SCIENTIFIC ILLUSTRATION: Nucleosome
The Mediterranean Institute for Life Sciences
High resolution ray-traced model of a nucleosome, isolated on black.
A nucleosome is the basic unit of DNA packaging in eukaryotes, consisting of a segment of DNA wound in sequence around four histone protein cores. This structure is often compared to thread wrapped around a spool.
Nucleosomes form the fundamental repeating units of eukaryotic chromatin, which is used to pack the large eukaryotic genomes into the nucleus while still ensuring appropriate access to it. In mammalian cells approximately 2 m of linear DNA have to be packed into a nucleus of roughly 10 µm diameter.
Nucleosomes are folded through a series of successively higher order structures to eventually form a chromosome; this both compacts DNA and creates an added layer of regulatory control, which ensures correct gene expression.
Knitted Heart - Kevin Hsiu
An anatomically correct heart depicted in the style of embroidery.
Volume Rendering of an ECG gated I.V. contrast enhanced thoracic CT angiography. Pictured above is the lung. The lung shows several small emphysematous bullae.
Systemic sclerosis (SSc) is a systemic autoimmune disease that is characterised by endothelial dysfunction resulting in a small-vessel vasculopathy, fibroblast dysfunction with resultant excessive collagen production and fibrosis, and immunological abnormalities. The classification of SSc is subdivided based on the extent of skin involvement into diffuse cutaneous sclerosis (dcSSc), limited cutaneous sclerosis (lcSSc) or SSc sine scleroderma. While virtually any organ system may be involved in the disease process, fibrotic and vascular pulmonary manifestations of SSc, including interstitial lung disease (ILD) and pulmonary hypertension (PH), are the leading cause of death. As new therapies targeting these pulmonary conditions emerge, early recognition of lung involvement is essential for the care of these patients.
Ayerza’s disease, or black cardiac disease
A condition characterised by asthma, bronchitis, and cyanosis—hence its name—causing secodary polycythemia, dyspnea, emphysema, fibrosis, pulmonary arterial sclerosis, right ventricular dilation/hypertrophy, finger clubbing, hepatosplenomegaly, and reactive bone marrow.
In the history of research on pulmonary hypertension, one of the key landmarks was the clinical description of the disease, which was made in 1901 by Abel Ayerza.
From then on, in the international medical literature (especially the French, British and American literature), so-called “Ayerza’s disease” encompassed various aetiological forms of pulmonary hypertension, discriminated today thanks to developments in the understanding of this disease and its current classification.
Abel Ayerza was born in Buenos Aires, Argentina, in 1861. After achieving a doctorate with a gold medal in 1886 from the School of Medicine at the University of Buenos Aries, he travelled to Paris, France where he specialised with Jean Martin Charcot and François Joseph Babinski at the Hôpital de la Salpêtrière, Pierre Carl Edouard Potain at the Hôpital de la Charité and François Sigismond Jaccoud at the Hôpital de la Pitié. On his return to Argentina, he joined the Hospital de Clínicas at the University of Buenos Aires, where, at the age of 37, he was appointed Professor of the First Chair of Medicine.
On August 20, 1901, Dr Ayerza described a patient with a history of chronic cough and sputum, dyspnoea, severe cyanosis, profound daytime sleepiness and manifestations of right heart failure. The patient was a 38-yr-old male who had suffered from pneumonia at 20 and 32 yrs of age and since then had had respiratory symptoms. Dyspnoea was severe at rest and there was central cyanosis, clubbed fingers and tachypnea. In the respiratory examination, wet crackles and wheezing were abundant in both lungs. In the cardiovascular examination there was jugular venous distension, hepatomegaly, hepatojugular reflux, ascites and oedema of lower limbs. The patient’s blood pressure was 150 mmHg with the Potain apparatus (at that time diastolic blood pressure was not determined) and heart rate was 112 beats per min. The laboratory examination revealed polycythemia of 6,560,000 red blood cells per mm3 and white blood cells were 5,250 cells per mm3.
The patient died 24 days after admission and the autopsy showed dilated bronchi with thickened walls and abundant secretions. The heart was enlarged, weighing 480 g, the right ventricular wall was thickened, the right atrium was dilated, the tricuspid valve ring was normal, the left atrium and ventricle were normal, the valves had no injuries and histological examination of the arteries showed hyperplasia of the middle layer and of the intima with the thrombus obstructing the lumen and, in some cases, newly formed channels.
This clinical picture was different from entities known at that time. In order to differentiate it from other diseases Dr Ayerza called it “cardíaco negro” (black cardiac) due to the extreme degree of cyanosis observed in these patients. Following this announcement, several publications about the disease were initiated in Argentina.
In 1912, Dr Ayerza and his student F.C. Arrillaga proposed that injury of the pulmonary artery was secondary to chronic lung processes and that sclerosis of the pulmonary artery would cause right heart hypertrophy. In the long-term, the impact of mechanical circulatory disturbances on a predisposed arterial tree would bring about the diffuse thickening of the pulmonary artery, which was the histopathological substrate of the “black cardiac”.
In his doctoral thesis, F.C. Arrillaga selected a group of 11 patients with similar characteristics, including the description of the patient presented by Dr Ayerza. In his thesis, although there were some common findings, the aetiology of pulmonary hypertension was not the same in all cases. In 1913, F.C. Arrillaga published a review of the aetiology, pathogenesis, pathology, symptomatology, radiology, evolution, prognosis and treatment of the disease.
As a result of these publications the disease became known worldwide as “Ayerza’s disease”. In the 34th Annual Meeting of the American Society for Medicine in 1919, WARTHIN described the first case in English and recognised in the USA: “A case of Ayerza’s disease: chronic cyanosis, dyspnoea, and erythremia associated with syphilitic arteriosclerosis of the pulmonary artery.”
It was only in 1951 that DRESDALE haemodynamically identified “primary” pulmonary hypertension and gave it the name that was used for many years until it was changed to the current name of “idiopathic” pulmonary arterial hypertension. What Dr Ayerza described in 1901, when there was no chest radiograph or electrocardiogram, let alone cardiac catheterisation, and when laboratory contributions were still precarious, was probably what is now known as severe pulmonary hypertension in a patient with pulmonary parenchymal disease, and it was his student, F.C. Arrillaga, who established that the disease could occur as primary lesions of pulmonary vessels without pulmonary pathology.
Atelectasis is a collapse of lung tissue affecting part or all of one lung. This condition prevents normal oxygen absoption to healthy tissues.
Causes and symptoms
Un interesante video sobre lo que vimos hoy en el hospital: Atelectasia.