Indications for Treatment of Complete Atrioventricular Dissociation

For purposes of correct treatment it is important to recognize that patients with complete atrioventricular dissociation fall into three groups: Group I—established third-degree heart block with and without Stokes-Adams attacks; Group II—periodic third-degree heart block with and without Stokes-Adams attacks; Group III—established third-degree heart block with cardiac failure. Most patients in Group I present no technical problems when a pacemaker is implanted. In Group II it is advisable to insert a temporary intracardiac catheter electrode and maintain a rate of 60 to 64 during the periods of third-degree heart block. Sudden reversion, in this group, from sinus rhythm can be fatal. Group III patients will often require a pacemaker set in excess of 74 beats until they are free of cardiac failure. Fifteen of 20 patients with complete atrioventricular dissociation showed marked functional improvement after insertion of a pacemaker. The development, in our laboratory, of a 4″ portable pacemaker impulse detector has been invaluable in locating the cause of failure in an implanted pacemaker.     

Management of Ingested Foreign Bodies in Childhood

A total of 660 patients with ingested foreign bodies admitted to the general surgical services in two children''s hospitals in Liverpool are reviewed. Endoscopic removal (205 cases) is recommended for all foreign objects impacted in the oesophagus, with the exception of rounded or blunt objects in the lower third, which should be observed for a maximum of 12 hours. The indications for laparotomy for removal of a foreign body (43 cases, 6·5%) are the danger of perforation and failure of progression. The ingestion of a long slender object—for example a hair-grip—in a child under 2 years of age, is an absolute indication for prophylactic operative removal owing to the high incidence of impaction and perforation of the duodenum.     

A Novel Effect in Phycomyces Phototropism : Positive Bending and Compensation Spectrum in Far UV

A novel effect—positive phototropic bending under far UV irradiation (between 260 and 305 nanometers) at low intensities—is reported. Natural compensation points (intensities which cause no bending under unilateral irradiation) have been determined for different wavelengths. The curve connecting these points, the compensation spectrum, divides the intensity-wavelength plane into areas of negative and positive tropism. It is further shown that a highly asymmetrical pattern of light stimulus within the sporangiophore underlies the symmetrical growth response at each compensation point. This suggests that some unknown additional factor is involved in perceiving a UV stimulus at the level of the photoreceptor. It is also demonstrated here that positive tropism in the UV range is due to a lens effect. We conclude that the hypothesis of optical attenuation of the stimulus (considered until now as the most plausible explanation of negative tropism in the UV spectral range) must be dismissed. The results presented here represent the first application of our quantitative theoretical consideration of spatial factors in phototropism heretofore neglected by others.     

Surgical Procedures in Nonagenarians

During the hospital course of 225 nonagenarian patients who underwent 285 major operations—80% on the general, vascular, orthopedic and urologic services—overall morbidity was 37% and mortality 7.5%. The 100 emergency operations were associated with a higher morbidity and mortality rate. Nonsurvivors were more likely to have associated cardiac or cerebral medical conditions, higher utilization of intraoperative invasive hemodynamic monitoring and greater use of surgical intensive care units. Compared with all surgical patients, the nonagenarians were admitted twice as often to the surgical intensive care unit, required twice the number of hospital days, underwent intraoperative hemodynamic monitoring twice as frequently and incurred 200% greater hospital charges. We conclude that with careful evaluation and management, a nonagenarian patient presenting with a surgical condition can safely undergo necessary operative procedures.     

Modeling herbivore functional responses causing boom‐bust dynamics following predator removal

Native biodiversity is threatened by invasive species in many terrestrial and marine systems, and conservation managers have demonstrated successes by responding with eradication or control programs. Although invasive species are often the direct cause of threat to native species, ecosystems can react in unexpected ways to their removal or reduction. Here, we use theoretical models to predict boom‐bust dynamics, where the removal of predatory or competitive pressure from a native herbivore results in oscillatory population dynamics (boom‐bust), which can endanger the native species’ population in the short term. We simulate control activities, applied to multiple theoretical three‐species Lotka‐Volterra ecosystem models consisting of vegetation, a native herbivore, and an invasive predator. Based on these communities, we then develop a predictive tool that—based on relative parameter values—predicts whether control efforts directed at the invasive predator will lead to herbivore release followed by a crash. Further, by investigating the different functional responses, we show that model structure, as well as model parameters, are important determinants of conservation outcomes. Finally, control strategies that can mitigate these negative consequences are identified. Managers working in similar data‐poor ecosystems can use the predictive tool to assess the probability that their system will exhibit boom‐bust dynamics, without knowing exact community parameter values.     

New Trends in the Treatment of Angina Pectoris

Traditionally when considering the pharmacologic basis of therapy in angina pectoris, attention is focussed on alterations of coronary blood flow. Yet the diseased coronary arteries in these patients often do not appear to be capable of responding to vasodilatory drugs. Since the pain of myocardial ischemia is relieved by a number of interventions without an increase in coronary blood flow, the concept herein considered is that angina pector is best viewed as an unfavorable relation between myocardial oxygen requirements and availability. Thus, the clinical value of the major antianginal agents is thought to be based importantly upon their actions to reduce myocardial oxygen consumption rather than to increase coronary blood flow.Sublingual nitroglycerin possesses a powerful dilator effect on veins which reduces venous return and thereby the size of the heart and intra-myocardial tension; thus myocardial oxygen requirements are diminished.The beta-adrenergic receptor blocking drug, propranolol (Inderal®), inhibits sympathetic stimulation of the heart at rest and during exercise. Thus, myocardial oxygen requirements are diminished by the reduction in heart rate and diminished contractility. As a result of this latter action, cardiac output is reduced and thereby arterial pressure and intramyocardial tension is lowered. In patients with advanced heart disease and borderline cardiac compensation, propranolol is hazardous because it removes the availability of one of the important reserve mechanisms for maintaining cardiac compensation—the sympathetic support of the failing heart.The introduction of electrical stimulation of the carotid sinus nerves as a means of therapy in patients with angina pectoris has provided a powerful tool for the treatment of patients with refractory ischemic pain.     

ATTITUDES TOWARD THE DUBIOUS COMPENSATION CLAIM

Laws providing for compensation of workmen for occupational injury are a powerful socio-economic force.In settlement of compensation claims the goal, difficult to achieve, is fairness to employee, employer and insurance carrier. Often, medical, legal, economic and social considerations conflict with one another. A “fact” in one field may not be considered so in another.Since medical data and testimony often guide the ultimate decision of a compensation claim, the physician''s attitude is a large factor not only immediately and directly in determination of the case at hand but, perhaps more important, in the ultimate direction of the socio-economic forces which spring from the sum of all such determinations.To perpetuate the good in workmen''s compensation laws, the next generation of physicians—and of lawyers and business administrators as well, for they, too, are involved—ought to have basic training in the social sciences in order that they may have a broad rather than a segmental view of the problems with which they deal.     

The Nature of Quantitative Genetic Variation in Drosophila. III. Mechanism of Dosage Compensation for Sex-Linked Abdominal Bristle Polygenes

Seventeen lines, each homozygous for a different X chromosome but all with a common autosomal genetic background, were constructed and assayed for abdominal bristle number to determine whether dosage compensation operates for sex-linked genes affecting this character.—The regression coefficient of male mean on female mean using a logarithmic scale was 0.90 ± 0.13 and the genetic regression coefficient 0.92, neither differing significantly from unity. The genetic components of variance in males and females were also very similar (0.000234 or 0.000228, respectively). These results indicate that dosage compensation is complete (or nearly so) for sex-linked genes affecting this character. The bristle scores of females did not differ in reciprocal crosses between these lines, thus dosage compensation does not operate by paternal X inactivation.—The question of an adequate scale for abdominal bristle number had to be examined during the study. A logarithmic scale appeared to be adequate for both genotypic and environmental differences.     

Sudden Death in Hospital after Discharge from Coronary Care Unit

In a group of 339 patients with acute myocardial infarction treated in a coronary care unit, 273 left the unit while improving and were expected to leave hospital alive; 23 had a cardiac arrest or died suddenly while still in hospital—17 died immediately or after temporary resuscitation and six were resuscitated to leave hospital alive. Ventricular fibrillation was found in 13 of the 20 patients attended by the cardiac arrest team. The incidents were scattered from the 4th to the 24th day after the onset of infarction. Risk factors in these “late sudden death” patients were compared with the 250 patients who left the unit while improving and did not die or suffer cardiac arrest. The patients susceptible to late sudden death were characterized early in their hospital course by the findings of severe, predominantly anterior infarction, left ventricular failure, persistent sinus tachycardia, and frequent ventricular arrhythmias. It is suggested that such patients be chosen for prolonged observation in a second-stage coronary care unit.     

Sounding out the hidden data: A concise review of deep learning in photoacoustic imaging

The rapidly evolving field of photoacoustic tomography utilizes endogenous chromophores to extract both functional and structural information from deep within tissues. It is this power to perform precise quantitative measurements in vivo—with endogenous or exogenous contrast—that makes photoacoustic tomography highly promising for clinical translation in functional brain imaging, early cancer detection, real-time surgical guidance, and the visualization of dynamic drug responses. Considering photoacoustic tomography has benefited from numerous engineering innovations, it is of no surprise that many of photoacoustic tomography’s current cutting-edge developments incorporate advances from the equally novel field of artificial intelligence. More specifically, alongside the growth and prevalence of graphical processing unit capabilities within recent years has emerged an offshoot of artificial intelligence known as deep learning. Rooted in the solid foundation of signal processing, deep learning typically utilizes a method of optimization known as gradient descent to minimize a loss function and update model parameters. There are already a number of innovative efforts in photoacoustic tomography utilizing deep learning techniques for a variety of purposes, including resolution enhancement, reconstruction artifact removal, undersampling correction, and improved quantification. Most of these efforts have proven to be highly promising in addressing long-standing technical obstacles where traditional solutions either completely fail or make only incremental progress. This concise review focuses on the history of applied artificial intelligence in photoacoustic tomography, presents recent advances at this multifaceted intersection of fields, and outlines the most exciting advances that will likely propagate into promising future innovations.     

Left Ventricular Dilation and Pulmonary Vasodilatation after Surgical Shunt for Treatment of Pre-Sinusoidal Portal Hypertension

ObjectiveThe aim of this study was to prospectively investigate the long-term cardiovascular and pulmonary hemodynamic effects of surgical shunt for treatment of portal hypertension (PH) due to Schistosomiasis mansoni.LocationThe University of São Paulo Medical School, Brazil; Public Practice.MethodsHemodynamic evaluation was performed with transesophageal Doppler and contrast-enhanced echocardiography (ECHO) on twenty-eight participants with schistosomal portal hypertension. Participants were divided into two groups according to the surgical procedure used to treat their schistosomal portal hypertension within the last two years: group 1—distal splenorenal shunt (DSRS, n = 13) and group 2—esophagogastric devascularization and splenectomy (EGDS, n = 15).ResultsThe cardiac output (5.08 ± 0.91 L/min) and systolic volume (60.1 ± 5.6 ml) were increased (p = 0.001) in the DSRS group. DSRS participants had a significant increase (p < 0.0001) in their left ventricular end-systolic and end-diastolic diameters as well as in their left ventricular end-diastolic and end-systolic volumes (p < 0.001) compared with the preoperative period. No statistically significant difference was found in the patients who underwent EGDS. ECHO revealed intrapulmonary vasodilatation (IPV) in 18 participants (64%), 9 DSRS and 9 EGDS (p > 0.05).ConclusionsThe late increase in the cardiac output, stroke volume and left ventricular diameters demonstrated left ventricular dilatation after a distal splenorenal shunt. ECHO revealed a greater prevalence for IPV in patients with schistosomiasis than has previously been described in patients with PH from liver cirrhosis.     

Patterns of Cervical Spine Injury and Their Associated Lesions

Motorcycle riding and diving into shallow water continue to present a high risk of cervical spine injury, often complicated by spinal cord damage. In patients with high cervical cord trauma, differentiation of arterial hypotension due to losing vasomotor control from the effects of internal hemorrhage can cause difficulty. In a series of 123 consecutive cases of cervical spine injury, no evidence was found that either early surgical treatment or steroid administration exert a favorable influence on recovery from traumatic myelopathy. When compared with other series, differences were found in the nature, frequency and severity of both spinal and associated injuries, resulting from the relative frequency among the population studied of trauma due to a particular mechanism—traffic accident, diving, industrial injury—and the special functions and location of the hospital from which information is gathered.     

A bottom-up characterization of transfer functions for synthetic biology designs: lessons from enzymology

Within the field of synthetic biology, a rational design of genetic parts should include a causal understanding of their input-output responses—the so-called transfer function—and how to tune them. However, a commonly adopted strategy is to fit data to Hill-shaped curves without considering the underlying molecular mechanisms. Here we provide a novel mathematical formalization that allows prediction of the global behavior of a synthetic device by considering the actual information from the involved biological parts. This is achieved by adopting an enzymology-like framework, where transfer functions are described in terms of their input affinity constant and maximal response. As a proof of concept, we characterize a set of Lux homoserine-lactone-inducible genetic devices with different levels of Lux receptor and signal molecule. Our model fits the experimental results and predicts the impact of the receptor''s ribosome-binding site strength, as a tunable parameter that affects gene expression. The evolutionary implications are outlined.     

Discordance, in a Malignant Hyperthermia Pedigree, between in Vitro Contracture-Test Phenotypes and Haplotypes for the MHS1 Region on Chromosome 19q12–13.2, Comprising the C1840T Transition in the RYR1 Gene

A point mutation in the gene encoding the skeletal muscle calcium release channel (RYR1) has been proposed as the probable cause of malignant hyperthermia (MH) in swine, where it segregates with the disease in all MH–prone strains investigated. The same C-to-T exchange in nucleotide position 1840 of the human RYR1 cDNA sequence was found in a few human MH pedigrees. We report a German MH pedigree where in vitro contracture test (IVCT) results and haplotypes of markers for the MHS1/RYR1 region including this base transition have yielded several discrepancies. The MH-susceptible phenotype was defined by IVCT performed according to the European standard protocol. Haplotypes were constructed for markers for the MHS1/RYR1 region on chromosome 19 and include the C1840T base exchange. Discussing the probabilities for a number of hypotheses to explain these data, we suggest that our results may challenge the causative role of this mutation—and possibly the role of the RYR1 gene itself—in human MH susceptibility, at least in some cases.     

Where to Restore Ecological Connectivity? Detecting Barriers and Quantifying Restoration Benefits

Landscape connectivity is crucial for many ecological processes, including dispersal, gene flow, demographic rescue, and movement in response to climate change. As a result, governmental and non-governmental organizations are focusing efforts to map and conserve areas that facilitate movement to maintain population connectivity and promote climate adaptation. In contrast, little focus has been placed on identifying barriers—landscape features which impede movement between ecologically important areas—where restoration could most improve connectivity. Yet knowing where barriers most strongly reduce connectivity can complement traditional analyses aimed at mapping best movement routes. We introduce a novel method to detect important barriers and provide example applications. Our method uses GIS neighborhood analyses in conjunction with effective distance analyses to detect barriers that, if removed, would significantly improve connectivity. Applicable in least-cost, circuit-theoretic, and simulation modeling frameworks, the method detects both complete (impermeable) barriers and those that impede but do not completely block movement. Barrier mapping complements corridor mapping by broadening the range of connectivity conservation alternatives available to practitioners. The method can help practitioners move beyond maintaining currently important areas to restoring and enhancing connectivity through active barrier removal. It can inform decisions on trade-offs between restoration and protection; for example, purchasing an intact corridor may be substantially more costly than restoring a barrier that blocks an alternative corridor. And it extends the concept of centrality to barriers, highlighting areas that most diminish connectivity across broad networks. Identifying which modeled barriers have the greatest impact can also help prioritize error checking of land cover data and collection of field data to improve connectivity maps. Barrier detection provides a different way to view the landscape, broadening thinking about connectivity and fragmentation while increasing conservation options.     

Surgery for hypertrophic cardiomyopathy

Hypertrophic cardiomyopathy (HCM) is a genetically determined cardiac disease characterised by otherwise unexplained myocardial hypertrophy of the left ventricle, and may result in left ventricular outflow tract obstruction. It is the most common cause of sudden cardiac death in young adults due to arrhythmias. Septal myectomy is a surgical treatment for HCM with moderate to severe outflow tract obstruction, and is indicated for patients with severe symptoms refractory to medical therapy. The surgical approach involves obtaining access to the interventricular septum via transaortic, transapical or transmitral approaches, and excising a portion of the hypertrophied myocardium to relieve the outflow tract obstruction. Large, contemporary series from centres experienced in septal myectomy patients have demonstrated a low early mortality of <2 %, excellent long-term survival that matches the general population, and durable relief of symptoms.     

Hemoptysis: Diagnosis and Management

Hemoptysis is one of the most important symptoms of cardiopulmonary disease—first, because bleeding even in small amounts may indicate the presence of such serious diseases as bronchogenic carcinoma or active tuberculosis, and second, because untreated massive hemorrhage is associated with a high mortality rate. The cause of hemoptysis may be suggested by the history, physical examination or chest x-ray findings, but often diagnostic procedures such as bronchoscopy, bronchography and pulmonary angiography are needed for definitive diagnosis. The importance of early localization of the bleeding site and surgical intervention in patients with massive hemoptysis is stressed.     

Activatable G-quadruplex based catalases for signal transduction in biosensing

Discovery of oxidative catalysis with G-quadruplex•hemin constructs prompted a range of exciting developments in the field of biosensor design. Thus, G-quadruplex based DNAzymes with peroxidase activity found a niche as signal transduction modules in a wide range of analytical applications. The ability of nucleic acid scaffolds to recognise a variety of practically meaningful markers and to translate the recognition events into conformational changes powers numerous sensor design possibilities. In this work, we establish a catalase activity of G-quadruplex•hemin scaffolds. Catalase activated hydrogen peroxide decomposition generates molecular oxygen that forms bubbles. Observation of bubbles is a truly equipment free signal readout platform that is highly desirable in limited resources or do-it-yourself environments. We take a preliminary insight into a G-quadruplex structure—folding topology—catalase activity correlation and establish efficient operating conditions. Further, we demonstrate the platform''s potential as a signal transduction modality for reporting on biomolecular recognition using an oligonucleotide as a proof—of—concept target. Ultimately, activatable catalases based on G-quadruplex•hemin scaffolds promise to become valuable contributors towards accessible molecular diagnostics applications.     

Phenotypic plasticity in juvenile jellyfish medusae facilitates effective animal–fluid interaction

Locomotion and feeding in marine animals are intimately linked to the flow dynamics created by specialized body parts. This interaction is of particular importance during ontogeny, when changes in behaviour and scale challenge the organism with shifts in fluid regimes and altered functionality. Previous studies have indicated that Scyphozoan jellyfish ontogeny accommodates the changes in fluid dynamics associated with increasing body dimensions and velocities during development. However, in addition to scale and behaviour that—to a certain degree—underlie the control of the animal, flow dynamics are also dependent on external factors such as temperature. Here, we show phenotypic plasticity in juvenile Aurelia aurita medusae, where morphogenesis is adapted to altered fluid regimes imposed by changes in ambient temperature. In particular, differential proportional growth was found to compensate for temperature-dependent changes in viscous effects, enabling the animal to use adhering water boundary layers as ‘paddles’—and thus economize tissue—at low temperatures, while switching to tissue-dominated propulsion at higher temperatures where the boundary layer thickness is insufficient to serve for paddling. This effect was predicted by a model of animal–fluid interaction and confirmed empirically by flow-field visualization and assays of propulsion efficiency.