A structural basis for R- and T-banding: a scanning electron microscopy study

The structure of reverse (R)-banded and telomeric (T)-banded chromosomes was studied by examination of the same chromosomes first in the light microscope (LM) followed by the scanning electron microscope (SEM). This procedure demonstrated a structural basis to both the R- and T-banding techniques. A direct correlation was shown between the LM staining patterns and the structural patterns observed in the SEM. In the R-banded chromosomes the positively stained R-bands, viewed by LM, corresponded to highly fibrous three-dimensional regions in the SEM. The negatively stained R-interbands corresponded to flatter regions from which material appeared to have been extracted. These structural observations strongly support the suggestion that chromosomal material is preferentially lost from the R-interbands with aggregation of fibres in the R-bands. T-banded chromosomes showed a similar structure to the R-banded chromosomes. The positively stained T-bands located at the telomeres corresponded to regions of highly aggregated fibres. The remainder of the chromosome, corresponding to the negatively stained area, had a flattened and extracted appearance. These similarities in morphology between the T- and R-banded chromosomes support the view that T-bands result from a progressive breakdown of the R-banded chromosome structure.     

Single-cell resolved imaging reveals intra-tumor heterogeneity in glycolysis,transitions between metabolic states,and their regulatory mechanisms

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Chain conformation in the collagen molecule.

Quantitative X-ray diffraction data have been collected from stretched kangaroo tail tendon and used to test models for the conformation of the polypeptide chains in the collagen molecule. The magnitude of the unit twist of the molecular helix was estimated to be 107.1 ° ± 0.6 °, which is close to the value expected for a helix with ten units in three turns. The intensity data were used to carry out a linked-atom least-squares refinement of models based on two possible interchain hydrogen bonding schemes suggested by Rich &; Crick (1955, 1961). No stereochemically acceptable solution could be found for the hydrogen bonding scheme of model I, but a stereochemically satisfactory solution was found for the scheme of model II which gave a crystallographic R factor of 0.272.     

Cytochemical reaction for cationic proteins as a marker of primary granules during development in chick heterophilis.

The ammoniacal silver reaction (ASR) for cationic proteins was used as a cytochemical marker for the primary or A granules in the cytoplasm of developing heterophils of chick bone marrow. The presence of the electron-dense particulate reaction product of silver, which is localized in the fully formed rod-shaped A granules, provides a marker by which the A granules could be distinguished from the B granules of similar size and by which the formation and maturation of both granule types could be followed through the developmental stages. Progressive developmental stages were ascertained on the basis of decreasing cell size, increasing condensation and margination of the chromatin, and the number and morphology of the granules; the stages were divided into promyelocyte, myelocyte, metamyelocyte and heterophil. During the promyelocyte stage, the first appearance of the electron-dense, membrane-bound, spherical granules (0.3--1.0 micrometer in diameter) is observed in the vicinity of an extensive Golgi complex. They occur in a cytoplasm containing rough-surfaced endoplasmic reticulum, ribosomal clusters, centrioles, mitochondria, microtubules, as well as the membranes, saccules, vesicles and vacuoles of the Golgi complex. These granules are considered as primary but their presence as the only granule type appears very brief. The ASR reaction product is first detected on the surface of these primary granules in late promyelocytes or myelocytes. The secondary or B granule, devoid of reaction for cationic protein at all stages, appears as a condensing vacuole in promyelocytes, but after some A granules are already present. The vacuole contents condense to form the B granules which are 0.1--0.6 micrometer in diameter, often oval-shaped, and contain a loose filamentous material surrounded by a membrane. Tertiary C granules or lysosomes appear during the myelocyte stage as dense core vesicles (0.1--0.2 micrometer in diameter) negative for cationic protein.     

Socioeconomic variations in responses to chest pain: qualitative study

ObjectiveTo explore and explain socioeconomic variations in perceptions of and behavioural responses to chest pain.DesignQualitative interviews.SettingCommunity based study in Glasgow, Scotland.Participants30 respondents (15 men and 15 women) from a socioeconomically deprived area of Glasgow and 30 respondents (15 men and 15 women) from an affluent area of Glasgow.ResultsResidents of the deprived area reported greater perceived vulnerability to heart disease, stemming from greater exposure to heart disease in family members and greater identification with high risk groups and stereotypes of cardiac patients. This greater perceived vulnerability was not associated with more frequent reporting of presenting to a general practitioner. People from the deprived area reported greater exposure to ill health, which allowed them to normalise their chest pain, led to confusion with other conditions, and gave rise to a belief that they were overusing medical services. These factors were associated with a reported tendency not to present with chest pain. Anxiety about presenting among respondents in the deprived area was heightened by self blame and fear that they would be chastised by their general practitioner for their risk behaviours.ConclusionsImportant socioeconomic variations in responses to chest pain may contribute to the known inequities in uptake of secondary cardiology services. Primary care professionals and health promoters should be aware of the ways in which perceptions of symptoms and illness behaviour are shaped by social and cultural factors.

What is already known on this topic

Socioeconomic variations in rates of angiography and revascularisation existAmong socioeconomically deprived patients with a diagnosis of angina, barriers to accessing services include fear, denial, low expectations, and diagnostic confusion

What this study adds

Perceived vulnerability to heart disease is associated with socioeconomic deprivation and is underpinned by positive family history and identification with high risk groups and stereotypesGreater perceived vulnerability to heart disease does not lead to reported presentation in deprived patientsIllness behaviour is influenced by normalisation of chest pain, comorbidity, and poor experience and low expectations of health care, which are more prominent in deprived patients