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Alcohol under a microscope by Bevshots

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Science, Art and Food

Artist Caren Alpert takes these photographs of food under an electron microscope showing us what is there up close that we rarely get to see: hidden landscapes, patterns and textures.

terra cibus no.12: cake sprinkles

terra cibus no.39: red cabbage

terra cibus no.6: red licorice

terra cibus no.32: shrimp tail

terra cibus no.2: chocolate cake 2

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Shaking Death

In the 1950s and 60s, a fatal epidemic called kuru swept through the South Fore tribe of Papua New Guinea, killing over 1,000 people. Kuru means “shaking death” which is consistent to the first symptoms of the victims: tremors, headaches and loss of motor skills, since the disease affected the cerebellum, which is responsible for co-ordinarting movement. Soon the victims weren’t able to stand or eat, they sometimes lost speech and developed open sores, and then finally died six to twelve months later. It was discovered that the epidemic was linked to the tribe’s ritual of mortuary cannibalism—consuming the brains of the recently deceased. Kuru began to disappear when cannibalism was outlawed, and yet a few cases still occurred up into the 2000s, suggesting that the disease has an incubation period of up to 50 years. Kuru belongs to a class of neurodegenerative diseases that also includes what is commonly known as “Mad Cow Disease,” and is caused by abnormally folded proteins called prions. These proteins are present in all cells in their normal form, but the abnormal ones are infectious agents, able to ‘flip’ other proteins into the abnormal prion shape that then flip others, and on and on like dominoes. They gradually cause nerve cells to degenerate and die—and since nerve cells cannot be replaced, the brain tissue takes on a sponge-like appearance as it slowly dies. So, Kuru was originally caused by the victims consuming infected brain material, which then infected their own brain tissue and turned it to spongy mush.

(Image Credit)

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Guys’ Y chromosomes are functional, evolutionary marvels Once thought to be a piece of junk, new research shows that little variation in the male Y chromosome over time proves that it serves a useful function.

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Neurons

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Scientists have successfully removed the extra copy of chromosome 21 in cell cultures derived from a person with Down syndrome.

The cells of people with the condition contain three copies of chromosome 21 rather than the usual pair.

A triplicate of any chromosome is a serious genetic abnormality called a trisomy. Trisomies account for almost one-quarter of pregnancy loss from spontaneous miscarriages, according to the research team.

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The mature retina contains five classes of neurons: photoreceptors (purple), horizontal cells (yellow), bipolar neurons (green), amacrine cells (pink and blue), and ganglion cells (pink and blue). In this cross section of an adult mouse retina, only a subset of bipolar cells, “the ON bipolar cells” are visible by their expression of GFP (green). The pink and blue speckled striations at the bottom of the image mark the fiber layer, which contains the ganglion cell axons that will form the optic nerve.

By Rachel Wong, University of Washington

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The 6 phases of the cell cycle (from top left) are shown for 2 cells in the embryo of the marine worm Cerebratulus marginatus. Each image is a projection of a 40-80 0.3-μm confocal section: interphase, microtubules are long and diffuse; prophase, chromosomes condense and small asters appear; prometaphase, the nuclear envelope breaks down but the spindle is not yet built; metaphase, chromosomes aligned at the spindle equator; anaphase, sister chromatids separate along the spindle as astral microtubules grow; telophase, cleavage furrow constricts around astral microtubules and the central spindle as 2 nuclei reassemble.

By George von Dassow, University of Oregon

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Things I’m learning at med school: Malaria

Basic facts:

Protozoan disease of the genus Plasmodium.

Transmitted only by female Anopheles mosquitos.

4 main species: P. falciparum, P. vivax. P. ovale and P. malariae (P. knowlesi may also infect humans but rarely does so, more commonly affecting monkeys).

When inside RBCs the parasite consumes intracellular proteins (particularly haemoglobin). As haem is potentially toxic, plasmodium detoxifies it to a biologically inert form (haemozoin), which can be seen as a coloured pigment.

Plasmodium alters the RBC membrane, making it irregular in shape, more antigenic and less deformable.

Mechanism:

Mosquito inoculates plasmodial sporozoites from its salivary glands during a blood meal and motile forms of the parasite are carried rapidly in the bloodstream to the liver where they invade hepatic cells and begin a period of asexual reproduction. An amplification process produces 10,000 – 30,000 daughter merozoites.

Infected liver cells swell and burst, discharging motile merozoites into the bloodstream. RBCs are then invaded and the merozoite takes a ring form known as a trophozoite. The trophozoite multiplies, consumes haemoglobin and fills the RBC; the RBC is now known as a schizont (shown in the image above). When the RBCs rupture, daughter merozoites are released, capable of invading more RBCs and repeating the cycle.

Some parasites may develop into longer-lived gametocytes that can transmit malaria. These may be ingested by another mosquito, which forms a zygote in the insect. It matures and migrates to the salivary glands where it can be transmitted to another human host.

 * * *

In P. vivax and P. ovale, a proportion of the intrahepatic forms remain dormant from 3 weeks – 1 year (or more) before reproduction begins (hypnozoites). These are the cause of relapses that characterise infection with these two species.

In P. falciparum, protuberances appear on the surface of RBCs; a specific type of adhesion protein that mediates attachment to receptors on venular and capillary endothelium (cytoadherence). This can lead to blockage and sequestration of RBCs in vital organs. May also adhere to other infected RBCs (agglutination) or non-infected RBCs (rosetting = decreased deformability). Sequestration allows parasites to develop out of reach of splenic processing and filtration, therefore only younger ring forms of asexual parasites are seen circulating in peripheral blood in P. falciparum, so peripheral parasitsaemia is an underestimated value.

Host response:

Splenic filtration is accelerated (becomes enlarged in later stages).

When schizont ruptures interleukin-1 is released, which causes a fever.

Temperatures exceeding 40◦C damage mature parasites, which synchronise the malarial cycle and if left untreated will present as a tertian fever (except in P. malariae which is quartan).

First symptoms: Fever, malaise, headache, fatigue, abdominal discomfort, muscle aches, nausea, vomiting, orthostatic hypertension. May have: mild anaemia, palpable spleen, slightly enlarged liver, mild jaundice. 

Severe P. falciparum: Cerebral malaria due to sequestration and agglutination. May cause coma. ~20% adult mortality.

Acidosis due to accumulation of organic acids (e.g. lactic acid released from RBCs).

Hypoglycaemia as the liver is not maintaining adequate glucose levels due to failure of hepatic gluconeogenesis. There is also increased glucose consumption by host and parasite.

Other symptoms include anaemia, renal failure, pulmonary oedema, hypotension/shock, haemorrhaging, haemoglobinuria and jaundice.

Diagnosis:

Relies on asexual parasite forms in peripheral blood smears (thick and thin; x1000 oil immersion).

Parasitsaemia expressed as number of parasitised erythocytes per 1000 RBCs.

Antibody stick or card tests can also be used using finger prick blood samples.

Antimalarial Drugs:

Quinidine – Trophozoite stage. Kills gametocytes of P. v, P. o and P. m.

Chloroquine – As above but earlier in the asexual cycle.

Others include amodiaquine, mefloquine, tetra/doxycycline, halofantrine.

Prophylaxis – malarone, chloroquine, doxycycline (these will reduce the incidence of P. f infection but cannot treat it once infected).

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Fixed Neuron

A multi-wavelength, three dimensional, wide-field immunofluorescence image of a fixed neuron. The projection was generated using an extended depth of field algorithm. Cell body labeled for tubulin is shown in blue, F-actin in green, and presynaptic protein in Red. Specimen courtesy of Natalie Dowell-Mesfin BMS-PhD student.

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Scientists Identify New Stem Cells with Therapeutic Potential

The discovery, published in the journal PLOS Biology, offers new opportunities in the treatment of cardiovascular diseases, cancer and many other diseases.

The growth of new blood vessels – angiogenesis – occurs during the repair of damaged tissue and organs in adults. However, malignant tumors also grow new blood vessels in order to receive oxygen and nutrients. As such, angiogenesis is both beneficial and detrimental to health, depending on the context, requiring therapeutic approaches that can either help to stimulate or prevent it. Therapeutics that aim to prevent the growth of new blood vessels are already in use, but the results are often more modest than predicted.

For more than a decade, Prof Petri Salvén of the University of Helsinki and his colleagues have studied the mechanisms of angiogenesis to discover how blood vessel growth could be prevented or accelerated effectively.

“We succeeded in isolating endothelial cells with a high rate of division in the blood vessel walls of mice. We found these same cells in human blood vessels and blood vessels growing in malignant tumors in humans. These cells are known as vascular endothelial stem cells. In a cell culture, one such cell is capable of producing tens of millions of new blood vessel wall cells,” Prof Salvén said.

From their studies in mice, the team was able to show that the growth of new blood vessels weakens, and the growth of malignant tumors slows, if the amount of these cells is below normal. Conversely, new blood vessels form where these stem cells are implanted.

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Incredibly Small: Best Microscope Photos of the Year

(Click each image for short details)

Every year for nearly four decades, Nikon has received hundreds of entries in its Small World microscope photography contest. Every year, the images are more amazing, and this year’s winners — selected from nearly 2,000 submissions — are undoubtedly the best yet.

Super-close-ups of garlic, snail fossils, stinging nettle, bat embryos, bone cancer and a ladybug are among the top images this year. The first place winner (above) shows the blood-brain barrier in a living zebrafish embryo, which Nikon believes is the first image ever to show the formation of this barrier in a live animal.

“We used fluorescent proteins to look at brain endothelial cells and watched the blood-brain barrier develop in real-time,” the winners, Jennifer Peters and Michael Taylor of St. Jude Children’s Research Hospital, in Memphis, said in a press release. “We took a 3-dimensional snapshot under a confocal microscope. Then, we stacked the images and compressed them into one – pseudo coloring them in rainbow to illustrate depth.”

Here are the top 20 photomicrographs from the 38th Nikon Small World competition, selected for their originality, informational content, and visual impact by a panel of scientists, journalists and optical imaging experts. — Continue over at WiredScience

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MRSA colonies on blood agar plate

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Above is an electron micrograph of a cannabis sativa leaf.

Disclaimer: When conducting and even reading scientific research, it’s important to do so removed of pre-conceived social and political biases - take the science at face value. 

Research on the psychoactive drug, cannabis, or marijuana, has been ablaze for some time. An article published by Robert Melamedeon the online Harm Reduction Journal draws the distinction between tobacco smoke (that contains the highly addictive compound, nicotine), and cannabis smoke (which contains the psychoactive, THC). At this point in time, it’s medically established that marijuana, even when smoked, has less severe adverse effects on the human body than tobacco. Yet the question remains - what are the degree of the detrimental effects that cannabis does have, and are there any medically beneficial effects?

Some research points to cannabis killing a variety of cancer types, including lung, breast and prostate, leukemia, lymphoma, skin, and glioma cancers. At the same time, however, a German study found that low THC doses encouraged lung cancer in in-vitro cells. Seemingly contradicting results, no? Just keep in mind that while nicotine and THC are chemically similar, their actual receptors in the human body vary in cell type distribution, which is what ultimately determines the effects on the human body.

… cannabis typically down-regulates immunologically-generated free radical production by promoting a Th2 immune cytokine profile. Furthermore, THC inhibits the enzyme necessary to activate some of the carcinogens found in smoke. In contrast, tobacco smoke increases the likelihood of carcinogenesis by overcoming normal cellular checkpoint protective mechanisms through the activity of respiratory epithelial cell nicotine receptors. Cannabinoids receptors have not been reported in respiratory epithelial cells (in skin they prevent cancer), and hence the DNA damage checkpoint mechanism should remain intact after prolonged cannabis exposure.

I highly recommend this article, which you can read fully here. It gives great insights into cell biology within a biomedical context.

Image: Courtesy of David Scharf, via The Scientist

Article: Melamede, Robert. “Cannabis and tobacco smoke are not equally carcinogenic.” Harm Reduction Journal, 2005. Web. 10 October 2012.

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Introducing my favourite protein: Kinesin! It’s so cute and I really want it as a plushie.

Kinesin is the little orange-y thing that looks like two big feet, walking over a microtubule. The big blue ball it carries is a vesicle full of large molecules that were produced in the center of the cell. Kinesin is a motor protein that carries this vesicle to where the molecules are needed in the cell, e.g. at the membrane. Kinesin’s partner in crime is Dynein that walks the microtubules towards the center of the cell. Especially Kinesin is thought to play an important role in mitosis, meiosis, axonal transport and more.

This gif was made from the brilliant animation made by BioVisions for Harvard University. ‘The Inner Life of the Cell’ is amazing and I think everybody should have seen it at least once in their life to get a better idea how much of a miracle life really is.

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A human sperm encounters an egg, seen via electron microscope.

Image by David Phillips, Visuals Unlimited

(via)

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Molecular Visualizations of DNA - Original High Quality Version (by WEHImovies)