression of these molecules by pDC and viral load or CD4 T cell count. In conclusion, pDC but not mDC from HIV-1(+) patients with active viraemia display higher levels of apoptosis and T regulatory-inducing molecules and may be predisposed to chronically produce IFN-α through down-regulation of ILT-7. HAART restored normal expression levels of these receptors.

Hand pattern indicates prostate cancer risk

BACKGROUND

The ratio of digit lengths is fixed in utero, and may be a proxy indicator for prenatal testosterone levels.

METHODS

We analysed the right-hand pattern and prostate cancer risk in 1524 prostate cancer cases and 3044 population-based controls.

RESULTS

Compared with index finger shorter than ring finger (low 2D : 4D), men with index finger longer than ring finger (high 2D : 4D) showed a negative association, suggesting a protective effect with a 33% risk reduction (odds ratio (OR) 0.67, 95% confidence interval (CI) 0.57-0.80). Risk reduction was even greater (87%) in age group <60 (OR 0.13, 95% CI 0.09-0.21).

CONCLUSION

Pattern of finger lengths may be a simple marker of prostate cancer risk, with length of 2D greater than 4D suggestive of lower risk.

Interrater reliability of the Antipsychotic Non-Neurological Side-Effects Rating Scale measured in patients treated with clozapine

The Antipsychotic Non-Neurological Side-Effects Rating Scale (ANNSERS) was developed to provide a comprehensive measure for rating non-neurological adverse drug reactions (ADRs) to antipsychotics. Although there were already available measures that adequately rated specific non-neurological ADRs, such as sexual side effects, a need was identified for a scale that comprehensively rated the full range of non-neurological ADRs commonly seen across the spectrum of first and second generation antipsychotic drugs, including metabolic and autonomic ADRs. This article reports on work to establish the interrater reliability of an early version and a later, more comprehensive version of the ANNSERS (versions 1 and 2, v1 and v2, respectively). The measures were administered in London centres to patients treated with clozapine. Trained clinicians rated the patients simultaneously and independently. Interrater reliability on the scores was calculated using the kappa coefficient method. The results (mean kappa coefficients of 0.77 and 0.72, respectively) indicate that substantial interrater reliability was achieved for both versions. Items for which the main basis for rating was laboratory investigations rather than patient interview were largely excluded from this study, and kappas were also not calculated for items with a low frequency (less than 10%) of endorsement. Samples of patients on other antipsychotics would be required to reliably calculate kappa coefficients for these items. In conclusion, the ANNSERS represents a clinically applicable research innovation, with good interrater reliability on clinician judged items, which is now available for the comprehensive assessment of non-neurological ADRs to antipsychotics, to aid the processes of clinical audit, research and drug discovery.

[Cardiac metastasis from a Merkel cell skin carcinoma. A case report]

The authors report the case of a cardiac metastasis of a Market cell skin tumour in a 72 year old woman, presenting with chest pain and infero-lateral myocardial ischaemia simulating an acute coronary syndrome. The diagnosis, suspected on echocardiography, was confirmed by thoracic CT scan. Markel cell carcinoma is a rare skin tumour classified among the malignant neuroendocrine tumours. It has a high metastatic potential, especially to the gastrointestinal tract and the lung. On the other hand, cardiac metastases are quite exceptionally rare.

[Exertional hypertension and sport]

Defining the normal range of blood pressure during exertion is not easy. Each type of exercise induces increased blood pressure that responds to a particular curve, and adaptation modes differ according to age, gender, physical condition, basal blood pressure, etc. The best studied is blood pressure measured on the arm using a cycloergometre. Classical publications established blood pressure curves according to heart rate during exercise. It appears that the best scale of reference for power developed occurs in individuals who can provide a very high degree of effort and in particular, athletes who are in very good training. According to some authors, hypertension on exertion would entail a poor prognosis, even in the absence of resting hypertension. Nevertheless, there is presently no well established therapeutic recommendation concerning exertion hypertension. This approach could depend on resting blood pressure and on the existence of other risk factors. For an athlete, pursuing physical activity is most often encouraged, sometimes after treatment or adjustment of its level.

Efficacy of a hepatitis C virus core antigen enzyme-linked immunosorbent assay for the identification of 'window-phase' blood donations

BACKGROUND AND OBJECTIVES

Recent studies have suggested that potentially infectious donations provided during the antibody-negative 'window' phase of hepatitis C virus (HCV) infection may be identified by testing for viral RNA or HCV core protein. We therefore evaluated the performance of an HCV antigen enzyme-linked immunosorbent assay (ELISA) for identification of window-phase donations and for prospective screening of blood donors.

MATERIALS AND METHODS

One-hundred and twenty-eight archived plasma donations containing HCV RNA, but lacking antibody to HCV (anti-HCV), were tested by using the HCV antigen ELISA, together with 9951 freshly collected serum and plasma specimens from blood donors.

RESULTS

HCV core antigen was detected in 94% (120/128) of window-phase plasma donations. Overall specificity in freshly collected blood donor specimens was 99.74%. Two putative window-phase donations containing HCV core protein and viral RNA were identified from paid plasma donors by prospective testing with the HCV antigen ELISA.

CONCLUSION

These results indicate that an HCV antigen ELISA can identify almost all (94%) of viraemic donations given during the seronegative window phase of infection. The performance of the HCV antigen ELISA appears to be suitable for large-scale screening of blood donations.

Comparison of metabolic expenditure during CAEP versus a test adapted to aerobic capacity (Harbor test) in elderly healthy individuals

Cardiopulmonary exercise tests are frequently used to test rate responsive pacemakers. The chronotropic assessment exercise protocol (CAEP) has been specifically proposed for the evaluation of rate responsive pacing systems. A mathematical method, based on CAEP measurements, was developed with a view of normalizing the exercise induced metabolic response. CAEP was compared to a tailored protocol (Harbor), adapted to the metabolic capacity of each patient. Harbor was set to keep the exercise duration within 10 minutes and achieve a workload as linear as possible. Metabolic parameters were continuously recorded by a cardiopulmonary system. Those data were used in the construction of slopes by the normalization method. The results of the tests performed in 16 elderly healthy patients showed no differences in metabolic or functional parameters. Slopes of the mathematical model were comparable (1.09 +/- 0.16 for CAEP vs 1.07 +/- 0.17 for Harbor), though both were higher than the value of 1, defined as normal. In both cases, linearity was confirmed by the coefficient of correlation (0.98 +/- 0.02 for CAEP and Harbor). In conclusion, no significant differences were found in the outcomes of the two protocols. Higher values of the slopes with the normalization method can be explained by the definition of the maximal predicted heart rate as 220--age, which is probably not appropriate for elderly, healthy, active subjects.

Dystrophin associates with caveolae of rat cardiac myocytes: relationship to dystroglycan

The possibility of an interaction between the cytoskeletal protein dystrophin and cell surface caveolae in the mammalian myocardium was investigated by several techniques. Caveolin (cav)-3-enriched, detergent-insoluble membranes isolated from purified ventricular sarcolemma by density-gradient fractionation were found to contain dystrophin and dystroglycan. Further purification of cav-3-containing membranes by immunoprecipitation using anti-cav-3-coated magnetic beads yielded dystrophin but not always dystroglycan. Electron microscopic analysis of precipitated material revealed caveola-sized vesicular profiles that could be double-labeled with anti-dystrophin and anti-cav-3 antibodies. In contrast, immunoprecipitation of membranes with anti-dystrophin-coated beads yielded both cav-3 and dystroglycan. Electron microscopic analysis of this material showed heterogeneous membrane profiles, some of which could be decorated with anti-cav-3 antibodies. To confirm that dystrophin and cav-3 were closely associated in cardiac myocytes, we verified that dystrophin was also present in immunoprecipitated cav-3-containing membranes from detergent extracts, as well as in sonicated extracts of purified ventricular myocytes. Confocal immunofluorescence microscopy of ventricular and atrial cardiac myocytes showed that the cellular distributions of cav-3 and dystrophin partially overlapped. Immuno-electron micrographs of thin sections of rat atrial myocytes revealed a fraction of dystrophin molecules that are in apparently close apposition to caveolae. These results suggest that a subpopulation of dystrophin molecules interacts with cardiac myocyte caveolae in vivo and that some of the dystrophin is engaged in linking cav-3 with the dystroglycan complex.

Comparative effects of bisoprolol and nitrendipine on exercise capacity in hypertensive patients with regular physical activity

The aim of this study was to evaluate the long-term effects of administering bisoprolol compared with nitrendipine on the duration of the exercise tolerated by male and female patients, aged 18-65 years, having mild to moderate hypertension and taking regular exercise. In this double-blind, randomized prospective study, 96 patients (85 men and 11 women, 48+/-10 years) formed two groups: 49 in the bisoprolol group, and 47 in the nitrendipine group. After a washout period of 14 days, either 10 mg of bisoprolol or 20 mg of nitrendipine was given daily over a treatment period of 12 weeks. During the treatment period, the stability of the physical training was monitored weekly by using a questionnaire. The results of two maximal triangular exercise tolerance tests (ETTs) on an ergometric bicycle performed at D0 under placebo and at D84 under active treatment were compared. No statistical difference was observed between both groups, concerning age, gender, morphologic characteristics, resting cardiovascular parameters, or physical training. Both groups maintained the same training level throughout the study. No significant differences between the groups were noted for duration of ETT [D0 892+/-284 s, D84, 919+/-267 s (NS) vs. D0 929+/-290 s, D84 904+/-324 s (NS)], or maximal work load [D0 190+/-49 W, D84 197+/-48 W (NS) vs. D0 198+/-49 W, D84 196+/-55 W (NS)]. On the other hand, both groups differed in maximal systolic blood pressure [D0 239+/-24 mm Hg, D84 215+/-22 mm Hg (p<0.001) vs. D0 237+/-24 mm Hg, D84 222+/-27 mm Hg (p<0.05)] (p = 0.05), and maximal pulse rate during exercise [141+/-18 vs. 163+/-17] (p<0.001), albeit not in maximal diastolic blood pressure [D0 113+/-13 mm Hg, D84 106+/-17 mm Hg (p<0.05) vs. D0 112+/-13 mm Hg, D84 104+/-15 mm Hg (p<0.05)]. The patient's own perception of the maximal effort (Borg scale) was not significantly different in either of the groups (placebo vs. treatment). Overall, in a population of hypertensive patients taking regular exercise, long-term treatment with bisoprolol produced no significant changes in the duration of peak effort, maximal workload, or the effort perceived by the patients themselves. The effects of regular exercise were comparable in both groups (bisoprolol or nitrendipine). Because previous studies have shown that dihydropyridines do not modify exercise performance in hypertensive patients, it may be concluded that the antihypertensive therapy with bisoprolol is well tolerated in a population of active hypertensive patients during dynamic exercise.

[Diagnostic use of oxygen consumption and gas exchange in exercise testing]

The interpretation of cardio-pulmonary exercise testing is usually performed on successive decisional organigrams which are based on the normality of two initial main branchpoints i.e., Vo2max and ventilatory threshold (VThr). This didactic approach leads however to a simplistic approach of exercise pathophysiology because the answer to the two original branchpoints (Vo2max and VThr) is mainly binary whereas the physiological meaning of these two parameters is multifactorial. Thus, we propose a methodic analytical approach which allows to integrate step by step the various informations concerning aerobic capacity, ventilatory and cardiocirculatory responses, and acidobasic status. After a purely descriptive analysis of data , a first synthesis describes the physiopathological behaviour during exercise and states the specificity of these informations excluding usual confounding factors. The comparison between the functional data and the clinical informations allows to propose some physiopathological hypothesis by confronting several complementary approaches: physiological, physiopathological and clinical ones. This method seems to be more adapted to the clinical diagnostic use of such a physiological investigation because it is sensitive, reproducible but not specific.

Water channel proteins in rat cardiac myocyte caveolae: osmolarity-dependent reversible internalization

We show by confocal immunofluorescence microscopy that the water channel protein aquaporin-1, not previously identified within cardiomyocytes, localizes at 20 and 37 degrees C to rat cardiomyocyte sarcolemmal caveolar membrane and subsarcolemmal cytoplasm of primary atrial myocyte cultures, dissociated atrial and ventricular myocytes, and in situ cardiomyocytes of atrial and ventricular frozen sections. Confocal immunofluorescence microscopy shows that the normal in situ colocalization of the quasi-muscle-specific caveolar coating protein caveolin-3 with aquaporin-1 is reversibly disrupted by exposing in situ atrial or ventricular myocytes to physiological saline made hypertonic by adding 150 mM sucrose or 75 mM NaCl to isotonic physiological saline. This causes caveolae to close off from the interstitium and swell, while aquaporin-1 is internalized reversibly. At 4 degrees C aquaporin-1 does not colocalize with caveolin-3. We suggest that 1) in vivo, under near-isotonic conditions, caveolae may alternate frequently between brief open and closed-off states; 2) aquaporin-1-caveolin-3 colocalization may be energy dependent; and 3) while closed off from the interstitium, each caveola transiently functions as an osmometer that experiences, monitors, and reacts to net water flow from or into the subcaveolar cytosol of the myocyte.

T-cadherin is a major glycophosphoinositol-anchored protein associated with noncaveolar detergent-insoluble domains of the cardiac sarcolemma

Sucrose-density flotation analysis of Triton-insoluble membrane domains isolated from highly purified sheep ventricular sarcolemma revealed the presence of two major 120- and 100-kDa proteins. Both species migrated in two-dimensional isoelectric focussing/SDS gels with an apparent pI of approximately 4.3, suggesting that they might be related. Microsequence analysis of peptides derived from the 100-kDa protein yielded amino acid sequences with high homology to T-cadherin, a truncated cadherin lacking a cytoplasmic domain. The similarity was confirmed using antibodies to chicken T-cadherin that reacted with both proteins on immunoblots. T-cadherin was released from the detergent-insoluble sarcolemmal fraction by phospholipase C treatment indicating that it is linked to the membrane by a glycophosphoinositol anchor. T-cadherin could be ADP-ribosylated by a transferase that was also present in the caveolin-enriched Triton-insoluble fraction. T-cadherin-containing membrane fragments cofractionated on sucrose gradients with caveolin-3, a marker protein for myocyte caveolae. However, immunopurified caveolin-3-containing membranes contained no associated T-cadherin. Immunocytochemical analysis of cultured rat atrial myocytes revealed that T-cadherin and caveolin have related but nonoverlapping staining patterns. These results suggest that T-cadherin is a major glycophosphoinositol-linked protein in cardiac myocytes and that it may be located in plasma membrane "rafts" distinct from but possibly adjacent to caveolae.

Effects of indomethacin and polyunsaturated fatty acid diet on exercise-induced hypoxaemia in master athletes

We have previously reported a reduction in exercise-induced hypoxaemia following polyunsaturated fatty acid supplementation (PUFA). Although this might have been explained by increases in membrane fluidity, a clear explanation could not be provided due to potentially confounding influences of series-2 prosta- glandin mediated effects resulting from PUFA. In this investigation, ten master athletes [mean age 48.1 (SEM 6) years, maximal oxygen uptake (VO2max) 3.39 (SEM 0.21) l x min(-1)] completed a maximal cycling test (Ctrl) which was repeated after the administration of 150 mg of indomethacin to inhibit prostaglandin synthesis, both before and after 6 weeks of 3.66-g PUFA x day(-1). Cardiorespiratory parameters were obtained simultaneously with brachial arterial blood sampling for partial pressure of oxygen in arterial blood (PaO2), partial pressure of carbon dioxide in arterial blood (PaCO2), pH, oxygen saturation in arterial blood and lactate concentration determinations. A significant decrease in PaO2 (mmHg) from rest [93 (SEM 1.5)] was observed for exercise intensities of more than 40% VO2max in Ctrl reaching 75.9 (SEM 2.1) at VO2max. PUFA resulted in a 5.0 (SEM 0.68) mmHg upward shift (P < 0.05) in the PaO2-oxygen uptake relationship, reducing the difference in partial pressure of oxygen between alveolar air and arterial blood (P(A-a)O2) at VO2max [Ctrl 36 (SEM 1.6) vs PUFA 33 (SEM 2.2) mmHg] while PaCO2, remained unchanged. Indomethacin had no effect on either PaO2, ideal partial pressure of oxygen in alveolar gas or P(A-a)O2 in either Ctrl or after PUFA. In contrast, the fall in pH was significantly reduced after indomethacin while VCO2, PaCO2 and lactacidaemia remained unchanged. These observations confirm an effect of PUFA on exercise PaO2 behaviour which does not appear to be mediated by the influence of a series-2 prostaglandin.

Quality control for qualitative assays: quantitative QC procedure designed to assure analytical quality required for an ELISA of hepatitis B surface antigen

An assay for hepatitis B surface antigen (HBsAg) should reliably detect 0.2 microgram/L, the lowest reported concentration in an asymptomatic blood donor. The difference between this concentration and the assay cutoff defines the analytical quality requirement in a total error format. The design of a statistical QC procedure is critically dependent on the precision of the assay. The precision of a developmental ELISA of HBsAg under study ranged from 17.5% to 9.6% for controls containing 0.07 to 1.50 micrograms/L, respectively. Use of one positive control with the 1(3s), QC rule provided an 85% chance of detecting a critical loss of assay sensitivity; use of two positive controls increased the chance of detecting critical loss of assay sensitivity to nearly 100%. These rules are based on the precision of this developmental assay, and must be developed individually for other assays. The development of the proposed QC procedures illustrates how quantitative QC can be provided for qualitative assays.

Type B atrial natriuretic peptide receptor in cardiac myocyte caveolae

We have previously shown that atrial natriuretic peptide (ANP) is present in caveolae of in situ rat atrial myocytes. To investigate whether intracaveolar ANP of rat atrial myocytes exists within caveolae bound to type B ANP receptors (ANP-RB, a guanylyl cyclase), we have used confocal immunofluorescence microscopy applied to primary cultures of atrial myocytes from adult rats and to freshly dissociated rat atrial myocytes (not cultured). These experimental designs tested whether atrial myocyte ANP-RB colocalizes at the plasmalemma and elsewhere in the cell with the muscle-specific isoform of the caveolar coating protein caveolin-3, and with a fraction of cellular ANP. The experiments showed that cellular caveolin-3, a fraction of cellular ANP-RB, and a fraction of cellular ANP colocalize at the plasmalemma of cultured atrial myocytes and of freshly dissociated atrial myocytes. The observations support the hypothesis that in rat atrial myocytes, intracaveolar ANP is bound to ANP-RB, a protein whose cytosolic amino acid sequences are known to encode guanylyl cyclase activity. We suggest that among the (probably multiple) effects of the cGMP thus generated in the cytoplasmic microdomain underlying atrial myocyte caveolae may be the activation of cGMP-dependent protein kinase, which would thereby inhibit plasma membrane Ca2+ channel activity and contribute to a negative inotropic effect of ANP.

Transient fall in oxygen intake during exercise in congestive heart failure

We report four cases in which oxygen intake abruptly decreased during a graded exercise test. In all these cases, there was an acute event (arrhythmia, mitral regurgitation) that had very likely resulted in a decrease in cardiac output. These studies provide new evidence of oxygen intake dependence on oxygen transport, even in nonsteady-state situations.

Cardiac output response to dynamic exercise after atrial switch repair for transposition of the great arteries

Results from this study showed that patients who underwent successful operation for transposition of the great arteries had no appropriate increase in stroke volume in response to exercise of a nature similar to common recreational activities. The impairment, most likely due to disturbances in both venous return and ventricular systolic function, is compensated for by an increase in peripheral oxygen extraction; however, this increase may not be adequate with maturation or during prolonged exercise when cardiovascular constraints are more important.

Maximal blood lactate level acts as a major discriminant variable in exercise testing for coronary artery disease detection in men

BACKGROUND

The interpretation of exercise stress testing for coronary artery disease detection is affected by the many differences in chosen variables and mathematical methods. We conducted a prospective trial to evaluate a global muscle fatigue parameter--the blood lactate level achieved at maximal exercise--as a method of distinguishing between diseased and nondiseased coronary status.

METHODS AND RESULTS

We evaluated 236 consecutive male patients without previous myocardial infarction who had been referred for the diagnosis of coronary artery disease. None of the patients had cardiomyopathy, severe cardiac heart failure, or valvular heart disease. Blood lactate concentration at maximal exercise was measured as well as other classic variables. Correlations between variables and coronary status as assessed by coronary arteriography were described using receiver operating characteristic (ROC) curves and logistic regression analysis. The first four most powerful variables (lactate level, maximal power output, exercise duration, and percentage of maximal predicted heart rate), which are directly representative of the global functional capacity, showed values of 0.777, 0.775, 0.760, and 0.740, respectively, by ROC curve analysis. Mean +/- SD blood lactate level at peak exercise reached 7.68 +/- 2.70 mmol/L in the 153 diseased and 10.56 +/- 2.75 mmol/L in the 83 nondiseased patients (P < .0001). After adjustment for other variables, blood lactate level remained a significant predictor of coronary artery disease by logistic regression analysis (adjusted odds ratio, 1.2; confidence interval, 1.04 to 1.4).

CONCLUSIONS

Global muscle fatigue as assessed by lactate levels in the blood at maximal exercise appears to be a powerful distinguisher of diseased and nondiseased coronary status.

Standardization of absolute CD4+ lymphocyte counts across laboratories: an evaluation of the Ortho CytoronAbsolute flow cytometry system on normal donors

The Ortho CytoronAbsolute is a flow cytometer designed to provide direct absolute counts of lymphocytes and their subsets from a single instrument. This study was designed to determine the performance of four geographically separated CytoronAbsolute instruments using 24-h-old, shipped, whole blood samples and to compare the results obtained on the CytoronAbsolute to those obtained using combinations of hematology instruments and other flow cytometers. The absolute count feature of the CytoronAbsolutes located at the four sites were cross calibrated and gave across-site coefficients of variation (CVs) of <4.0% for absolute count and 8.2% for absolute lymphocyte count. The calibration was stable for at least 2 months. Absolute lymphocyte counts and lymphocyte percentage immunophenotypes were determined on blood from 50 healthy human immunodeficiency virus (HIV)-seronegative donors. There were no significant site-to-site differences (each P > .05) in CD3+/CD4+ absolute lymphocyte counts determined on the CytoronAbsolute. In contrast, there was a significant site-to-site difference (P < .001) between sites 2 and 3 and sites 3 and 4 in the absolute CD3+/CD4+ lymphocyte counts determined via the conventional method of combining a flow cytometry-derived percentage with a hematology instrument-derived lymphocyte count. There was no significant difference (P = .388) in CD3+/CD4+ lymphocyte percent determinations between the CytoronAbsolute and the FACScan or Profile II flow cytometers used in this study. These results demonstrate that different operators can cross calibrate CytoronAbsolutes for absolute CD3+/CD4+ lymphocyte subset determinations, even over large geographic distances.

Effective communication using a speech aid for a postlaryngectomy patient undergoing regional anesthesia: a case report

A 73-year-old postlaryngectomy male with a tracheostomy was admitted for bladder biopsy and right retrograde pyelogram. At the preoperative visit, the patient was able to communicate effectively only after the suggestion was made to use his speech aid. The patient was asked to bring his Servox Inton electrolarynx to the operating room. The patient received a spinal anesthetic. Adequate communication during the 150-minute procedure was maintained using his speech aid. Postlaryngectomy voicelessness is a cause of psychological trauma in the postlaryngectomy patient. Different techniques have been proposed for producing sounds. An artificial larynx can be used for the postlaryngectomy patient while, or instead of, learning other types of speech. To prevent the possibility of electrical shock while using a metal encased electrolarynx in conjunction with an electrosurgical unit, we recommend removing the metal housing. When intubating a patient with a speech prosthesis in a surgically created tracheoesophageal puncture, we suggest removing the prosthesis and stenting the tracheoesophageal puncture with a catheter. This will prevent both disloding of the speech prosthesis and closure of the fistula. It is important for the anesthetist to become familiar with speech aids in order to establish effective communication with postlaryngectomy patients.

Regulation of ANP secretion by endothelin-1 in cultured atrial myocytes: desensitization and receptor subtype

We examined endothelin-1 (ET-1) binding and ET-1-regulated atrial natriuretic peptide (ANP) secretion in primary cultures of adult rat atrial myocytes. ET-1 binding was analyzed as a reversible bimolecular reaction, with bimolecular association rate constant = 1.9 x 10(9) M-1.h-1, dissociation rate constant = 0.028 h-1, and a dissociation constant, calculated from these values = 0.015 nM. ET-1 increased ANP secretion with a one-half effective concentration (EC50) of 0.62 nM, which correlated with EC50 receptor occupancy under equivalent experimental conditions (0.75 nM). The secretory response rapidly desensitized (half-time = 10 min at 10 nM ET-1). The time courses for ET-1 binding, ET-1-stimulated secretion, and desensitization were all comparable. Recovery from desensitization was slow and paralleled the recovery of 125I-labeled ET-1 binding. The ETA receptor subtype-selective antagonist, BQ-123, inhibited 125I-ET-1 binding and ET-1-activated ANP secretion with high affinity, whereas the ETB-selective agonists, endothelin-3 and sarafotoxin S6c, inhibited binding with low affinity and did not effectively stimulate ANP secretion. We conclude that 1) ET-1 can stimulate ANP secretion by direct action on the atrial myocytes; 2) primary cultures of adult rat atrial myocytes express only the ETA receptor subtype; 3) the ANP secretory response to ET-1 desensitizes rapidly but recovers slowly; and 4) occupation of the ETA receptors by ET-1 initiates the unidirectional sequence of receptor activation, signal transduction, ANP secretion, and finally, desensitization.

Localization of atrial natriuretic peptide in caveolae of in situ atrial myocytes

The plasma membrane-associated non-clathrin-coated vesicles called caveolae are multifunctional organelles thought to be implicated in the sequestration and transport of small molecules (potocytosis) as well as in the binding of Ca2+ ions, signal transduction, and processing of hormonal and mechanosensitive signals. We have previously suggested that the apparent contiguity of caveolar and atrial granule membranes observed in electron micrographs of in situ mouse atrial myocytes might reflect externalization of atrial natriuretic peptide through caveolae. Using Tokuyasu's classic technique, we now show by immunoelectron microscopy of glutaraldehyde-fixed and cryosectioned mouse and rat atria that antibody against atrial natriuretic peptide prohormone is present within caveolae of in situ atrial myocytes. We confirm this intracaveolar localization by stereoimaging colloidal gold-labeled antibody to the prohormone in electron micrographs of glutaraldehyde/osmium tetroxide-fixed positively stained atrial thin sections. Because profiles of caveolae were rarely immunolabeled with antibody against atrial peptide unless there was a profile of an immunolabeled atrial granule nearby in the subjacent cytoplasm, we concluded that the intracaveolar hormone was derived predominantly from a direct interaction of atrial granules with caveolae. Perturbations that markedly increase the rate of natriuretic peptide secretion via the regulated pathway, including atrial stretch, contractions, and increased external Ca2+ concentration, failed to alter caveolar immunostaining. These results suggest that atrial peptide can pass from atrial granules into caveolae by transiently open pathways between the interiors of granules and caveolae. The results are interpreted as suggesting the presence of a second pathway for externalization of atrial natriuretic peptide through caveolae in addition to the classic pathway for regulated atrial peptide secretion at noncaveolar plasmalemma.

Comparison of treadmill and bicycle exercise in patients with chronic heart failure

The general opinion that treadmill exercise elicits circulatory reserve more than bicycle exercise derives from studies conducted in normal subjects or subjects with coronary artery disease. To investigate if this also occurs in patients with chronic heart failure (CHF), 40 patients (mean ejection fraction: 26 +/- 9 percent) with normal pulmonary function underwent in random order both treadmill (Naughton modified protocol, holding on handrails permitted) and bicycle (10 W/min) maximal exercise over a 1-week period. Peak oxygen uptake (19.6 +/- 5.3 vs 17.6 +/- 5.1 ml/min/kg, p < 0.0001), ventilatory threshold (14.4 +/- 4.7 vs 12.0 +/- 3.5 ml/min/kg, p < 0.0001), and minute ventilation (59 +/- 18 vs 55 +/- 15 L/min, p < 0.05) were greater on treadmill than on bicycle. Heart rate, systolic blood pressure, breathing rate, respiratory exchange ratio, perceived exertion scale, and lactate were identical. The coefficient of the correlation between oxygen uptake and time was greater with bicycle than with treadmill (r = 0.97 +/- 0.04 vs 0.90 +/- 0.07, p < 0.001). Thus, treadmill exercise is more suitable for determining peak oxygen uptake in patients with CHF. However, the increase in oxygen uptake is more regular with bicycle exercise.

Comparison of dosage-dependent effects of beta-aminopropionitrile, sodium fluoride, and hydrocortisone on selected physical properties of cortical bone

BAPN, sodium fluoride, and hydrocortisone are reported to induce altered mineralization states. Three separate sets of experiments, one set for each agent, were performed using male New Zealand white rabbits. In each experiment the rabbits were segregated into groups, each fed a specified weight-determined dose for 13 weeks and then sacrificed. Compact bone from the left femur and tibia were tested for density, composition, sonic velocity, longitudinal elastic modulus, equatorial diffraction spacing of mineralized collagen, diaphyseal cross-sectional area, and relative load stress. beta-Aminopropionitrile (BAPN) induced monotonic degradation of all properties at all dose levels, corresponding to the decreasing density with dosage level. The elastic moduli show a decrease; the equatorial diffraction spacing of the collagen increases. The cross-sectioned diaphysis resembled woven bone. The variability in properties increased with dosage. The total cross-sectional area for a given weight increased, implying that the decreased elastic properties were compensated for by a larger area to support the weight. There was a slight increase in average density and other properties for fluoride-treated rabbits, peaking at 20 mg/kg BW/day. For higher dosages the properties are degraded and the values were much lower at high fluoride dosages than for BAPN. There was no peak for the equatorial diffraction spacing, which increased with dosage. It is inferred that the fluorosed apatite is denser than normal apatitic mineral and therefore has a smaller specific volume. A greater weight fraction of fluorosed mineral has a smaller volume fraction than the equivalent normal apatitic mineral. The bone sections look more normal, except for the porosis. The total cross-sectional area decreases when the bone density increases and then increases as the density falls, again implying that the area required to support body weight depends on the magnitude of the elastic moduli. There was a small change in some of the properties of the bones of the hydrocortisone-treated rabbits, but the effects on others were undetectable within the uncertainty of the procedures. There was no change in the cross-sectional areas of the diaphyses.

Endocytosis and uptake of lucifer yellow by cultured atrial myocytes and isolated intact atria from adult rats. Regulation and subcellular localization

The time course of endocytic uptake of Lucifer yellow (LY) was followed by fluorescence and electron microscopy after exposure of primary cultures of atrial myocytes from adult rats to LY under conditions that prevented transplasmalemmal LY entry via channels or carriers. After a 2-minute exposure to LY at 37 degrees C, electron microscopy revealed classic clathrin-coated vesicles fused to endosomes, which were absent in LY-free medium or at 2 degrees C, suggesting that LY turns on endocytosis or accelerates a slow constitutive endocytosis. Fluorescence microscopy, which detected no LY entry at 2 minutes in LY, showed punctate cytoplasmic fluorescent densities after 10 minutes, which were readily distinguishable from intrinsic perinuclear fluorescence. Fluorescence microscopy after immunostaining with antibodies against clathrin, vacuolar H(+)-ATPase, atrial peptide, or a marker for acidified compartments suggested LY sorting into an acidified prelysosomal pathway. Using absence of punctate fluorescence after 10 minutes in LY as a criterion for inhibition of endocytosis, we showed that endocytosis was inhibited by inhibitors of protein phosphatases 1 and 2A or inhibitors of cAMP-dependent protein kinases 1 and 2, by effects of caffeine on sarcoplasmic reticulum Ca2+ release, and by temperatures below 18 degrees C, but not by staurosporine, phorbol esters, pertussis toxin, thapsigargin, preventing contractions with nifedipine, ryanodine and low [Ca2+]o, or raising cytosolic cAMP concentrations. Both phosphatase inhibitors and caffeine also inhibited a fraction of LY uptake by intact rat atria. We conclude that endocytic uptake of LY is an energy-dependent, specifically regulated process, whose understanding and control are potentially important for the medically relevant problem of introducing drugs and macromolecules into atrial heart muscle cells.

[Rehabilitation of patients with chronic cardiac insufficiency. Immediate and midterm effects]

OBJECTIVES

While physical training is known to improve cardiac performance in patients with chronic congestive heart failure, we conducted this study to evaluate the effect of such training programmes.

METHODS

The study group included 48 untrained patients with stable chronic heart failure controlled with the same daily oral regimen including 0.25 mg digitoxin, 40 mg furosemide and 50 mg captopril. Halt of the patients (n = 24) entered a physical rehabilitation programme for a 3-week period. Each daily session included passive mobilization of the limbs (10 min), respiratory exercises (10 min) and endurance exercise on an ergometric cycle with a maximum work load of 50, 60 and 70% of the theoretical maximal load for weeks 1, 2 and 3 respectively. The other 24 patients did not change their physical activity level and served as controls. The immediate and medium term effects (3 months after the end of the training programme) were assessed using exercise tests, left ventricular isotopic ejection fraction and plethysmography of the lower limbs. The quality of life was compared using the NYHA functional classification and the Goldsman questionnaire.

RESULTS

At the end of the 3-week training period, and compared with the control group, there was a moderate improvement of VO2max (p < 0.02) and a 10% improvement in the ejection fraction (p < 0.05) in the trained patients. There was a clearly significant improvement in the anaerobic threshold and arterial blood flow rate (p < 0.001) and lowered vascular resistance (p < 0.001) and venous tone (p < 0.001). The quality of life was also improved in the training group. However, 3 weeks after the end of the training period, these differences disappeared.

CONCLUSION

Patients with chronic heart failure can benefit from physical training showing functional improvement and no deleterious effect on left ventricular function. This beneficial effect is nonetheless temporary and would appear to be due to improved skeletal muscle oxidative capacity and peripheral haemodynamics.

Fluid-phase endocytosis by in situ cardiac myocytes of rat atria

Fluid-phase endocytosis (FPE) associated with recycling of fused plasmalemma-secretory granules or membranes and/or membrane receptors by in situ cardiac myocytes was studied at 37 degrees C in vitro noncontracting adult rat atrial preparations. Measurements included 1) the volume (VS*) of the compartment consisting of presumptive endocytotic vesicles and the endosomes or lysosomes transiently in continuity with them (S*), which internalizes [14C]-sucrose but is inaccessible to simultaneously measured [methoxy-3H]inulin, 2) the kinetics of [14C]sucrose efflux from S*, and 3) morphometry to quantify interstitial space and non-heart muscle cells. Vs* (0.39 +/- 0.04 ml/g dry atrium for unstretched atria at 37 degrees C) was 1) variable over a 3.7-fold range under various experimental conditions, 2) significantly increased by neomycin or by lowering the temperature to 18 degrees C, and 3) significantly decreased by alpha 1-adrenergic stimulation. Analysis of sucrose efflux kinetics confirmed the presence of an intramyocytic sucrose-containing compartment. A smaller inulin-inaccessible sucrose space (S*) was also present in right ventricle. Thus, during FPE, vesicles and endosomes initially containing high (extracellular) Ca2+ and Cl- concentrations continually enter, circulate within, and undergo exocytosis from myocardial cells.

Rat atrial myocyte plasmalemmal caveolae in situ. Reversible experimental increases in caveolar size and in surface density of caveolar necks

The structure, size, and surface density of the conspicuous flask-shaped structures called caveolae that are located under the plasma membrane of cardiac myocytes in intact rat atria were studied by electron microscopy after physiological perturbations designed to examine whether caveolae and/or their necks are fixed or mobile and whether the caveolar lumen is always open or can close off from the interstitial space. We showed that, in stretched and unstretched atria, horseradish peroxidase could enter or be washed out of caveolae at 37 degrees, 18 degrees, and 4 degrees C, but this finding does not rule out that caveolae and/or their necks can cycle rapidly between states closed and open to the interstitial space. Electron microscopy of thin sections revealed that exposure of atria at 37 degrees or 18 degrees C to physiological salt solutions made hypertonic by adding 150 mM sucrose or mannitol resulted in a striking enlargement of caveolar profiles within 1 to 5 minutes. Caveolar enlargement was rapidly reversible on return to control saline. After freeze fracture of atria exposed to these hypertonic solutions, quantitative analysis of electron micrographs of the fracture faces revealed statistically significant increases in cross-sectional diameter of cross-fractured caveolar necks and in mean number of caveolar necks penetrating per unit area of plasmalemmal fracture face. These results suggest that atrial myocyte caveolae are dynamic structures whose necks may be reversibly inserted into and withdrawn from the plasmalemma, possibly (but not necessarily) corresponding to states in which caveolae are, respectively, open and closed to the interstitial spaces.

[Cardiorespiratory and metabolic changes during prolonged exercise at 50% of the maximal load. Application to rehabilitation of severe cardiac insufficiencies]

The object of physical training in patients with chronic cardiac failure and severe left ventricular dysfunction is to improve skeletal muscle adaptation without impairing myocardial function. It is acknowledged that aerobic exercise limits increased ventricular strain. Therefore, the authors decided to determine whether exercise at 50% maximal power load constituted aerobic training. Eight patients with chronic cardiac failure (age 57 +/- 10 years; resting radionuclide ejection fraction: 25 +/- 5%) performed a rectangular submaximal exercise for 20 minutes at 50% of maximal aerobic load (MAL) as determined by a prior triangular exercise test at 10 W/mn (MAL = 92 +/- 26 Watts-Peak VO2 = 14.8 +/- 2.4 ml/Kg/mn). Gaseous exchanges (VO2, VCO2) minute volume (MV) and serum lactates were measured at rest and every 5 minutes during exercise. MV, VO2 and VCO2 increased significantly (p < 0.005) with a change of less than 5% between the 20th and 10th minute. Respiratory quotient was unchanged until the end of exercise and serum lactate levels stabilised between the 10th (3.4 +/- 0.66 mmol/l) and the 20th minute of exercise (3.5 +/- 0.47 mmol/l). No significant relationship was observed between ventilation and serum lactate or between respiratory quotient and serum lactate. These results confirm that exercise at 50% of maximal load is aerobic training even in patients with severe left ventricular dysfunction. This parameter would appear to be more useful than using the heart rate which is often abnormal in chronic cardiac failure (abnormal chronotropic response, atrial or ventricular arrhythmias).