All posts by James Crewdson

James Crewdson is a Clinical Medicine student at Imperial College London, having already completed a BA in Biological and Biomedical Science at Gonville and Caius College, University of Cambridge. He has a keen interest in all of biological sciences and in the happenings of Manchester City Football Club, the best team in the land and all the world. You can get in touch with him on Twitter at @JamesCrewdson1.

Is it true that animals can smell cancerous growths?

Endal the incredible dogThe idea that animals can sniff out an illness that has been around for a long time. When it comes to finding cancer, however, scientists certainly don’t turn their noses up at the prospect. It is known that cancerous cells produce their own particular set of chemicals and it is also well known that many animals are particularly sensitive to small changes in airborne substances (dogs’ noses in particular). Anecdotally, there are many stories of dogs and other pets seemingly indicating the presence of a cancer in their owners. But what does the actual evidence say?

Well, so far the published research is conflicted; some studies show that animals may be able to sense cancer while others disagree. Potentially the most positive study so far examined whether a specially-trained Labrador could detect colorectal cancer (bowel cancer) from breath and stool samples (it sounds horrible, I know). The study’s results suggested that the dog’s accuracy was up to an incredible 99%! Other studies, however, have not seen such a remarkable result.

One experiment, for example, that used double-blind tests (a good way of making sure the researchers don’t accidently affect the results) showed that specially trained dogs were no better than random chance at detecting prostate cancer. While a separate study testing dogs’ ability to detect lung cancer detection was a mixed bag of treats: the dogs recognised 80% of the people who had cancer but also poked their noses at a large number of people who did not have cancer, meaning that any benefit was lost due to the very high number of false readings. Overall, the research seems to suggest some animals may be Lassie-like in their ability to recognise cancer but that the technique is not reliable enough for medical purposes.

What about other diseases? Many diseases have distinctive smells. One in particular is Type I diabetes. When a Type I diabetic has low blood sugar, their body creates substances called ketones which can leave the body in the breath. One commercial outfit (Dogs4Diabetics) claims to sell trained dogs that can smell ketones and ‘tell’ the owner when their blood sugar levels are dropping dangerously low – potentially before they would otherwise realise.

Using animals to help diagnose people is an interesting idea and dogs seem to be the top companion for the medic. Who knows, perhaps in the future we might hear from the waiting room: “Mrs Smith, the dogtor will sniff you now”?

Answer by James Crewdson

Photo caption: Endal wearing his PDSA Gold Medal. During a 2001 emergency saved a man, Endal retrieved his mobile phone from beneath the car, fetched a blanket and covered him, and then ran to a nearby hotel to obtain help.

Article by James Crewdson

June 4, 2015

James Crewdson is a Clinical Medicine student at Imperial College London, having already completed a BA in Biological and Biomedical Science at Gonville and Caius College, University of Cambridge. He has a keen interest in all of biological sciences and in the happenings of Manchester City Football Club, the best team in the land and all the world. You can get in touch with him on Twitter at @JamesCrewdson1.


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Why do we “black out” after drinking alcohol?

Alcohol Black OutHow is it possible to “black out” after drinking alcohol – where you can still walk, talk (and perhaps send embarrassing texts) that you don’t recall doing the morning after? Does it have to do with oxygen in the brain?  (via email)

As a “hard-working” student, I feel that I am well placed to answer this question (due to my medical and biochemical studies, not personal experimentations of course). And as I’m sure you’re aware, alcohol affects how well your brain works and, in particular, how well you remember things. While alcohol influences many parts of the brain, some areas are affected more than others.

One part of the brain that does feel the effects of alcohol is called the ‘hippocampus’ – a region crucial for making memories. Seated deep within the brain, it is a place where there are many junctions between nerve cells from many different parts of the brain – a bit like a switchboard for telephone lines. The hippocampus somehow ties information from different parts of the brain together – strengthening junctions – and in doing so helps form memories as events happen.

Interestingly, alcohol affects how well we can make long term memories much more than short term ones. This means that you will be able to remember what drink you ordered, but you won’t be able to remember standing up and singing karaoke the next day.

For a bit more detail: brain signalling at the junctions within the hippocampus relies on a chemical messenger (neurotransmitter) called glutamate, which is detected by a receptor called ‘NMDA’. Alcohol stops the brain cells’ NMDA receptors from working as well as they should, meaning less information is transmitted though the hippocampus and so memories are harder to form.

This is a simple view of what happens as the brain is very complicated and alcohol will affect many different parts in different ways. Let’s just be thankful that we can’t remember the horrors from the night before!

Answered by James Crewdson.

Image credit: Martin Mutch on flickr

Article by James Crewdson

July 24, 2014

James Crewdson is a Clinical Medicine student at Imperial College London, having already completed a BA in Biological and Biomedical Science at Gonville and Caius College, University of Cambridge. He has a keen interest in all of biological sciences and in the happenings of Manchester City Football Club, the best team in the land and all the world. You can get in touch with him on Twitter at @JamesCrewdson1.


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What is the longest someone has been pregnant for?

35 weeks pregnant by Thomas van Ardenne, on FlickrThe current record of the longest ever successful pregnancy goes to Mrs. Beulah Hunter and her daughter Penny from Los Angeles in 1945. While a normal human pregnancy lasts for around 266 days, Mrs. Hunter’s pregnancy lasted for 375 days – a whopping 109 days overdue. Dr. Daniel Beltz of the Los Angeles Methodist Hospital, who treated Mrs. Beulah, confirmed the date when she first tested positive and the date of birth. He was quoted as saying that the excessively long pregnancy was due to the unusually slow development in the uterus. The baby was described as of healthy weight and development and went on to lead a healthy life.

Bear in mind that, as with all records of a medical kind, the validity of this claim is questionable. Some argue that it could be two separate pregnancies adding up to a longer time period. The first could have miscarried and then been directly followed by a successful pregnancy. Another idea is that the date for the start of the pregnancy could be wrong. The date was taken from the missed period prior to testing positive but this could be due to a spontaneously missed period and a false positive test. In 1945, the pregnancy test involved injecting the pregnant woman’s urine into a mouse and observing any hormone-related changes. While this was an effective test, it is less accurate than today’s test and could conceivably have falsely come up positive. If she then got pregnant in the following few weeks, it would appear that the baby had an exceptionally long gestational period. However, these are just hypotheses and we may never know the exact length of the pregnancy.

While that pregnancy was long, it isn’t the longest time between conception itself and birth. In May 2003, a boy and a girl were born 13 years after being conceived. In late 1990, a couple from Jerusalem, who had infertility issues, had some embryos cryogenically frozen for use at a later date. Twelve whole years later, these embryos were implanted in the mother and she gave birth to a boy and a girl, weighing 5 pounds each.

Answer by James Crewdson

Question sent from Fiona West

Image source: Flickr – Thomas van Ardenne

Article by James Crewdson

December 18, 2013

James Crewdson is a Clinical Medicine student at Imperial College London, having already completed a BA in Biological and Biomedical Science at Gonville and Caius College, University of Cambridge. He has a keen interest in all of biological sciences and in the happenings of Manchester City Football Club, the best team in the land and all the world. You can get in touch with him on Twitter at @JamesCrewdson1.


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Why do I sneeze everytime I eat chocolate?

First of all, despite the symptom of sneezing after eating chocolate being fairly common, there isn’t a medical name for it. Therefore, I suggest the name ‘Chocoptarmosis, meaning ‘chocolate-induced sneezing’. You heard it on Guru first (send my Nobel Prize in the post).

Chocolates by Kirti Poddar, on FlickrTo understand chocoptarmosis, we must first briefly discuss sneezing and ‘sun-sneezing’ and why they happen. Normally, when something irritates our nasal hairs (from breathing in dust, say), we sneeze. The nerve that sends messages between the nose and the brain, and brings about the sneeze reflex, is called the trigeminal nerve. As the ‘tri’ in the name suggests, it comes in three parts. Firstly, there is a top part, which covers the eyes and forehead (the upper ophthalmic branch); then there is a middle branch, which covers the nasal area (the maxillary branch); and there is the lower branch, which covers the tongue and jaw (the mandibular branch). Sneezes occur due to activity in the middle part – the maxillary branch. Normally, that is.

Sun-sneezing’ (aka the ‘photic sneeze reflex’) is when staring at bright light causes a sneeze. The exact reason is still unclear but one idea is that the there is a bit of faulty wiring: when bright light is detected by your eye, it should cause activity in the upper branch of the trigeminal nerve – making you blink and forcing the pupils to shrink. In ‘sun-sneezing’, the brain has some crossed wires and the middle branch also gets activated, resulting in a sneeze.

Chocoptarmosis may work in a similar way. The tongue has some connections with the trigeminal nerve and so a similar issue with crossed wires may mean that when the taste of chocolate stimulates the lower mandibular branch, the maxillary branch is also activated – again resulting in a sneeze.

Due to the lack of research into chocoptarmosis (which I think we all agree is a shocking oversight from the pharmaceutical industry), there is no known cure. Fortunately, it’s not particularly serious and you shouldn’t worry about it. Just keep a box of tissues nearby before diving into your box of chocolates.

Question from Jason via Facebook

Answer by James Crewdson

 Footnote from Dr Stu:

There are other unusual causes of sneezes, including sex and sexual arousal. Sexually-induced sneezing is similarly thought to be due to some ‘faulty wiring’. Perhaps there is a connection between this condition and the excitement of eating chocolate…?

Be aware also that sneezing can also be a symptom of a food allergy. Allergies are usually accompanied by other symptoms such as runny nose, puffy face or tongue, a rash and itching. It is always worth getting checked out if there are any problematic symptoms.

Article by James Crewdson

December 12, 2013

James Crewdson is a Clinical Medicine student at Imperial College London, having already completed a BA in Biological and Biomedical Science at Gonville and Caius College, University of Cambridge. He has a keen interest in all of biological sciences and in the happenings of Manchester City Football Club, the best team in the land and all the world. You can get in touch with him on Twitter at @JamesCrewdson1.


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