Impact of osteoporosis and osteoporosis medications on fracture healing: a narrative review

Antiresorptive medications do not negatively affect fracture healing in humans. Teriparatide may decrease time to fracture healing. Romosozumab has not shown a beneficial effect on human fracture healing.

BACKGROUND

Fracture healing is a complex process. Uncertainty exists over the influence of osteoporosis and the medications used to treat it on fracture healing.

METHODS

Narrative review authored by the members of the Fracture Working Group of the Committee of Scientific Advisors of the International Osteoporosis Foundation (IOF), on behalf of the IOF and the Société Internationale de Chirurgie Orthopédique et de Traumatologie (SICOT).

RESULTS

Fracture healing is a multistep process. Most fractures heal through a combination of intramembranous and endochondral ossification. Radiographic imaging is important for evaluating fracture healing and for detecting delayed or non-union. The presence of callus formation, bridging trabeculae, and a decrease in the size of the fracture line over time are indicative of healing. Imaging must be combined with clinical parameters and patient-reported outcomes. Animal data support a negative effect of osteoporosis on fracture healing; however, clinical data do not appear to corroborate with this. Evidence does not support a delay in the initiation of antiresorptive therapy following acute fragility fractures. There is no reason for suspension of osteoporosis medication at the time of fracture if the person is already on treatment. Teriparatide treatment may shorten fracture healing time at certain sites such as distal radius; however, it does not prevent non-union or influence union rate. The positive effect on fracture healing that romosozumab has demonstrated in animals has not been observed in humans.

CONCLUSION

Overall, there appears to be no deleterious effect of osteoporosis medications on fracture healing. The benefit of treating osteoporosis and the urgent necessity to mitigate imminent refracture risk after a fracture should be given prime consideration. It is imperative that new radiological and biological markers of fracture healing be identified. It is also important to synthesize clinical and basic science methodologies to assess fracture healing, so that a convergence of the two frameworks can be achieved.

Gene expression in human adipose-derived stem cells: comparison of 2D films, 3D electrospun meshes or co-cultured scaffolds with two-way paracrine effects

Finding the appropriate cues to trigger the desired differentiation is a challenge in tissue engineering when stem cells are involved. In this regard, three-dimensional environments are often compared to cells' two-dimensional culture behaviour (plastic culture dish). Here, we compared the gene expression pattern of human adipose-derived stem cells (ASC) seeded in a three-dimensional (3D) electrospun mesh and on a two-dimensional (2D) film - both of exactly the same material. Additionally, we conducted experiments with a scaffold floating above a film to investigate two-way paracrine effects (co-system). Electrospun meshes (3D scaffolds) and films (2D), consisting either of pristine poly-lactic-co-glycolic acid (PLGA) or of PLGA-containing dispersed amorphous calcium phosphate nanoparticles (PLGA/aCaP), were seeded with ASCs and cultured either in Dulbecco Minimum Essential Medium (DMEM) or in osteogenic medium. After two weeks, minimum stem cell criteria markers as well as typical markers for osteogenesis, endothelial cell differentiation, adipogenesis and chondrogenesis were analysed by quantitative real-time PCR. Interestingly, mostly osteogenic genes of cells seeded on 3D meshes were upregulated compared to those on 2D films, while stem cell markers seemed to be only slightly affected. Runx2 and osteocalcin showed an especially strong upregulation under all conditions, while most other factors analysed for 2D/3D changes were highly dependent on the material composition, the culture medium and on paracrine signalling effects. The beneficial 3D environment for stem cells found in many studies has therefore not to be attributed to the third dimension alone and should carefully be compared to 2D films fabricated of the same material. Furthermore, paracrine interactions triggering differentiation are not negligible.

Buprenorphine for pain relief in mice: repeated injections vs sustained-release depot formulation

Sustained-release formulations of analgesic drugs are promising alternatives to repeated drug injections. Here, we compared a sustained-release formulation of buprenorphine (SB, 2.2 mg/kg) with a standard protocol of three injections of buprenorphine (Temgesic, 0.1 mg/kg/8 h) in mice. Buprenorphine serum concentration and analgesic action (thermal sensitivity) were determined in healthy mice. Additionally, the pain relief properties of both protocols were assessed after laparotomy using physiological and ethological measures of pain and recovery. Serum concentrations and thermal sensitivity tests indicated duration of action of at least 4 h (but less than 8 h) with the Temgesic protocol, and 24–48 h with SB. Behavioural and clinical parameters indicated at least partial pain relief after surgery for both protocols. Observed side-effects of buprenorphine independent of the protocol were increased activity, disturbed circadian rhythm and several abnormal behaviours. A tendency for decreased food and water intake as well as body weight reduction was also seen. Body weight decreased significantly in animals that received three injections of Temgesic, regardless of whether surgery was performed or not ( P = 0.015; P = 0.023), hinting at a stress response towards this repeated intervention. In conclusion, an application interval of 8 h (Temgesic) appears too long and might lead to repeated periods with insufficient analgesia in animals undergoing lasting and/or substantial pain after surgery. In comparison to the standard protocol, SB provided a long-lasting, assured analgesia without possible stressful repeated injections in a standard surgical model, with only limited and acceptable behavioural side-effects.

Environmentally Compatible Foamed Articles Based on Potato Starch, Corn Fiber, and Poly(Vinyl Alcohol)

Potato starch foam trays based on blends of poly(vinyl alcohol) and corn fibers (CFs), co-product of the corn-wheat wet-milling process, are prepared by baking the blended mixtures in a preheated mold. Materials are evaluated for processing parameters, foam strength, flexibility, and water resistance as a function of fibers content. Addition of CF in formulations improved not only moisture resistance of foam, but has a potential to lower the overall cost of the foamed materials substantially. Interestingly, addition of up to 45% fiber in formulations was possible without compromising the foaming process. Degradability is evaluated both in compost than simulating a disposal in the environment (soil burying and soil surface). Trays are biodegraded within 30—60 days in compost and soil. Particularly, trays containing starch and fiber degraded at much faster rates than trays prepared using starch without natural fillers.

Gelatin-based blends and composites. Morphological and thermal mechanical characterization

Gelatin, a natural macromolecular proteic material from renewable resources, is widely used in many industrial applications. In this study gelatin scraps, deriving from pharmaceutical capsule productions, were turned into films by casting water solutions or suspensions producing flexible and consistent films. Gelatin was blended with poly(vinyl alcohol), a biodegradable synthetic polymer, in order to improve mechanical properties in the films. Gelatin was blended also with sugar cane bagasse, a lignin cellulosic waste from sugar cane processing. These blends showed good interface adhesion between gelatin and sugar cane fibers and mechanical properties of practical interest for up to 20% of sugar cane content by weight. Glutaraldehyde was used in different amounts as a cross-linking agent increasing elongation at break especially for amount above 1%. Morphology, thermal, thermomechanical, and mechanical properties of the samples were investigated by scanning electron microscopy (SEM), thermal gravimetric analysis (TGA), differential scanning calorimetry (DSC), dynamic mechanical thermal analysis (DMTA), and tensile tests, respectively. Cast films presented thermal and mechanical properties, which make them good candidates as biodegradable self-fertilizing mulching films.

Composite films based on biorelated agro-industrial waste and poly(vinyl alcohol). Preparation and mechanical properties characterization

As a part of an ongoing project on the production of composite materials based on poly(vinyl alcohol) (PVA) and polymeric materials from renewable resources, the present paper reports on the incorporation of agricultural waste materials as organic fillers in a film matrix based on PVA as continuous phase. In this study lignocellulosic fibers byproducts, derived from sugar cane (SC) and apple (AP) and orange (OR) fruit juice extraction, were cast from PVA aqueous solutions. The effect of fiber type and composition on the relative properties of cast films was evaluated and compared. OR resulted to be suitable for blending in higher amounts by weight than SC and AP. Glycerol and urea were added as plasticizing agents and were observed to be effective in giving flexible films. Additionally, cornstarch was added to further increase the composition of polymers from renewable resources in cost-effective and ecoefficient composite film formulations. The prepared films resulted sensitive to moisture and water. To reduce water sensitivity, hexamethoxymethylmelamine (HMMM) was tested as a cross-linking agent for the present composite formulations. Cross-linked films exhibited significant improvement in water-resistance that can be taken as a tuneable structural feature for customized applications. The mechanical properties of the prepared composite films (elongation at break, tensile strength, Young modulus) were found to be dependent upon the nature and content of the filler and on environmental conditions.

Neuroserpin, a neuroprotective factor in focal ischemic stroke

Because recent studies have indicated that tissue plasminogen activator (tPA) aggravates neurodegenerative processes in many neural pathologies, we studied whether the endogenous tPA antagonist neuroserpin has a neuroprotective effect in an animal model of focal ischemic stroke. After induction of a focal ischemic stroke in the mouse by occlusion of the middle cerebral artery, we found that microglial cells accumulated in the marginal zone of the infarct are the most important source for both plasminogen activators, tPA and uPA. To investigate the effect of neuroserpin on the size and the histology of the infarct we produced transgenic mice overexpressing neuroserpin approximately sixfold in the nervous system. In the brain of these mice the total tPA activity in the uninjured tissue was strongly reduced. After induction of a focal ischemic stroke in the transgenic mice by a permanent occlusion of the middle cerebral artery (MCA), the infarcts were 30% smaller than in the wild-type mice. Immunohistochemical analyses and in situ hybridization revealed an attenuation of the microglial activation in the reactive zone. Concomitantly, the microglial production of tPA and uPA, as well as the PA-activity in the infarct region was markedly reduced. Thus, our results indicate that neuroserpin reduces microglial activation and, therefore, the PA activity and has a neuroprotective role after focal ischemic stroke.

Multiple roles of neurotrypsin in tissue morphogenesis and nervous system development suggested by the mRNA expression pattern

We have mapped the spatio-temporal expression of the multidomain serine protease neurotrypsin in the developing mouse by in situ hybridization. On embryonic day (E) 8, mRNA is detected in giant trophoblast cells, later in embryonic mesenchymal tissues. On E11, expression begins in Schwann cell precursors, olfactory epithelium, trigeminal ganglion, and midbrain. The floor plate shows strong expression on E12. Further prenatal development is characterized by rising neurotrypsin mRNA in sensory ganglia and motor neurons. Staining in cerebral cortex emerges around birth and culminates toward the end of the first week with a complex laminar and areal pattern. Expression in peripheral nerves and nonneural tissues vanishes soon after birth and the adult neuronal distribution is gradually established until weaning age. This developmental expression pattern suggests roles of neurotrypsin in morphogenesis of nonneural tissues, as well as in neural development, in particular in axonal target invasion, synaptogenesis, and Schwann cell differentiation.

Neuronal depolarization enhances the transcription of the neuronal serine protease inhibitor neuroserpin

Neuroserpin is an axonally secreted neuronal serine protease inhibitor. Based on its inhibitory activity towards tissue plasminogen activator (tPA) and its predominant expression in the cerebral cortex, the hippocampus, and the amygdala, a role for neuroserpin in the regulation of neural plasticity has been suggested. We recently found that neuroserpin mRNA is increased in cultured hippocampal neurons upon depolarization with elevated extracellular KCl. Using luciferase reporter constructs containing segments of the promoter region of the neuroserpin gene, we identified a 200-bp segment near the transcription initiation site that is responsible for both the neuron-specific expression of the neuroserpin gene and the enhanced transcription resulting from depolarization. Nerve growth factor, which alone had no effect on the expression of neuroserpin mRNA in hippocampal neurons, had a marked potentiating effect when supplied in combination with elevated extracellular KCl. In contrast, the transcription factor zif/268 blocked neuroserpin transcription. These results implicate neuroserpin as an activity-regulated modulator of tPA activity at the synapse and provide further support for the occurrence of activity-regulated proteolytic processes at the synapse.

The axonally secreted serine proteinase inhibitor, neuroserpin, inhibits plasminogen activators and plasmin but not thrombin

Neuroserpin is an axonally secreted serine proteinase inhibitor that is expressed in neurons during embryogenesis and in the adult nervous system. To identify target proteinases, we used a eucaryotic expression system based on the mouse myeloma cell line J558L and vectors including a promoter from an Ig-kappa-variable region, an Ig-kappa enhancer, and the exon encoding the Ig-kappa constant region (C kappa) and produced recombinant neuroserpin as a wild-type protein or as a fusion protein with C kappa. We investigated the capability of recombinant neuroserpin to form SDS-stable complexes with, and to reduce the amidolytic activity of, a variety of serine proteinases in vitro. Consistent with its primary structure at the reactive site, neuroserpin exhibited inhibitory activity against trypsin-like proteinases. Although neuroserpin bound and inactivated plasminogen activators and plasmin, no interaction was observed with thrombin. A reactive site mutant of neuroserpin neither formed complexes with nor inhibited the amidolytic activity of any of the tested proteinases. Kinetic analysis of the inhibitory activity revealed neuroserpin to be a slow binding inhibitor of plasminogen activators and plasmin. Thus, we postulate that neuroserpin could represent a regulatory element of extracellular proteolytic events in the nervous system mediated by plasminogen activators or plasmin.

Expression of neuroserpin, an inhibitor of tissue plasminogen activator, in the developing and adult nervous system of the mouse

Neuroserpin is a serine protease inhibitor of the serpin family that has been identified as an axonally secreted glycoprotein in neuronal cultures of chicken dorsal root ganglia. To obtain an indication for possible functions of neuroserpin, we analyzed its expression in the developing and the adult CNS of the mouse. In the adult CNS, neuroserpin was most strongly expressed in the neocortex, the hippocampal formation, the olfactory bulb, and the amygdala. In contrast, most thalamic nuclei, the caudate putamen, and the cerebellar granule cells were devoid of neuroserpin mRNA. During embryonic development, neuroserpin mRNA was not detectable in neuroepithelia, but it was expressed in the differentiating fields of most CNS regions concurrent with their appearance. In the cerebellum, the granule cells and a subgroup of Purkinje cells were neuroserpin-positive during postnatal development. As a further step toward the elucidation of neuroserpin function, we performed a study to identify potential target proteases. In vitro, neuroserpin formed SDS-stable complexes and inhibited the amidolytic activity of tissue plasminogen activator, urokinase, and plasmin. In contrast, no complex formation with or inhibition of thrombin was found. Expression pattern and inhibitory specificity implicate neuroserpin as a candidate regulator of plasminogen activators, which have been suggested to participate in the modulation or reorganization of synaptic connections in the adult. During development, neuroserpin may attenuate extracellular proteolysis related to processes such as neuronal migration, axogenesis, or the formation of mature synaptic connections.

Implementation of total quality management after reconfiguration of services on a general hospital unit

In 1992 the New York State Office of Mental Health issued a statewide plan for mental health services to reduce the number of inpatient beds in state-run facilities from approximately 11,000 to between 6,000 and 8,000 by the year 2000. This reduction resulted in at least a 25 percent increase in psychiatric beds at local general hospitals. In 1992 Albany Medical Center Hospital's department of inpatient psychiatry established an interdisciplinary committee to address changes resulting from the reconfiguration of services to chronic mentally ill persons. The committee established procedures to use the principles of total quality management to respond to problems and to continuously improve the therapeutic milieu. The authors describe how these principles were used to create a patient satisfaction survey, to examine and improve part of the hospital admissions procedure, and to review and revise treatment planning documentation. A concurrent review committee reviews patients' records to ensure accuracy of documentation and quality of care.

Low incidence of cardiac hypertrophy in essential hypertensives with no retinal changes

120 subjects, 90 hypertensives and 30 age-matched controls, were evaluated by fundoscopy and echocardiography to assess the degree of target organ involvement. The hypertensive patients were divided into 3 groups (mild, moderate, severe hypertension) according to their diastolic blood pressure levels. No significant difference was demonstrated in left ventricular mass among the 3 groups. Moreover, no relationship was demonstrated between the degree of hypertension and the severity of fundoscopic changes. Our findings indicate that patients with no retinal changes show a low probability of left ventricular hypertrophy and that patients with left ventricular hypertrophy show a high probability of retinal involvement. Our data indicate that fundoscopy is more sensitive than echocardiography in the recognition of the hypertensive disease.

Ventricular late potentials in the assessment of mitoxantrone cardiotoxicity

Sixteen female patients underwent signal-averaged electrocardiography and radionuclide angiography for the assessment of the resting left ventricular ejection fraction in the course of chemotherapy with mitoxantrone (MTX) for advanced breast cancer. Nine patients had received prior cardiotoxic treatments. Our findings indicate that patients treated with MTX may develop late potentials.

A chronobiological study on the relation between heart rate and QT interval duration in newborn infants

The relation between heart rate and QT interval is the result of the autonomic nervous system control on cardiac function in healthy adults; accordingly, chronobiological studies have shown that adult subjects have circadian rhythms of heart rate (expressed as R-R interval) and QT interval in phase. We have employed chronobiological methods to study heart rate and QT interval relation in 10 newborn infants, who are known to have an immature cardiac control. Findings from this study indicate that not all the newborns show circadian rhythms of heart rate and QT interval and that when both rhythms are present they do not correlate like in the adults. Likely, this lack of relationship between heart rate and QT interval in newborns is due to different maturational stages of the newborns studied. As a practical implication, in newborn infants, mathematical correction of QT interval by heart rate is not a reliable method.

Does ergometric stress test induce a procoagulative condition in patients with previous myocardial infarction?

A regularly scheduled physical training program seems to have antithrombotic effects. Moreover, the hemostatic changes occurring in patients with coronary artery disease during acute exercise have not been clearly elucidated. Since stress testing is routinely performed in clinical cardiology, it would be helpful to assess whether patients with coronary artery disease are exposed to acute coronary thrombosis during or soon after sustained physical exercise. This study was designed to evaluate the effect of acute physical exercise (stress test by bicycle ergometer) on blood coagulation in a group of patients with previous myocardial infarction, and to determine whether the antithrombotic therapy commonly administered favorably influences hemostatic equilibrium. Our results suggest that exercise testing is not harmful to patients with previous myocardial infarction in regard to hemostasis and fibrinolysis and that antithrombotic therapy reduces postexercise increase in platelets.

Echocardiographic evaluation of children with and without family history of essential hypertension

A family history of hypertension is considered a risk factor for developing hypertension. We studied two groups of normotensive children (aged 14 years): one comprising 14 subjects with family history of hypertension, the other comprising 15 subjects without family history of hypertension. Children were comparable with respect to age, weight, height, body surface area, heart rate, and arterial blood pressure. M-mode echocardiography demonstrated higher interventricular septum/posterior wall ratio in progeny of hypertensive subjects. Interestingly, all the parameters evaluated were within the normal limits. Our data suggest that a certain degree of cardiac changes is present in children with positive family history of hypertension, though further studies are needed before considering these findings predictive of future essential hypertension.

Response of some haemocoagulatory and haemorheological variables to maximal exercise in sedentary and active subjects

The purpose of this study was to evaluate how physical conditioning is associated with haemostatic and rheological responses to strenuous exercise. A total of 25 males, divided into two groups differing in exercise fitness (14 sedentary and 11 active), underwent exercise testing on a bicycle ergometer with an initial 25 W workload increasing by the same amount every 3 min. The following variables were evaluated before and after the test: platelet count and aggregability, plasma fibrinogen, fibrinolytic degradation products, viscometry and micro-haematocrit. Significant differences in baseline values between the two groups were found only for blood viscosity. Irrespective of the group, significantly increased values were demonstrated for all the variables, except platelet aggregability and fibrinogen levels, in response to strenuous exercise. It is concluded that the possible protective effect of exercise against cardiovascular disease does not seem to be related to changes in the haemorheological and haemostatic measures evaluated.

Circadian variations of heart rate and premature beats in healthy subjects and in patients with previous myocardial infarction

Chronobiological analysis of the circadian variations of heart rate, ventricular and atrial ectopies, was carried out on 11 patients with previous myocardial infarction matched with 11 controls. Individual circadian rhythms in heart rate were seen in all the control subjects but only in 6 patients with previous myocardial infarction. The behaviour of the individual circadian rhythms of premature beats was not significantly different between the two groups. A significant group rhythm in ectopies was not demonstrated, nevertheless a trend to higher frequency of arrhythmias during the activity span was detected. These results do not allow to postulate a circadian pattern of arrhythmias common to all the subjects examined. Therefore, the individual circadian behaviour of premature atrial and ventricular beats should be recognized for monitoring antiarrhythmic therapy. A significant group rhythm in heart rate was demonstrated for the two populations studied and linear discriminant analysis showed that the amplitude of this rhythm was significantly lower in patients than in controls. Possibly, myocardial infarction may affect the sinus node function producing a "flattened" range of heart rates during the 24 hours.

[Circadian and ultradian rhythms of the heart rate in the neonate]

Few papers deal with the chronobiologic characteristics of heart rate in neonates. A better knowledge of this topic could be useful under both clinical and therapeutical point of view. We studied the circadian and ultradian rhythms of heart rate in 10 healthy neonates (5 males and 5 females). Six of them (60%) show a well defined circadian rhythm of heart rate such as adult subjects even if with an obviously higher mesor and with acrophases dispersed throughout the 24 hours. We also demonstrated one or more ultradian rhythms of heart rate for each neonate. The most frequent have a period between 4 hours and 6 minutes and 4 hours and 36 minutes. These rhythms are out of phase with the world outside which is the best evidence that they are not imposed by some undetected external factors.

Relationship between systolic time intervals and arterial blood pressure

It has been suggested that systolic time intervals (STI) can be used to monitor the cardiac effects of antihypertensive treatments and also to evaluate hypertensive patients. STI changes observed in hypertensives have been ascribed to myocardial disease, although they could be due to the existence of a relationship between STI and blood pressure. A group of 37 subjects (18 normotensives and 19 hypertensives) with no signs of heart failure and left ventricular dysfunction were studied to examine the relationship of STI to blood pressure. Pacing with an external battery pulse generator was performed at the rate of 95 beats/min in order to eliminate differences in heart rate. STI were measured from good quality high speed (100 mm/s) recordings and the average value of 10 consecutive cardiac cycles was used for statistical analysis. Normal subjects showed significantly lower values of pre-ejection period (PEP), electromechanical systole (QS2), and pre-ejection period/left ventricular ejection time ratio (PEP/LVET). Moreover, a significant inverse relationship between diastolic pressure and LVET and significant direct relationships between diastolic pressure and PEP, systolic pressure and PEP, diastolic pressure and PEP/LVET, and between systolic pressure and PEP/LVET were demonstrated. We suggest to consider the relation of STI to blood pressure to provide regression equations to best appreciate and use STI.

Muscular blood flow in patients with heart failure

We studied reactive hyperemia in a group of patients with heart failure before and after therapy, since changes in the characteristics of muscular blood flow may influence the functional class of these patients. At the same time we evaluated some echocardiographic parameters too. When the patients improved clinically, they showed an increase in muscular blood flow at rest and in percent of fractional shortening and a decrease in peripheral vascular resistance. The reactive hyperemia did not change significantly. This fact probably depends on a maximal response to the postischemic hyperemia and represents the integrity of autoregulatory mechanisms.

Evidence of no interobserver variability in M-mode echocardiography

Left ventricular internal dimensions, septal and posterior wall thickness, aortic root diameter, and left atrial dimensions, were independently measured by two experienced interpreters on 50 consecutive routinely performed M-mode echocardiograms. The purpose of this work was to evaluate the reproducibility of these measurements and to assess if a different "diagnostic effect" could be provided by the two readers. The extent of interobserver variability was calculated and expressed as a percent of the mean. No significant interobserver variability was found for all the measured echocardiographic parameters and the two interpreters gave rise to the same "diagnostic effects." Therefore, the authors suggest following well stated guidelines to provide uniformity in the process of determining the boundaries of the structures to be measured and adjusting the actual measurements by multiplying by a conversion factor (representing the ratio between the number of 1 cm markers and the distance in centimeters between the first and the last marker), as opposed to interpolating between the marks on the recording paper.

Circadian rhythms of arterial blood pressure

We measured variations of blood pressure during the day in 46 untreated outpatients (25 hypertensives and 21 normotensives) to assess their circadian patterns. The self-measured blood pressures (autorhythmometry), determined at 08:00, 12:00, 16:00, 20:00 and 23:00 for 40 consecutive days were evaluated chronobiologically from single and population mean cosinors. On the basis of the results, we conclude that it is impossible to propose a common schedule of temporal therapy that will be effective for all hypertensive patients because of the unpredictable circadian behavior of blood pressure in this kind of subjects. Therefore, we suggest that individual circadian patterns of arterial pressure be studied when therapy is being established, so that the best therapeutic results can be achieved.

A chronobiologic study on some cardiovascular parameters

We studied the chronobiologic pattern of heart rate, R and T wave voltage, QT interval, and ST segment displacement. Premature atrial and ventricular beats obtained by dynamic electrocardiography, as well as arterial blood pressure measurements obtained by autometry, have also been studied in 131 untreated subjects (25 with hypertension, 28 with major risk factors for coronary artery disease, 9 with coronary artery disease, 37 presumably healthy and 11 shift workers). Our results show the existence of circadian rhythms in heart rate, in the duration of the QT interval and also in the voltage of R and T waves. Our data for R and T wave voltages do not completely agree with those from other authors. We demonstrated also that smoking may influence the circadian acrophase of the rhythm in R wave voltage while sleeping does not show any relationship with R and T wave voltages although it seems related to the displacement of the ST segment. We could point out only small differences in the chronobiologic behavior of patients with coronary disease and that of normal subjects, unlike the results previously reported by other authors. Our study demonstrated the existence of circadian and ultradian rhythms in premature atrial and ventricular beats as well as circadian and circaseptan rhythms in arterial blood pressure. Further studies are needed to improve our chronobiologic knowledge in order to optimize dosage and time of administration of the drugs used in the long term management of arrhythmias and hypertension.

Effects of isoproterenol and methoxamine on the electrocardiogram

The effects of isoproterenal (ISP) and methoxamine (MTX) infusion in 20 asymptomatic subjects with labile T wave were studied. In those treated with ISP the T wave showed an early negative trend and later became clearly positive in 5 subjects. In the majority of the subjects treated with MTX the T wave became positive. T wave changes match variations of both the ventricular gradient and, to a lesser degree, the QRS area. These changes were not related to heart rate or, in the subjects treated with MTX, to the baroreceptorial sensitivity deduced from the slope of the regression equation between R-R internal and systolic arterial pressure. The results of this study confirm the existence of a neurogenic mechanism affecting the electrocardiographic changes in T wave.

Clinical electrophysiological effects of chronic administration of verapamil: the phenomenon of overdrive excitation of junctional pacemaker

The electrophysiological effects of chronic administration of verapamil were studied in 10 patients with normal sinus node function, who received 160 mg of the drug every eight hours for at least two weeks. Uncorrected and corrected sinus node recovery time, sino-atrial conduction time, effective and functional refractory periods were normal in each case. In three patients, at the cessation of atrial pacing, an overdrive excitation of junctional pacemaker with short lasting A-V dissociation was observed.

Heart rate and premature beats: a chronobiologic study

Sixteen subjects, mean age 59 +/- 18, 11 normal and 5 with coronary artery disease, all having premature ventricular and/or atrial beats in the standard resting electrocardiogram (ECG), were studied to analyse the chronobiologic parameters of these arrhythmias. Single cosinor analysis of the data obtained by 96-hour ECG performed according to the Holter system, demonstrated: A) significant circadian rhythm in heart rate for all the subjects, with acrophases occurring between 12.56 and 17.36; B) significant circadian rhythms of premature ventricular beats for the majority of the subjects, with acrophases distributed along the 24 hours; C) significant circadian rhythms in premature atrial beats for 8 subjects, with acrophases occurring between 04.24 and 18.12; D) a spectrum of significant ultradian rhythms in heart rate with various periodicities, both in normal and in coronary patients; E) significant ultradian rhythms in premature ventricular beats for 8 subjects with periods ranging from 5h 15' to 17h. Population mean cosinor analysis demonstrated: A) significant circadian group rhythm in heart rate for all the 16 subjects and for the group of 11 normal subjects; B) no significant circadian group rhythm for premature ventricular and atrial beats. These findings suggest that the study of the individual chronobiologic pattern of premature beats may help to optimize antiarrhythmic therapy.

Computerized M-mode echocardiography in the assessment of cardiovascular effects during intravenous administration of amiodarone

Antianginal and antiarrhythmic long term therapy with amiodarone may be associated with side effects, therefore it should be used mainly in short term treatment of severe arrhythmias and acute coronary insufficiency. It is important to assess if any inotropic effect may be produced after intravenous administration of this drug in commonly accepted therapeutic doses (5 mg/kg body weight). To investigate this possibility we studied the effects of amiodarone on blood pressure (BP), on heart rate (HR) and on the maximal velocity of circumferential fiber shortening (Vcf Max). Simultaneous echocardiogram (UCG), electrocardiogram (lead DII) (ECG) and BP cuff measurement were performed on 12 subjects without cardiomegaly and clinical evidence of heart failure, immediately before a 30 second intravenous injection of amiodarone and every 30 seconds over a period of 6 minutes after drug administration. Amiodarone administration markedly raised HR within the first 30 seconds from the beginning of the injection and concomitantly decreased diastolic BP. No significant lowering of systolic BP was observed. Vcf Max (circ/sec) raised during the test concomitantly with HR increase, showing a significant relationship between left ventricular performance and HR. The same was also true during atrial pacing performed on one subject. No significant changes in any of the parameters studied were demonstrated after placebo (saline solution) administration to two presumable healthy subjects. Amiodarone does not seem to have any positive or negative intrinsic inotropic effect when administered intravenously at a dose of 5 mg/kg body weight.

Circadian rhythms in dynamic electrocardiography

A group of ten healthy subjects aged 32-58 years was studied by dynamic electrocardiography. An electrocardiogram (ECG) was recorded on CM 5 lead for 14 seconds every 15 minutes during the 24 hours. All the subjects were under a similar nyctohemeral schedule, sleeping between 23.30 and 06.45, and all followed their spontaneous diet without any restriction. "Mean Cosinor" analysis of the data revealed statistically significant circadian rhythms of heart rate (HR), R and T-wave voltages, duration of the QT interval and ST segment displacement, but not of the duration of the corrected QT (QTc).

An attempt to establish early signals of peripheral arterial disease (PAD): the use of rhythm's parameters of peripheral blood flow (RF)

Rhythm parameters of peripheral arterial rest blood flow (RF) as a potential predictor of peripheral arterial disease (PAD) have been investigated. Three groups of subjects have been studied: a. six apparently healthy subjects; b. seven high risk (hypertension, diabetes, hypercholesterolaemia, hypertriglyceridaemia, erythrocytosis) subjects; c. four occlusive PAD selected patients with one 'pre-symptomatic' leg. RF has been measured by 'strain-gauge plethysmography' every min for 25 min, 4 times/day. Right fore-arm, right leg and left leg have been assessed. Data have been analyzed by 'single and population mean cosinor'. Significant circadian rhythms have been detected in apparently healthy subjects. Mesor and amplitude can differ according to single individual's area. Mesor is higher in upper limb. RF circadian rhythm parameters differ in subjects with various vascular risk load. Sometimes, PAD-symptomatic limb shows higher mesor than pre-symptomatic one, suggesting conditions of reactive post-ischemic hyperemia or a role of RF in PAD. Circadian dyschronia can be detected in PAD limbs but also in high risk subjects, perhaps an example of chronoprotopathology. These results suggest the possibility of a clinical use of RF rhythm parameters as predictors of vascular protopathology.

Toward a medical prolepsis by chronobiology

Medicine today strongly aims at prevention and optimization of diagnosis and therapy Studies tried staging and standardization of clinical trials in diseases and made search of markers for early diagnosis, prognosis and therapy. Moreover, risk factors and other variables such as predictors are now investigated more often in groups or populations of apparently healthy subjects, especially for such diseases as atherosclerosis and neoplasia. This new aspect of increasing interest may be defined as medical prolepsis (from the Greek pi rho ómicron lambda eta psi iota zeta = anticipated idea). It includes early signals of disease (protopathology) as well as other signals the host shows as defence or alarm reaction. Hence, we suggest a chronobiological approach in this field, which allows to quantify health and reveals more subtle differences in many physiological variables. According to these views, we reported studies concerning humoral markers and other parameters considered as risk factors both in atherosclerosis and in some endocrine tumors.

Bioavailability of digoxin and beta-methyl-digoxin

In a randomized crossover study the bioavailability of a single dose of digoxin and of beta-methyl-digoxin tablets was tested in four normal volunteers. No difference was found between the two products in the rate and extent of drug absorption using 6 day cumulative urinary excretion and serial serum concentration measurements.

[Normal echogram of the mitral valve. Study of 50 normal, military-age subjects]

The mitral echograms of 50 normal subjects of military age were studied and basic parameters compared with anthropometric data and heart frequency; unlike what has been found by other workers, no significant statistical correlation was observed. Mean values of the parameters used are not substantially different to those reported in the literature consulted although deeper statistical studies are required if more valid standards are to be found.