[Secondary prevention of osteoporosis and identification of high risk patients]

Low bone mass is a major determinant of bone fragility. With respect to hip fracture risk however, there is limited contribution of BMD to the exponential age-related increase in hip fracture incidence. Large prospective studies have identified a number of additional risk factors for hip fractures independent of bone density. These can be classified as skeletal factors and fall-related factors. Body height and hip axis length are positively correlated with fracture risk. Neuromuscular impairment with low gait speed, difficulty in doing a tandem walk, lower limb dysfunction, body sway or inability to rise from a chair without using one's arms predict future fracture risk. According to the concept of evidence-based medicine (EBM) preventive strategies are now available. Supplementation with calcium and vitamin D restores bone quality through suppression of secondary hyperparathyroidism and decreases the risk of falling through improvement of neuromuscular co-ordination and body sway. Treatment with the bisphosphonates alendronate and risedronate increase bone strength and result in a significant reduction of vertebral as well as non-vertebral fractures. Hip protectors absorb energy during a fall and reduce hip fracture risk by 56%. Risk factor based patient selection may improve the cost-effectiveness of therapy.

Pumpless extracorporeal lung assist and adult respiratory distress syndrome

We report use of a pumpless extracorporeal lung assist-a safe and effective method in the management of severe acute respiratory failure that allows an extracorporal gas-exchange without the use of a pump.

Effects of a short-term vitamin D and calcium supplementation on body sway and secondary hyperparathyroidism in elderly women

Long-term vitamin D and calcium supplementation is effective in reducing nonvertebral fractures in elderly people. Increased bone fragility caused by secondary hyperparathyroidism (sHPT) and impaired balance are known risk factors for hip fractures. The hypothesis is that short-term therapy with calcium and vitamin D may improve body sway as well as sHPT more effectively than calcium monotherapy. The effects of 8 weeks of supplementation with vitamin D (cholecalciferol) and calcium on body sway and biochemical measures of bone metabolism were measured. The sample consisted of 148 women (mean [+/-SD] age, 74 +/- 1 years) with a 25-hydroxycholecalciferol level below 50 nmol/liter. They received either 1200 mg of calcium plus 800 IU of vitamin D or 1200 mg of calcium per day. We measured intact parathyroid hormone (PTH), markers of bone turnover, and body sway before and after treatment. Falls and fractures among the participants were followed over a 1-year period. Compared with calcium mono, supplementation with vitamin D and calcium resulted in an increase in serum 25-hydroxyvitamin D of 72% (p < 0.0001), a decrease in the serum PTH of 18% ( p = 0.0432), and a decrease in body sway of 9% (p = 0.0435). The mean number of falls per subject during a 1-year follow-up period was 0.45 for the calcium mono group and 0.24 for the calcium and vitamin D group (p = 0.0346). Short-term supplementation with vitamin D and calcium improves sHPT and body sway and therefore may prevent falls and subsequent nonvertebral fractures in elderly women.

Jamming and fluctuations in granular drag

We investigate the dynamic evolution of jamming in granular media through fluctuations in the granular drag force. The successive collapse and formation of jammed states give a stick-slip nature to the fluctuations which is independent of the contact surface between the grains and the dragged object, thus implying that the stress-induced collapse is nucleated in the bulk of the granular sample. We also find that while the fluctuations are periodic at small depths, they become "stepped" at large depths, a transition which we interpret as a consequence of the long-range nature of the force chains.

Pumpless extracorporeal lung assist - experience with the first 20 cases

OBJECTIVE

Long-term extracorporeal lung assist is limited by a significant mechanical blood trauma resulting in bleeding and hemolysis. To reduce the drawbacks of extracorporeal lung assist a new technique has been developed, by which the driving force for the extracorporeal circuit derives from the patients arterio-venous pressure gradient (pumpless extracorporeal lung assist). The aim of this clinical study was to test the feasibilty and effectiveness of pumpless extracorporeal lung assist in patients with acute respiratory distress syndrome.

METHODS

Twenty patients (41+/-16 years) with acute respiratory distress syndrome of various causes and failing respirator therapy were enrolled. The minimum hemodynamic requirements included a cardiac output (CO) >6 l/min and mean arterial pressure (MAP) >70 mmHg. Pumpless extracorporeal lung assist was established using a short circuit arterio-venous shunt including a special designed low-resistance membrane oxygenator which was placed between the patients legs.

RESULTS

At the time of inclusion FiO(2) in all patients was 1.0 (paO(2) 45.9+/-7 mmHg, paCO(2) 58.9+/-17 mmHg). After 24 h of pumpless extracorporeal lung assist FiO(2) was reduced to 0.8+/-0.1. A significant improvement in oxygenation (paO(2) 84.1+/-21 mmHg, P<0.05) and CO(2) removal (paCO(2) 32.7+/-5 mmHg, P<0.05) was notable. The mean extracorporeal flow was 2.6+/-0.6 l/min, which represented approximately 25% of the patients mean CO (10.8+/-2 l/min). The median assist time was 12+/-8 (1-32) days. Fifteen out of twenty patients were weaned off pumpless extracorporeal lung assist. Five out of twenty patients died while on the system (four sepsis, one ventricular fibrillation). Three out of twenty patients died after successful weaning on day 8, 30, and 50, respectively. Twelve out of twenty patients were discharged in a healthy state (overall survival 60%). Technical problems included thrombosis of the venous cannula (n=5), thrombus formation within the membrane oxygenator (n=2), membrane oxygenator plasma leakage (n=2), and membrane oxygenator contamination with Candida albicans. No bleeding complication was observed.

CONCLUSION

Pumpless extracorporeal lung assist is feasible and effective in a selected group of patients with acute respiratory distress syndrome but preserved hemodynamic function. By eliminating the pump and reducing the tubing length blood trauma can be minimized. Being very simple the system entails fewer risks of technical complications and also facilitates nursing care.

Decreased cortisol secretion by adrenal glands perfused with the P-glycoprotein inhibitor valspodar and mitotane or doxorubicin

The aim of this study was to investigate the role of P-glycoprotein (P-gp) in the adrenal gland. It has been presumed that P-gp, rather than being involved in physiological cortisol secretion, plays a role in protecting the adrenacortical cells from xenobiotics. To explore this a study was performed on perfused bovine adrenal glands. Individual experimental groups were perfused with either a selective P-gp blocker (valspodar) alone, with a xenobiotic (mitotane or doxorubicin) alone or with both valspodar and a xenobiotic. The cumulative amounts of cortisol secreted in each individual group were calculated and the two-sample t-test was used to compare the mean values of cumulative amounts. The mean value of cortisol secreted from the group of adrenals perfused with the P-gp blocker was not significantly different from that of the control group. Treatment with either mitotane or doxorubicin decreased the amount of cortisol secreted but not significantly when compared to the amount of cortisol secreted in basal conditions. However, treatment with the P-gp blocker valspodar in addition to either mitotane or doxorubicin significantly decreased cortisol secreted compared to the amount of cortisol secreted by the glands treated with either mitotane (p=0.009) or doxorubicin (p=0.017) alone. The regressive changes discovered in all experimental groups were most prominent when valspodar was used with either mitotane or doxorubicin. We found that P-gp blockade increases by xenobiotic (mitotane and doxorubicin)-induced damage of adrenocortical cells, which points to a role of P-gp in the protection of adrenal gland from xenobiotics.

Effects of chronic hypoxia on renal renin gene expression in rats

BACKGROUND

The effects of hypoxia on renin secretion and renin gene expression have been controversial. In recent studies, we have demonstrated that acute hypoxia of 6 h duration caused a marked stimulation of renin secretion and renal renin gene expression. This hypoxia-induced stimulation of the renin-angiotensin system might contribute, for example, to the progression of chronic renal failure and to the development of hypertension in the sleep-apnoea syndrome. For this reason, we were interested in the more chronic effects of hypoxia on renal renin gene expression and its possible regulation.

METHODS

Male rats were exposed to chronic normobaric hypoxia (10% O(2)) for 2 and 4 weeks. Additional groups of rats were treated with an endothelin ET(A) receptor antagonist, LU135252, or a NO donor, molsidomine, respectively. Systolic blood pressure and right ventricular pressures were measured. Renal renin, endothelin-1 and endothelin-3 gene expression were quantitated using RNAase protection assays.

RESULTS

During chronic hypoxia, haematocrit increased to 72+/-2%, and right ventricular pressure increased by a mean of 26 mmHg. Renal renin gene expression was halved during 4 weeks of chronic hypoxia. This decrease was reversed by endothelin receptor blockade (105 or 140% of baseline values after treatment for weeks 3-4 or 1-4). Furthermore, there was a trend of increasing renal endothelin-1 gene expression (to 173% of baseline values) after 4 weeks of hypoxia. Systolic blood pressure increased moderately during 4 weeks of chronic hypoxia from 129+/-2 to 150+/-4 mmHg. This blood pressure increase was higher in rats treated for 4 weeks with an endothelin receptor antagonist (196+/-11 mmHg).

CONCLUSIONS

Chronic hypoxia (in contrast to acute hypoxia) suppresses renal renin gene expression. This inhibition presumably is mediated by endothelins.

Oral contraceptive usage and the expression of CA 15-3 and c-erbB-2 in the saliva of healthy women

OBJECTIVE

This study was conducted to determine if oral contraceptive use affected the salivary levels of 2 cancer biomarkers, cancer antigen 15-3 (CA 15-3), and c-erbB-2 (erb) among women.

STUDY DESIGN

A total of 40 women were recruited for this study, 20 controls and 20 using oral contraceptives. The average ages were 27.4 years (control) and 27.1 years (using estrogen supplements). Stimulated whole saliva specimens were collected from each woman. CA 15-3 levels were determined using enzyme immunoassay (EIA) while c-erbB-2 levels were determined by standard ELISA methods.

RESULTS

Findings from this study indicate that there were no significant differences between the control and study groups.

CONCLUSIONS

Therefore, saliva may be a useful tool for monitoring women with high estrogen levels due to either tumor load or any treatment regimen, i.e., the levels of the cancer biomarkers CA 15-3 and erb are not affected by increased levels of estrogen in the body.

CA 15-3 and c-erbB-2 presence in the saliva of women

Two markers used to aid in the diagnosis and treatment of breast cancer were examined in the saliva of a cohort of 135 healthy women. The investigators detected the presence of cancer antigen 15-3 (CA 15-3) and c-erbB-2 in the saliva sampled from the 135 women. The marker concentrations for CA 15-3 and c-erbB-2 were also evaluated and compared in terms of tobacco usage, menopausal status, estrogen usage, systemic diseases, prescription medications, race, and age. The results of the study showed no association between the aforementioned variables and salivary marker concentrations. The results of this study establish a baseline for measuring the biomarkers in the saliva of women with no evidence of malignant disease and add further support to the notion that salivary concentrations of CA 15-3 and c-erbB-2 may be useful in the detection of breast cancer and/or the post operative follow-up of patients being treated for carcinoma of the breast.

Urokinase-type plasminogen activator binding to its receptor stimulates tumor cell migration by enhancing integrin-mediated signal transduction

Urokinase-type plasminogen activator (uPA) and its receptor (uPAR) participate in matrix degradation and cell migration by focusing proteolysis and functioning as a signaling ligand/receptor complex. uPAR, anchored by a lipid moiety in the membrane, is thought to require a transmembrane adapter to transduce signals into the cytoplasm. To study uPAR signaling, we transfected the prostate carcinoma cell line LNCaP, which does not express endogenous uPA or uPAR, with a uPAR encoding cDNA, resulting in high-level surface expression. We studied migration of these cells on fibronectin, which is mediated by the integrin alpha5beta1. Ligation of uPAR with uPA or its amino-terminal fragment enhanced haptotactic migration to fibronectin. In cells on fibronectin, but not on poly-l-lysine, ligation of uPAR also resulted in tyrosine phosphorylation of several proteins, including two proteins involved in integrin signaling, focal adhesion kinase and the crk-associated substrate p130(Cas). Furthermore, after uPAR ligation, uPAR was co-immunoprecipitated with beta1 integrins from the detergent-insoluble fraction of cell lysates. Thus, our data suggest that uPAR occupancy results in an interaction between uPAR and integrins and a potentiation of integrin-mediated signaling, which leads to enhanced cell migration.

Hemodynamic changes and neurohumoral regulation during development of congestive heart failure in a model of epinephrine-induced cardiomyopathy in conscious rabbits

BACKGROUND

The present study was designed to study the progression of heart failure in rabbits with catecholamine-induced cardiomyopathy.

METHODS AND RESULTS

We investigated the effects of three repetitive applications (at 16-day intervals) of high-dose epinephrine (first infusion, 5 micrograms/kg/min for 60 minutes; second and third infusions, 4 micrograms/kg/min for 60 minutes) on hemodynamics, echocardiographic parameters, and plasma hormone levels in eight conscious rabbits chronically instrumented with a Doppler flow probe around the proximal abdominal aorta and a catheter in the right atrium. Mean arterial pressure and blood flow velocity, as well as the acceleration of blood flow velocity (df/dt) in the proximal abdominal aorta were progressively reduced, and right atrial pressure was significantly elevated. On echocardiography, progressive left ventricular (LV) dilatation with depressed LV systolic function and an increase in LV mass were observed. Plasma atrial natriuretic peptide level was enhanced approximately fourfold after each epinephrine infusion, with a tendency to return to baseline values. Plasma renin activity (PRA) was increased after the first epinephrine application (3.0 +/- 0.5 to 6.4 +/- 0.9 ng angiotensin I (AI)/mL/h; P < .05), followed by a return to control levels. After the second epinephrine infusion, a significant decrease to 1.0 +/- 0.3 ng AI/mL/h (P < .05) was observed. After the third catecholamine treatment, PRA levels insignificantly increased. Plasma vasopressin level significantly increased from 0.5 +/- 0.2 to 1.1 +/- 0.5 pg/mL (P < .05) after the second epinephrine infusion.

CONCLUSION

Repetitive infusions of high doses of epinephrine induce a cardiomyopathy with progressive hemodynamic deterioration, LV dilatation and hypertrophy, depressed systolic function, and different stages of neurohumoral compensation. This model appears to be suitable to study the progression of chronic heart failure by serial measurements in a small animal preparation.

Growth hormone (GH) and atherosclerosis: changes in morphology and function of major arteries during GH treatment

Patients with hypopituitarism have increased carotid artery intima-media thickness and reduced arterial distensibility. The effect of 2 years of growth hormone (GH) replacement therapy on these parameters was studied in 11 GH-deficient men (age range, 24-49 years) with hypopituitarism and compared with 12 healthy, age-matched men with no evidence of pituitary or vascular disease. Before treatment the intima-media of the common carotid arteries and the carotid bifurcations were significantly thicker in patients (P < 0.001) than in the control group. Treatment with GH normalized the intima-media thickness of the common carotid artery within 6 months and of the carotid bifurcation within 3 months. The changes in intima-media thickness of the carotid artery were negatively correlated with changes in serum levels of insulin-like growth factor I during treatment. There was a significant improvement in flow-mediated, endothelium-dependent dilation of the brachial artery at 3 months, which was sustained at 6, 18 and 24 months of GH treatment (P < 0.05). Thus, GH replacement therapy in GH-deficient men reverses early morphological and functional atherosclerotic changes in major arteries, and may reduce rates of vascular morbidity and mortality.

Growth hormone (GH) treatment reverses early atherosclerotic changes in GH-deficient adults

Hypopituitary patients have increased mortality from vascular disease, and in these patients, early markers of atherosclerosis [increased carotid artery intima-media thickness (IMT) and reduced distensibility] are more prevalent. As GH replacement can reverse some risk factors of atherosclerosis, the present study examined the effect of GH treatment on morphological and functional changes in the carotid and brachial arteries of GH-deficient (GHD) adults. Eleven GHD hypopituitary men (24-49 yr old) were treated with recombinant human GH (0.018 U/kg BW x day) for 18 months. IMT of the common carotid artery (CCA) and the carotid bifurcation (CB), and flow-mediated endothelium-dependent dilation (EDD) of the brachial artery were measured by B mode ultrasound before and at 3, 6, 12, and 18 months of treatment, and values were compared with those in 12 age-matched control men. Serum concentrations of lipids, lipoprotein(a), insulin-like growth factor I (IGF-I), and IGF-binding protein-3 (IGFBP-3) were also measured. In GHD men before treatment the IMTs of the CCA [mean(SD), 0.67(0.05) mm] and CB [0.75(0.04) mm] were significantly greater (P < 0.001) than those in control men [0.52(0.07) and 0.65(0.07) mm, respectively]. GH treatment normalized the IMT of the CCA by 6 months [0.53(0.04) mm] and that of the CB by 3 months [0.68(0.05) mm]. The IMT of the carotid artery (CCA and CB) was negatively correlated with serum IGF-I (r = -0.53; P < 0.0001). There was a significant improvement in flow-mediated EDD of the brachial artery at 3 months, which was sustained at 6 and 18 months of GH treatment (P < 0.05). GH treatment increased high density lipoprotein cholesterol at 3 and 6 months, but did not reduce total or low density lipoprotein cholesterol and was without effect on lipoprotein(a). There was no correlation between plasma lipids and changes in IMT or EDD of the arteries examined. In conclusion, GH treatment of hypopituitary GHD men reverses early morphological and functional atherosclerotic changes in major arteries and, if maintained, may reduce vascular morbidity and mortality. GH seems to act via IGF-I, which is known to have important effects on endothelial cell function.

Time since vertebral fracture: an important variable concerning quality of life in patients with postmenopausal osteoporosis

The aim of the study was to identify factors affecting patients with postmenopausal osteoporosis who had experienced one or more vertebral fractures. The overall hypothesis was that time after fracture would influence patients' perception of pain and well-being. The sample (50 patients) was split into two groups (group A, time after fracture < or > 24 months; group B, time after fracture >24 months). A fracture was defined as a vertebral height reduction of more than 20% or at least 4 mm. The assessment was carried out using the Spine Deformity Index and was confirmed by an experienced radiologist. To assess quality of life (QoL) the following measures were used: 'well-being scale' including social extroversion as a subscale, pain scale, and limitations in everyday life. The Sense of Coherence questionnaire developed by Antonovsky measures the ability of a person to see life meaningful, manageable and explicable. This questionnaire may reflect patients' coping abilities and was introduced to establish whether these influence the perception of pain and well-being after vertebral fracture. Variance and covariance analysis was carried out using SPSS (version 6.1). Differences between groups A and B were found for perception of average pain (p = 0.017), social extroversion (p = 0.003) and well-being (p = 0.024). No differences were found for limitations in everyday life (p = 0.607), Sense of Coherence (p = 0.638), the Spine Deformity Index (p = 0.171) and loss of height (p = 0.619). All analyses were corrected for age. Concurrent medication was not found to influence the results. Findings suggest that time after fracture is an important variable when considering QoL and well-being after vertebral fracture and should, therefore, be considered in future studies.

Clinical outcomes of the Otago-Southland Breast Cancer Screening Programme 1991-1996

AIM

To document the clinical outcome of the Otago-Southland Breast Cancer Screening Programme through its first two rounds of screening, from 1991-1996.

METHODS

Review and analysis of clinical and pathological records.

RESULTS

In the first round of screening, 13,876 women were screened, giving 75% uptake; 12.2% were referred for assessment and 126 cancers detected, 9.1 per thousand women screened. For the 9946 incidence screens in the second round, 3.9% of women screened were referred to assessment and 50 cancers detected, 5.0 per thousand women screened. The uptake and cancer detection rates exceed the targets and exceed other published results; the size distribution of the cancers detected was comparable to the Swedish two-counties study, showing that the results should produce an ultimate mortality reduction. The referral rate to assessment was higher than expected in the first round of screening, but within the targeted range in the second round. The benign to malignant ratio for all biopsies was 1.4:1 for the prevalence screen of the first round and 1.2:1 for the incidence screens in the second round, both exceeding the targets set.

CONCLUSIONS

The results show that the uptake and clinical results of the programme exceed expectations and that a large number of small invasive tumours have been successfully detected. These results are comparable to the best of overseas studies, and give confidence that mortality reductions will ultimately occur.

Assessment of left ventricular diastolic filling in arterial hypertension: comparison of pulsed Doppler echocardiography and acoustic quantification

We compared acoustic quantification (AQ) to Doppler echocardiography (DE) in the evaluation of left ventricular (LV) diastolic filling in 41 hypertensives and 42 controls. In hypertensives, DE showed reduced ratios of early to late diastolic velocity, AQ revealed reduced peak to late filling rate ratios, and both techniques found prolonged acceleration times indicating abnormal filling. In 22 patients with mild hypertension and less LV hypertrophy, however, all DE filling parameters were normal. In these patients AQ indicated prolonged acceleration times and early filling times. In conclusion, AQ is useful for the identification of abnormal LV filling in arterial hypertension and might be superior to DE in detection of early diastolic dysfunction.

Quantification of aortic stenosis in mechanically ventilated patients using multiplane transesophageal Doppler echocardiography

STUDY OBJECTIVES

To evaluate the feasibility and accuracy of multiplane transesophageal Doppler echocardiographic assessment of the severity of aortic stenosis in mechanically ventilated patients using modified transgastral views of the left ventricular outflow tract and the aortic valve.

DESIGN

A prospective study comparing the results of transesophageal echocardiography (TEE) with transthoracic echocardiography (TTE) and cardiac catheterization.

SETTING

A university hospital.

PATIENTS

Twenty-eight American Society of Anesthesiologists class III and IV patients with aortic stenosis undergoing elective cardiac surgery for valve replacement.

INTERVENTIONS

Intubated and mechanically ventilated patients with aortic stenosis undergoing cardiac surgery for valve replacement were studied by multiplane transesophageal Doppler echocardiography to determine transvalvular pressure gradients (Bernoulli formula) and valve areas (continuity equation). These findings were compared with the respective preoperative data from TTE and cardiac catheterization.

MEASUREMENTS AND RESULTS

In 25 of 28 patients (89%), adequate transgastral Doppler recordings of the aortic jet could be obtained. The TEE measurements correlated well with the respective data obtained by TTE (maximal pressure gradient: r=0.93, p<0.0001, mean difference=5.9+/-5.8 mm Hg [mean+/-SD]; mean pressure gradient: r=0.91, p<0.0001, mean difference=5.4+/-4.6 mm Hg; aortic valve area: r=0.97, p<0.0001, mean difference=0.07+/-0.05 cm2) and cardiac catheterization (n=16) (maximal vs peak-to-peak pressure gradient: r=0.84, p<0.0001, mean difference=10.9+/-8.8 mm Hg; mean pressure gradient: r=0.80, p<0.0002, mean difference=9.7+/-5.9 mm Hg; aortic valve area: r=0.84, p<0.0001, mean difference=0.1+/-0.08 cm2).

CONCLUSION

Multiplane transesophageal Doppler echocardiography offers an alternative approach for assessing the severity of aortic stenosis in mechanically ventilated patients in whom conventional TTE is not feasible.

Effect of the multidrug resistance modulator valspodar on serum cortisol levels in rabbits

PURPOSE

To contribute to a better understanding of the physiological role of P-glycoprotein (P-gp) in the adrenal gland, we initiated our studies in rabbits. The aim of our study was to explore the effect of the selective multidrug resistance (MDR) modulator PSC 833 (valspodar) on serum cortisol in rabbits.

METHODS

Baseline and corticotropin-stimulated serum cortisol levels were measured before and after valspodar treatment in adult male rabbits. Seven rabbits were treated with 50 mg/kg per dose and seven, with 75 mg/kg per dose of valspodar subcutaneously. Serum cortisol levels were determined by radioimmunoassay adjusted for expected values.

RESULTS

Serum cortisol levels (baseline as well as corticotropin-stimulated) increased after both valspodar treatment regimens. The increase was dose-dependent and was higher for the baseline than for the corticotropin-stimulated values. Serum valspodar levels exceeding 1000 ng/ml were achieved in all except one animal in each group. We hypothesize that the increased serum cortisol levels were due to increased adrenocorticotropic hormone (ACTH) secretion after valspodar treatment, but, unfortunately, we could not measure ACTH properly in rabbits by means of the commercially available kits.

CONCLUSIONS

Our study indicates that P-gp is not involved in steroid hormone secretion in the adrenal gland. This is evident from observations that serum cortisol levels were found to have increased rather than decreased in rabbits treated with a P-gp blocker and that the treated animals appeared healthy and normal. Since P-gp was found to play an important role in protection against xenobiotics in some other organs, further studies to explore the protective role of P-gp in the adrenal gland are warranted.

Reciprocal regulation of pulmonary and cardiac angiotensin-converting enzyme in rats with severe left ventricular hypertrophy

OBJECTIVE

Numerous studies support the concept that cardiac angiotensin-converting enzyme (ACE) is involved in the pathophysiology of left ventricular hypertrophy. However, the pulmonary vasculature is considered to be the most prominent site of ACE expression. We thus examined the tissue specificity of ACE regulation in rats with severe cardiac pressure overload hypertrophy in transition to cardiac failure with secondary pulmonary hypertension.

METHODS AND RESULTS

Rats were studied 12 weeks after banding of the ascending aorta (LVH, n = 20) that resulted in a 1.7-fold increase in left ventricular (LV) to body weight ratio. In addition, as compared to sham-operated rats (n = 20), we observed in LVH rats a 1.6-fold increase in right ventricular (RV) to body weight ratio, the development of pulmonary hypertension, and elevated plasma renin activities. Moreover, ACE mRNA and activity levels were more than 2-fold higher in both hypertrophied ventricles (P < 0.01, each). In contrast, pulmonary ACE mRNA and activity levels were markedly decreased in animals with LVH (more than 30%, respectively, P < 0.05 vs. sham), Interestingly, LV and RV ACE activity, as well as systolic pulmonary artery pressure and plasma renin activity, were all inversely related to pulmonary ACE activity. In order to differentiate the potential role of elevated renin in the down-regulation of pulmonary ACE, additional rats (n = 12) were treated with furosemide that resulted in a 8-fold rise in plasma renin activity, but only in a marginal decrease of pulmonary ACE mRNA levels and activity (-10% vs. sham (n = 8), P-value n.s.).

CONCLUSIONS

The data indicate tissue specific reciprocal regulation of pulmonary and cardiac ACE in rats with cardiac pressure overload hypertrophy and pulmonary hypertension, a phenomenon that may potentially result in a partial shift of angiotensin II formation from the pulmonary to the cardiac circulation.

Association of esophageal dysfunction and pulmonary function impairment in systemic sclerosis

OBJECTIVE

The aim of this study was to investigate the relationship between esophageal dysfunction and pulmonary involvement in patients with systemic sclerosis (SSc).

METHODS

Pulmonary function parameters were compared between groups of patients with and without manometric evidence for SSc-induced esophageal dysmotility.

RESULTS

Twenty-six of 43 patients (60.5%) exhibited a marked hypo- or aperistalsis of the smooth muscle portion of the esophagus. Total lung capacity, inspiratory vital capacity, and forced vital capacity were significantly lower in patients with esophageal dysfunction compared with those with normal esophageal peristalsis (p < 0.001). Patients with the diffuse form of SSc (n = 20) had significantly lower values for total lung capacity and inspiratory vital capacity compared with patients with the limited type of SSc (n = 23; p < 0.05).

CONCLUSION

There is a significant association of esophageal dysmotility with reduced lung volumes in SSc. Possible explanations for these findings are pulmonary damage due to increased gastroesophageal reflux and, more likely, simultaneous involvement of the lungs and the esophagus in the disease process.

Vascular remodeling and growth factor gene expression in the rat lung during hypoxia

Recent studies suggest that the vasoactive peptides endothelin-1 and -3 and the mitogens VEGF and PDGF-A and -B could be involved in the pathogenesis of hypoxic pulmonary hypertension. We were interested to investigate whether these peptides could also be involved in the vascular remodeling occurring during chronic hypoxia (10% oxygen; 1 and 3 weeks) in the rat. Hypoxia increased significantly systolic right ventricular pressure and typical morphological signs of vascular remodeling were found. This was accompanied by increased ET-1 and the ET-3 mRNA expression after acute (6 h; P < 0.05) and chronic hypoxia of 1 (P < 0.05) and 3 weeks (P < 0.05). In contrast, we found no effects of hypoxia on the gene expression of VEGF and PDGF-A and -B in the lung. Our findings indicate that ET-3 in addition to ET-1 could be involved in the process of hypoxia-induced vascular remodeling, whereas it appears less likely that the mitogens VEGF and PDGF-A and -B are essentially involved in the pathogenesis of hypoxic pulmonary hypertension.

Development of heart failure following isoproterenol administration in the rat: role of the renin-angiotensin system

OBJECTIVE

High dosages of catecholamines induce cardiomyocyte necrosis and interstitial fibrosis in rats. We investigated whether this initial damage is followed by the development of heart failure and assessed the particular role of the renin-angiotensin system using ramipril.

METHODS AND RESULTS

Following the administration of 0 mg or 150 mg isoproterenol/kg 6 groups of Wistar rats were followed for 2 or 16 weeks: Sham, isoproterenol, isoproterenol + ramipril. Isoproterenol induced significant increases of echocardiographically measured left ventricular end-diastolic posterior wall thickness and dimension, whereas ramipril treatment significantly attenuated these changes. Left ventricular end-diastolic pressure was markedly increased in isoproterenol-treated rats and normalized following ramipril. Isoproterenol rats were further characterized by hormonal activations including transient elevations of plasma renin activity, aldosterone and cardiac angiotensin converting enzyme activity. Histomorphological characterization of isoproterenol-treated hearts demonstrated cardiomyocyte necrosis and reparative fibrosis. Ramipril treatment only slightly reduced the amount of necrosis as well as the expression of extracellular matrix proteins.

CONCLUSIONS

In rats, a toxic dosage of isoproterenol caused characteristic myocardial damage that subsequently resulted in mild heart failure. Ramipril administration following isoproterenol was highly effective to attenuate hemodynamic and hormonal alterations as well as the development of left ventricular hypertrophy, but had only little influence on the expression of extracellular matrix proteins. Since angiotensin converting enzyme inhibition had no impact on the initial myocardial injury, the development of heart failure in this model seems to require functional integrity of the renin-angiotensin system.

Beta-adrenergic stimulation of renin expression in vivo

OBJECTIVE

To characterize the effect of beta-adrenergic activation on renal production of renin in the intact organism.

DESIGN AND METHODS

Renal expression of renin [renin messenger RNA (mRNA)], plasma renin activity (PRA), inactive renin level, intrarenal renin distribution (immunohistochemistry), and the time course of activation of renin as well as hemodynamic parameters were determined during the subcutaneous infusion of isoproterenol (ISO) into rats. To examine whether beta-adrenergic activation of the renin system is modulated by the rate of salt intake rats were fed diets with normal, low and high salt contents.

RESULTS

Systolic blood pressure was not altered. PRA was elevated as much as fourfold after 40 h of ISO infusion. Although renal renin mRNA levels were elevated dose-dependently up to 4.2-fold, no significant recruitment of renin-containing cells could be detected. The time course of PRA revealed a marked transient rise of PRA during 6 h of ISO infusion with a subsequent decline. Inactive renin level was elevated during 3 to 18 h of ISO infusion. In contrast, renin mRNA level increased steadily with a lag phase of 3 h. Infusion of ISO increased PRA and renin mRNA level under a high-salt diet, but had no additional effect either on PRA or on renin mRNA level under low-salt diet.

CONCLUSION

Activation of beta-adrenergic receptors is a powerful stimulus of renin secretion and renin gene expression in juxtaglomerular cells in vivo, albeit the kinetics of upregulation of renin secretion and renin expression are markedly different. Therefore, the sympathetic tone might be a major factor determining the activity of the renin system in vivo. The ability of adrenergic agonists to stimulate the renin system appears to be modulated by the steady-state level of salt intake.

Acute hypoxia upregulates NOS gene expression in rats

This study aimed to investigate the influence of acute tissue hypoxygenation on the expression of NO synthase (NOS) genes in vivo. To this end, male Sprague-Dawley rats were exposed either to 9% oxygen or to 0.1% carbon monoxide for 6 h, and mRNA levels of NOS-I, -II, and -III in kidneys, livers, lungs, and left and right heart ventricles were assayed by ribonuclease protection. For comparison, mRNA levels of erythropoietin were also measured in these tissues. NOS-III mRNA was highly abundant in all organs investigated. NOS-II mRNA was detected in lungs and hearts but not in kidneys and livers. NOS-I mRNA was found in kidneys, lungs, and hearts but not in livers. NOS-III mRNA levels were upregulated by hypoxia in all tissues examined, with the least effect (1.2-fold) in the left ventricle and the greatest effect (2.6-fold) in the lung. NOS-II mRNA was substantially downregulated in the ventricles by both treatments but not changed in the lung. NOS-I mRNA was upregulated by carbon monoxide in kidneys and lungs and by 9% oxygen in the lung. These findings suggest that NOS-III and possibly also NOS-I gene expression behave like oxygen-regulated genes, whereas the general effect of tissue hypoxygenation on NOS-II gene expression is less clear. Because NOS-III is primarily expressed in endothelial cells, a general upregulation of NOS in these cells may be of relevance for the regulation and maintenance of blood flow through hypoxic tissues.

In vivo carbon monoxide exposure and hypoxic hypoxia stimulate immediate early gene expression

This study aimed to examine the influence of acute tissue hypoxygenation on the expression of immediate early genes in different rat tissues. To this end male Sprague-Dawley rats were exposed to 0.1% carbon monoxide for 0.5, 1 and 6 h or to 9% oxygen for 6 h and mRNA levels for c-jun, c-fos, c-myc and EGR-1 were assayed by RNase protection in hearts, kidneys, livers and lungs. We found that hypoxia increased c-jun mRNA levels between twofold (lung) and eightfold (liver) in all organs examined; c-fos mRNA increased between three-fold (lung) and 20-fold (heart); c-myc mRNA increased between twofold (lung) and sixfold (heart); and EGR-1 mRNA increased between twofold (lung) and sixfold (heart). Our findings suggest that acute tissue hypoxygenation is a general stimulus of the expression of immediate early genes in vivo. With regard to the sensitivity to hypoxia, organ differences appear to exist in that the lung is rather insensitive, whilst the heart is rather sensitive.

Evaluation of plasma natriuretic peptides as markers for left ventricular dysfunction

To test the hypothesis that elevated plasma levels of natriuretic peptides may serve to identify patients with left ventricular (LV) dysfunction, we assessed the predictive diagnostic value of natriuretic peptide levels, in addition to clinical and electro-cardiographic risk factors, as noninvasive indicators of cardiac dysfunction. Plasma levels of atrial natriuretic peptide (cANP) (99-126), N-terminal fragment of proANP (nANP) (26-55), nANP(80-96), brain natriuretic peptide (BNP-32), proBNP(22-46), and C-type natriuretic peptide (CNP-22) were measured in 211 subjects before cardiac catheterization. The strongest correlations with parameters of LV function were found for nANP(80-96) (up to r = -0.55, p < 0.0001), whereas there was no significant correlation with proBNP(22-46) or CNP-22. In patients with LV ejection fractions (LVEF) < or = 45% (n = 38) nANP(26-55), nANP(80-96), cANP(99-126), and BNP-32 were significantly increased (p < 0.001). Partition values for elevated versus normal natriuretic peptide levels were obtained from normal controls and used to separate subjects with and without LV dysfunction. Receiver operating characteristic analysis for LVEF < or = 45% indicated a significantly better diagnostic accuracy for high levels of nANP(80-96), nANP(22-56), cANP(99-126), and BNP-32 than for proBNP and CNP-22. Multivariate analysis by logistic regression identified Q waves and bundle branch block in the electrocardiogram as well as elevated plasma levels of cANP, nANP(80-96), and nANP(26-55) as the strongest independent predictors of low ejection fractions. The relative risk of LV dysfunction was raised up to tenfold in subjects with high natriuretic peptide levels (p < 0.001). The addition of nANP(80-96) and nANP(26-55) to the combination of clinical and electrocardiographic risk factors did not further improve the diagnostic sensitivity for the detection of LVEF < or = 45%, but it markedly increased the overall accuracy (59% to 81%, p < 0.001) and specificity (55% to 81%, p < 0.001). Among natriuretic peptides, elevated nANP(80-96) and nANP(26-55) levels have the strongest impact on the detection of LV dysfunction. They add to the diagnostic information contained in clinical and electrocardiographic factors. Plasma levels alone or in combination with clinical factors seem to be of value for a refined identification of abnormal LV function in the individual patient.

Immunohistochemical localization of netrin-1 in the embryonic chick nervous system

Netrin-1 has profound in vitro effects on the growth properties of vertebrate embryonic axons. In addition, netrin-1 mRNA is found in the floor plate of the embryonic nervous system, an intermediate target of many axons, including commissural axons that are affected by netrin-1 in vitro. Moreover, genetic studies of netrin-1 homologs in Caenorhabditis elegans and Drosophila implicate these proteins in commissure formation. We raised polyclonal antisera that recognize chick netrin-1 in fixed tissue sections. The antisera were used to immunohistochemically map netrin-1 in the embryonic spinal cord, brain, and retina. The relationship between netrin-1 localization and the growth of pioneering axons suggests roles for netrin-1 in the regulation of circumferential, commissural, and longitudinal axon growth in the spinal cord and brain. The data also suggest that the primary or sole effect of netrin-1 on pioneering spinal cord commissural axons is haptotactic. Furthermore, the pattern of netrin-1 localization raises the possibility that this protein helps mediate neuronal migration in the spinal cord, brain, and retina.

ANP gene expression in rat hearts during hypoxia

It is unclear whether the increase in plasma atrial natriuretic peptide (ANP) concentration during hypoxia is due to direct, hypoxia-induced upregulation of ANP secretion in the heart, or to pressure overload of the right ventricle (RV) following hypoxia-induced pulmonary hypertension. To test the hypothesis that hypoxia leads to an early upregulation of the ANP gene, we examined the influence of acute and prolonged inspiratory hypoxia (6 h, 1 or 3 weeks) on the expression of ANP messenger ribonucleic acid (mRNA) in rat heart and compared the results with the expression of the ANP gene after acute pressure overload induced by experimental coarctation of the main pulmonary artery. As a molecular marker for hypertrophy we determined the ratio of alpha- and beta-myosin gene expression. Hypoxia increased systolic RV pressure from 20.0 +/- 1.6 mmHg to 27.8 +/- 1.6 mmHg (P < 0.01) and 41.6 +/- 2.1 mmHg (P < 0. 05) after 1 and 3 weeks hypoxia respectively. The ANP plasma concentration did not change significantly after 6 h or 1 week: 232 +/- 21 pg/ml (control), 246 +/- 25 pg/ml (6 h), 268 +/- 25 pg/ml (1 week), but increased significantly after 3 weeks hypoxia (446.8 +/- 99.56 pg/ml; P < 0.05). ANP mRNA levels in different regions of the heart did not change after 6 h or 1 week hypoxia. After 3 weeks hypoxia ANP mRNA had increased 2.7-fold in the RV (P < 0.05), 4. 2-fold in the left ventricle (LV, P < 0.05), 3.5-fold in the septum (S, P < 0.05) and about 1.4-fold in the right (n.s.) and left atrium (n.s.). Relative ventricular masses increased significantly only for the RV (190%, P < 0.05) during hypoxia. The beta/alpha-myosin mRNA ratio did not change after 6 h hypoxia but, contrary to ANP gene expression, increased after just 1 week (6.1-fold in RV, 7.8-fold in LV, 6-fold in S; P < 0.05) and was more pronounced in the RV after 3 weeks (9.4-fold in RV, 7.6-fold in LV, 9.1-fold in S; P < 0.05). The increase in the beta/alpha-myosin mRNA ratio in the LV contrasts with a lack of increase in relative ventricular mass. Acute pressure overload in the RV after pulmonary arterial banding significantly increased ANP-mRNA and the beta/alpha-myosin mRNA ratio after 1 day in the RV. In the LV ANP mRNA was unchanged. The delayed upregulation of the ANP gene suggests that hypoxia per se is not a significant stimulus for ANP gene expression in the heart and that hypoxia-induced ANP-gene expression in the heart is regulated predominantly by the increase in RV afterload due to hypoxia-induced increased pulmonary pressure. The upregulation of ANP and beta-myosin mRNA in the LV during chronic hypoxia has yet to be elucidated.

Transgastric Doppler echocardiographic assessment of the severity of aortic stenosis using multiplane transesophageal echocardiography

We investigated whether multiplane transesophageal Doppler echocardiography using transgastral views allows determination of pressure gadients and valve areas in patients with aortic stenosis. This technique was feasible in 35 of 39 patients (90%), with highly significant correlations with results obtained from transthoracic Doppler echocardiography and cardiac catheterization, thus offering an alternative approach for quantification of aortic stenosis.

Heart rate variability in patients with daytime sleepiness suspected of having sleep apnoea syndrome: a receiver-operating characteristic analysis

1. Periodic breathing is known to be associated with cyclic fluctuations in heart rate. The purpose of this study was to evaluate the capability of spectral analysis of heart rate variability to identify episodes with periodic breathing in patients suspected of having sleep apnoea syndrome. 2. Forty-eight subjects complaining of chronic day-time sleepiness were studied using polysomnography and additional monitoring of Holter-ECG and synchronized pulse oximetry. The recordings were divided into 20 min episodes which were identified as recordings registered during normal breathing, periodic breathing, and periods of both normal and abnormal breathing. Power spectral analysis was performed on episodes which met the criteria of stationary of data (313 episodes with normal breathing, 264 episodes with continuous periodic breathing, 80 episodes with both normal and periodic breathing patterns). 3. The ability of parameters, derived from analysis of heart rate variability, to discriminate between episodes with normal and periodic breathing was assessed by receiver-operating characteristic analysis. 4. The spectral power component in the frequency range 0.01-0.07 Hz revealed the greatest accuracy for discriminating between normal and periodic breathing (area under the receiver-operating characteristic curve = 0.929; standard error = 0.009). The analysis of the episodes classified as false-positive at a given test sensitivity of 90% and a corresponding specificity of 77% revealed that half of these episodes had been recorded during transient central nervous arousal reactions related to periodic leg movements or heavy snoring. 5. We concluded that power spectral analysis of heart rate variability offers a possible means of identifying episodes of sleep-related breathing disorders or periodic leg movements. Therefore, analysis of heart rate variability may be a valuable additional diagnostic tool in patients undergoing Holter-ECG recording.

Ultrasound analyses of the calcaneus predict relative risk of the presence of at least one vertebral fracture and reflect different physical qualities of bone in different regions of the skeleton

Broadband ultrasound attenuation (BUA) and speed of sound (SOS) were determined together with bone mineral density (BMD) of the lumbar spine and of the proximal right hip (QDR 2000, Hologic) in 1252 females (mean age 56 +/- 11). We then calculated the predictive power of BUA and SOS for at least one vertebral fracture and correlation-coefficients of BMD of the spine and hip as well as BUA and SOS in different age groups (SPSS PC + Vers. 2.2. for IBM PC software). The overall prevalence of at least one vertebral fracture was 10.14% (127 out of 1252 patients). The relative risk for the presence of at least one vertebral fracture was 2.7 for BMD spine below 0.7 g Calcium/cm2 (69 out of 249 patients), 1.8 for BMD hip below 0.7 g Calcium/cm2 (106 out of 589 patients), 1.9 for SOS calcaneus below 1500 m/s (99 out of 499 patients) and 1.7 for BUA calcaneus below 110 dB/MHz (103 out of 605 patients). The relative risk for the presence of at least one vertebral fracture increases significantly (p < 0.01). In the age group < 50 the coefficients of correlation were 0.4655 between BMD spine and BUA calcaneus, 0.5259 between BMD spine and SOS calcaneus, 0.4327 between BMD hip and BUA, 0.2760 between BMD hip and SOS. In the age group > 70 the coefficients of correlation were 0.3699 between BMD spine and BUA, 0.3481 between BMD spine and SOS, 0.5946 between BMD hip and BUA, 0.5138 between BMD hip and SOS, respectively. All coefficients of correlation were highly statistically significant (p < 0.001). We conclude that BUA and SOS predict relative risk of the presence of at least one vertebral fracture as well as BMD spine and BMD hip. With increasing age BUA and SOS appear to be an independent predictor, not being inevitably correlated to BMD but possibly reflecting different qualities of bone at different sites of the skeleton.

Cardiovascular autonomic nervous system tests: determination of normative values and effect of confounding variables

OBJECTIVE

To determine normative values for heart rate variation to deep breathing (VAR) and Valsalva ratio (VAL) as well as the effect of various confounding variables on these measures using data from a large group of normal subjects collected from multiple centers.

RESEARCH DESIGN AND METHODS

VAR and VAL were measured on 611 normal subjects, age range 9-79, from 63 centers and was analyzed at a single Autonomic Nervous System Reading Center. Using simple and stepwise logistic regression the effect of age, gender, height, weight, mean arterial blood pressure (MAP) and body mass index (BMI), on VAR and VAL was evaluated.

RESULTS

The 95% normative values range (values at 2.5 to 97.5 percentile) for VAR (n = 580) was 12.8-103.5 (mean 49.7) and for VAL (n = 425) was 1.31-2.97 (mean 1.97). No gender effect was found for either VAR or VAL (p > 0.05). VAR correlated inversely with both age and MAP, while VAL correlated inversely with both age and BMI. Since age is the principal confounding variable for both VAR and VAL, normative values are also presented stratified by age.

CONCLUSION

Normative values for VAR and VAL based on a large population sample are presented. However, the values presented may not be valid in patients with morbid obesity or malignant hypertension. These data are applicable for either individual patients or for use in multicenter research trials.

Leukotriene receptor blockade in experimental heart failure

The pathophysiological role of endogenous leukotrienes in cardiovascular control and the regulation of renal function in congestive heart failure is not known. Therefore, in six conscious dogs with or without heart failure induced by right ventricular pacing (270/min, 10 days) we studied the effects of the leukotriene receptor antagonist FPL55712 on hemodynamics, plasma hormones and renal function. In healthy dogs, FPL55712 (1 mg kg-1 + 0.01 mg kg-1 min-1 i.v.) had little effect on hemodynamics, only reducing heart rate by 11% and insignificantly increasing systemic vascular resistance. Plasma levels of norepinephrine (-57%), renin (-30%) and aldosterone (-24%) were significantly decreased. Renal function parameters were not changed. In dogs with heart failure, FPL55712 significantly increased systemic vascular resistance (+16%) and decreased cardiac output (-15%). Plasma hormone levels were not changed, but renal plasma flow was decreased (-13%) and glomerular filtration rate (+12%), renal vascular resistance (+13%) and filtration fraction (+23%) were increased. It is concluded that there is no evidence for a contribution of endogenous leukotrienes to the systemic vasoconstriction in experimental heart failure. Whether the increase in systemic and renal vascular resistance induced by the leukotriene antagonist in dogs with heart failure reflects a role for endogenous leukotrienes with vasodilator action is still unclear and deserves further investigation.

Catheter-induced pulmonary artery perforation during cardiac surgery: intraoperative surgical management

A case of pulmonary artery rupture due to Swan-Ganz catheterization is reported. A 73-year old women undergoing coronary artery bypass grafting developed massive endotracheal bleeding during weaning from the cardiopulmonary bypass and inflation of the balloon of the Swan-Ganz catheter. As bleeding could not be controlled by endobronchial Fogerty catheter blockade, resection of the lateral segment of the middle lobe was necessary before bypass could be terminated. The postoperative course was complicated by an abscess formation in the right middle lobe of the lung which required operative revision.

Recurrent plantar ulceration following pan metatarsal head resection

Although the pan metatarsal head resection, since it was originally described and performed by Hoffman in 1911, has proven to be an effective and viable procedure in treating many forefoot deformities, it is not without its own complications. The authors provide an historical perspective of the pan metatarsal head resection, a discussion on the complication of recurrent plantar ulceration after the pan metatarsal head resection, and a review of their own experience with this procedure. A retrospective review was performed of all patients having undergone pan metatarsal resections between August 1980 and April 1993. Twenty procedures were performed on 12 patients with diabetic neuropathy, and 21 procedures were performed on 15 patients with rheumatoid arthritis. The incidence of recurrent plantar ulceration after surgical correction was 25% and 28%, respectively. All 27 patients underwent primary healing. The authors, therefore, conclude that the complication of recurrent plantar ulceration after this procedure is a very likely and distinct possibility.

Effects of extreme lateral posture on hemodynamics and plasma atrial natriuretic peptide levels in critically ill patients

OBJECTIVE

To quantify the hemodynamic effects of turning critically ill, mechanically ventilated patients to the extreme left and right lateral postures.

DESIGN

Prospective investigation.

SETTING

Eight-bed intensive care unit in a university hospital.

PATIENTS

Twelve consecutive patients presenting with severe respiratory failure and requiring continuous positive inotropic support.

INTERVENTIONS

All patients were mechanically ventilated and placed in a kinetic treatment system. They were positioned in the supine, left dependent, and right dependent postures, resting for 15 min in each position.

MEASUREMENTS AND RESULTS

Hemodynamic measurements, assessments of right ventricular function, and determinations of intrathoracic blood volume were performed in three different positions. Concentrations of atrial natriuretic peptide in plasma were quantified. In three patients, the findings were controlled by transesophageal echocardiography. Cardiac index [median (range) 5.5 (3.2-8.1) vs 4.3 (3.2-7.5) l/min per m2, p < 0.01], intrathoracic blood volume [1125 (820-1394) vs 1037 (821-1267) ml/m2, p < 0.01], and right ventricular end-diastolic volume [130 (83-159) vs 114 (79-155) ml/m2, p < 0.05] increased significantly in the left dependent position compared to supine. Mean arterial pressure did not change. Atrial natriuretic peptide levels rose from 140 to 203 pg/ml. In the right dependent position, we found a marked decrease in the mean arterial pressure [85 mmHg (supine) to 72 mmHg (right dependent), p < 0.01]. Cardiac index and intrathoracic blood volume were unchanged, but right ventricular end-diastolic volume decreased from 114 to 102 ml/m2 (p < 0.05). Additionally, atrial natriuretic peptide levels decreased significantly (median delta value: 37 pg/ml). In echocardiographic controls we found an increase in right ventricular end-diastolic diameters in the left dependent position and shortened diameters in the right dependent position.

CONCLUSIONS

Extreme lateral posture affects the cardiovascular system in critically ill, mechanically ventilated patients: in the left dependent position a "hyperdynamic state" is reinforced, while the right decubitus position impairs right ventricular preload and predisposes to hypotension. Echocardiography and changes in plasma atrial natriuretic peptide values indicate that these findings are due to altered distensibility of the right ventricle caused by regional intrathoracic gravitational changes. We conclude that the duration and the angle of lateral posture should be restricted in hemodynamically unstable patients.

Cardiovascular and pulmonary effects of aerosolized prostacyclin administration in severe respiratory failure using a ventilator nebulization system

We investigated the effects of aerosolized prostacyclin (PGI2) administration on hemodynamics and pulmonary gas exchange in 8 patients with severe respiratory failure and acute pulmonary hypertension. Nebulization of epoprostenol (5 ng/kg body weight for 15 min) decreased mean pulmonary blood pressure from 41.2 +/- 6.7 mm Hg (mean +/- SD, before administration) to 36.1 +/- 6 mm Hg < or = 15 min (p < 0.05). The effect was reversed 10 min after discontinuation of PGI2 (40.9 +/- 6.3 mm Hg). Pulmonary vascular resistance index (339 +/- 138 dynes.s.cm-5.m2, before administration) was significantly (p < 0.05) reduced < or = 15 min (260 +/- 89 dynes.s.cm-5.m2) and increased again after discontinuation of PGI2 (341 +/- 142 dynes.s.cm-5.m2). The ratio of arterial oxygen to the fraction of inspired oxygen (PaO2/FiO2) increased from 119 +/- 34 mm Hg (before administration) to 163 +/- 76 mm Hg (15 min after initiation of administration p < 0.05) and was reduced after PGI2 discontinuation (116 +/- 35 mm Hg). Heart rate, mean blood pressure, central venous pressure, and pulmonary arterial wedge pressure remained unchanged, whereas cardiac index was slightly reduced. We assume that PGI2 aerosolization is a beneficial technique, applied with a ventilator nebulization system. The beneficial effect might be caused by selective pulmonary vasodilatation in well-ventilated areas of the lung.

Immunohistochemical localization of ciliary neurotrophic factor receptor alpha expression in the rat nervous system

Ciliary neurotrophic factor receptor alpha (CNTFR alpha) is essential for normal embryonic development and may be involved in postnatal and adult neuronal maintenance. In addition, a rapidly growing body of evidence suggests that CNTFR alpha serves as a site of action for future growth factor therapeutics capable of treating a wide variety of disorders resulting from neuronal loss. We raised two polyclonal, anti-CNTFR alpha antisera against synthetic peptides corresponding to independent regions of rat CNTFR alpha. Western blot and immunohistochemical analyses indicated that affinity-purified preparations of both antisera specifically recognize CNTFR alpha. In the adult brain, the highest levels of CNTFR alpha immunoreactivity were found in the perikarya, dendrites and, occasionally, the axons of several distinct classes of neurons including hippocampal formation neurons, some sensory neurons, and many neurons involved in motor control. CNTFR alpha immunoreactivity also was concentrated in the following: perikarya, dendrites, and axons of ventral horn motor neurons in adult spinal cord; perikarya and axons of adult dorsal root ganglion neurons; and axons in adult peripheral nerve. In embryonic tissue, the highest levels of CNTFR alpha immunoreactivity were observed in differentiating neurons and their processes. Therefore, the present data suggest that CNTFR alpha serves several diverse functions in adulthood and during development.

Right ventricular function and plasma atrial natriuretic peptide levels during fiberbronchoscopic alveolar lavage in critically ill, mechanically ventilated patients

STUDY OBJECTIVE

To assess the influence of fiberbronchoscopic alveolar lavage on hemodynamics, right ventricular function, and plasma atrial natriuretic peptide (ANP) concentrations in critically ill, mechanically ventilated patients.

DESIGN

Prospective investigation.

SETTING

Eight-bed ICU of a university hospital.

PATIENTS

Fourteen patients with cardiovascular instability due to a systemic inflammatory response syndrome who were mechanically ventilated.

INTERVENTIONS

Fiberbronchoscopic alveolar lavage after fluid replacement, deep sedation, and paralyzation. Intervention time: 10 min. After inspection of the endobronchial system, one lavage of 40 mL sterile saline solution was instilled in each lung and recovered.

MEASUREMENTS AND RESULTS

The fiberbronchoscopic procedure induced a prompt increase in mean pulmonary arterial pressure after 3 min (median[range]: 25 [13 to 39] to 30 [19 to 45] mm Hg, p < 0.05), which increased further after 6 min (34 [17 to 46] mm Hg, p < 0.01). Cardiac index increased simultaneously (4.25 [3.1 to 5.7] to 4.85 [4.3 to 6.9] L/min.m2 after 6 min, p < 0.01), whereas mean arterial pressure and heart rate remained unchanged. Central venous pressure rose from 12 (3 to 18) mm Hg before procedure to 14 (4 to 20) mm Hg after 6 min (p < 0.01). The right ventricular function was measured using a "fast response" ejection fraction thermodilution catheter: end-diastolic volume increased (238 [137 to 358] to 280 [150 to 4ll] mL after 9 min, p < 0.05), as well as stroke volume (88 [54 to 113] to 103 [67 to 153] mL after 9 min, p < 0.01). Right ventricular ejection fraction (37 [25 to 50] %) did not change significantly during the procedure, but the stroke work index was reinforced (8.2 [4.7 to 15.7] to 13.3 [2.4 to 41.3] gm.M/M2 after 6 min, p < 0.01). Plasma c-ANP concentration rose from 135 (24 to 350) to 196.5 (44 to 830 pg/ml after 20 min (p < 0.05). Systemic vascular resistance decreased from 533 (390 to 1,042) to 429 (281 to 684) dynes.s/cm5 after removal of the bronchoscope (p < 0.01).

CONCLUSIONS

Although acute pulmonary hypertension was observed during the fiberbronchoscopic procedure, the right ventricular performance did not deteriorate in hemodynamically unstable patients. To maintain a "hyperdynamic cardiovascular state," the right ventricular stroke work was reinforced, presumably by the "Frank-Starling mechanism." We assume that the acute distention of the right side of the heart resulted in elevated ANP concentrations. The marked decrease in systemic vascular resistance might be due to high ANP levels.

Cyclosporine A increases serum cortisol levels in rabbits

P-glycoprotein (P-gp), a membrane protein that was originally found to be involved in the efflux of cytotoxic drugs out of the tumor cells, is also present in a variety of normal human and animal tissues, such as the adrenal cortex. The function of P-gp in the adrenal cortex has not been defined yet. The aim of our study was to determine whether the blockade of P-gp by cyclosporine A (CsA) dissolved in Cremophor EL (Crem) inhibits cortisol secretion in rabbits. In 14 rabbits, the baseline and ACTH stimulated serum cortisol levels were measured before and after CsA treatment. Seven rabbits were treated with 2 x 30 mg/kg CsA and seven with 2 x 90 mg/kg CsA injected s.c. Serum cortisol levels were determined by radioimmunoassay adjusted for expected values. The whole blood CsA levels were determined by a commercially available fluorescence polarization immunoassay. Serum cortisol levels, both baseline and ACTH stimulated, significantly increased after both low and high dose CsA treatment. The increase was dose dependent. The mean baseline cortisol levels increased from 5.7 (SD = 6.3) to 15.0 nmol/l (SD = 7.2) in the low dose group and from 7.7 (SD = 4.9) to 44.9 nmol/l (SD = 13.8) in the high dose group. The mean cortisol levels 8 h after ACTH stimulation increased from 53.3 (SD = 34.5) to 106.0 nmol/l (SD = 33.0) in the low dose group and from 47.7 (SD = 12.2) to 153.0 nmol/l (SD = 55.1) in the high dose group.(ABSTRACT TRUNCATED AT 250 WORDS)

[Acute pulmonary and cardiovascular effects of continuous axial rotation (kinetic therapy) in respiratory failure]

AIM

Continuous lateral rotational therapy (kinetic therapy) is advocated to improve pulmonary gas exchange in patients with severe respiratory failure, by promoting mobilization of secretions and reducing mismatch of ventilation and perfusion. We analyzed the acute pulmonary and hemodynamic changes before and after beginning kinetic therapy in critically ill patients with inotropic support.

PATIENTS AND METHODS

Due to severe respiratory failure, 18 patients with "systemic inflammatory response syndrome" had been placed in a kinetic bed (Rotorest, KCI Mediscus). Retrospective analysis included several indices of arterial oxygenation, intrapulmonary "shunt fraction", cardiac index, arterial and pulmonary arterial pressure, systemic vascular resistance and systemic oxygen consumption.

RESULTS

After the start of kinetic therapy, we found a statistically significant improvement of pulmonary gas exchange and a reduction of shunt fraction 12 hours later. Cardiac index and arterial and pulmonary arterial pressure remained unchanged. Systemic oxygen consumption was increased.

CONCLUSION

The continuous axial rotation of patients with severe respiratory failure results in a prompt improvement of arterial oxygenation. Even in hemodynamically unstable patients we did not observe harmful effects.

Tissue-type plasminogen activator mutants imitating urokinase in the peptide link between kringle and protease domains and at selected sites within the protease domain

Tissue-type plasminogen activator (tPA) mutants which, at selected amino acid positions, mimic urokinase-type plasminogen activator (uPA) were expressed in Chinese hamster ovary cells and examined for their catalytic properties. In one series of mutants, the dipeptide Ser262 Thr263 between kringle 2 and the protease domain of tPA was (a) replaced by an Ala residue, (b) lengthened by additional Ser and Ala residues, (c) exchanged for the 16-amino-acid link between kringle and protease domains of uPA and an additional Ala residue. The activities of the latter two mutants toward plasminogen were, in the absence of fibrin, 3-5-fold higher and, in the presence of fibrin, comparable to or lower than the activity of tPA. The kinetic data suggest a short interdomain peptide in tPA as most favorable for high fibrin stimulation of tPA activity. In a second series of mutant, selected amino acid residues of the tPA protease domain were replaced by residues of the homologous uPA domain. Positions chosen for exchange are either close to the active site or are part of a tPA-specific insertion in the variable region preceding the active-site Ser residue. Compared to authentic tPA, protease-domain mutants exhibited 7.3-424-fold lower activities toward plasminogen, mainly due to lower kcat values. Km values differed only moderately. A mutant containing an additional hydroxyl group at the S1 site, tPA A473S, had lost the preference of tPA for Arg over Lys as the P1 residue in peptide substrates.

Risk of early-onset proliferative retinopathy in IDDM is closely related to cardiovascular autonomic neuropathy

Determinants of proliferative diabetic retinopathy (PDR) that occur during the 2nd decade of insulin-dependent diabetes mellitus (IDDM) (early-onset PDR) were investigated in a nested case-control study. From an inception cohort of patients with juvenile-onset IDDM that now has 15-21 yr diabetes duration, the patients with PDR (cases, n = 74) were selected for study along with a random sample of the patients in the cohort without PDR (control subjects, n = 88). The risk of PDR was associated with poor glycemic control during the first 12 yr of diabetes. Relative to patients in the first quartile of the index of hyperglycemia, those in higher quartiles and nonattenders had a four- to fivefold risk of developing PDR. A striking relationship with cardiovascular autonomic neuropathy (CAN) was found. Relative to patients without CAN, patients with significant and mild CAN had odds ratios of 77.5 and 34.6, respectively. Patients with albumin excretion rates greater than 30 micrograms/min had moderately increased risk of PDR (ranging from 4-fold for microalbuminuria to 7-fold for proteinuria). In contrast, patients with impaired renal function had an extremely high risk of PDR. All 20 of these patients were cases, therefore the odds ratio was infinite. All three factors (poor glycemic control, CAN, and various stages of nephropathy) were associated with PDR in multiple logistic regression analysis. However, in models including glycemic control, the association between microalbuminuria or proteinuria and PDR was weakened. In conclusion, our findings are consistent with a hypothesis that the level of glycemia is a primary determinant of early-onset PDR.(ABSTRACT TRUNCATED AT 250 WORDS)

[Proteolytic activities in bronchoalveolar lavage fluid in pneumonia and chronic bronchitis]

In 63 patients with chronic bronchitis, 61 patients with acute bacterial pneumonia, and in 11 control subjects, broncho-alveolar lavage fluid was investigated for its protease content. In smokers, we found the usual pronounced protease burden. As was expected, the two pathological groups also differed markedly on other points. In pneumonia, not only free elastase activity (from granulocytes (PMN] was markedly elevated, but also cathepsin-B-like activity (from alveolar macrophages (AM] was greatly increased, which would point up the important role of AM in this form of inflammatory. In this case of chronic bronchitis, function-analytically determinable obstruction parameters were associated with an increase in the elastase-like enzyme (from PMN), so that chronic obstructive bronchitis probably represents a special form of inflammation.