The study of diseases, including their causes and effects.

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Inheritance of Huntington's disease

People with Huntington's disease have HTT genes with more than 37 copies of CAG repeat. The risk of extra copies being generated is higher during sperm formation than during ovum formation. Why is it ...
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percentage of animal diseases caused by bacteria?

I know this is a long shot, but what is the approximate percentage out of all the animal diseases that are caused by bacteria? One of the Q&A websites answer it as 90, but is there any conclusive ...
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Why does type 3 systemic hypersensitivity not lead to shock?

Why does type 3 systemic hypersensitivity not lead to anaphylatic shock or hypovolumic shock, which shows the same features of type 1 systemic hypersensitivity like prolonged inflammation, production ...
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12 views

Do other primates get gallstones?

Which non-human primates actually get gall stones the same as humans? All, some, none? References appreciated! Anecdotes about pet primates with gallstones also welcome if you have any...
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39 views

Spread of malaria from an infected person

If a person is infected with malaria, how can that person be a part of spreading malaria? As in, if a female anopheles mosquito sucks blood out of that infected individual, how is it possible that ...
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14 views

Steppe peoples method for healing horses' wounds

There was a custom among nomadic steppe peoples like Huns or Mongols of putting pieces of saltened meat in wounds of their horses to make them heal faster. Did it work? If so, how? I suppose it has ...
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118 views

How plasma cells switches secreting different Ig classes?

In Type 1 hypersensitivity how do B lymphocytes switch Ig classes, from synthesizing IgG to IgE? What is the mechanism? I studied multiple pathology books, it says the same as for IgG secreting ...
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1k views

What is the difference between fibrogenesis and fibrosis?

Fibrosis is the formation of excess fibrous connective tissue in an organ or tissue in a reparative or reactive process. I used the word "fibrogenesis" as the outcome of acute inflammation (healing). ...
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127 views

What causes the pain when a bone fracture is healing?

Why does a fracture still hurts when it is healing? I understand the pain at the beginning - the bone is not in its place, there is a pressure against the nerves, also the swelling pushes the nerves ...
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41 views

How can rapid growth cancer get nutrients in vivo?

When I was little, before I get into biological studying, I read a news talking about cancer would be totally cured after decades. I still remember that researchers had a theory to claim if they could ...
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83 views

Why does ALS start in middle age?

Amyotrophic lateral sclerosis (ALS) often starts at middle age, but I didn't find any suggestion why. Something seems to trigger the symptoms in middle age. If I am not mistaken, the sporadic ALS is ...
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128 views

How do antibiotics create drug-resistant strains

I've heard for years that low-level use of antibiotics causes the spread of drug-resistant strains of bacteria, but the explanations always fall short. I understand mutations and natural selection, ...
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11k views

Why is weight gain a symptom of Cushing's Syndrome?

Cushing's syndrome results from increased levels of cortisol in the body. Cortisol as I understand it however, promotes the breakdown of glycogen and amino-acids in the process of gluconeogenesis, to ...
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684 views

Why is an HIV infection considered “incurable”?

My biology teacher told me that if one caught HIV, they cannot be cured because it was near to impossible to be completely virus-free. She said this was because HIV keeps on changing its glycoprotein ...
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Why cancer is not a communicable disease?

I have seen this question where the author is asking a question about infectivity of virus. I wish to know why cancer is not a communicable disease?
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40 views

What are the limiting factors of pathogen population size in human populations?

I understand that one limiting factor in non-human animal populations is that increased pathogen populations decrease animal populations from killing them, which decreases the density of the animals, ...
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74 views

Disease causing variants and Hardy-Weinberg Equilibrium

Is it true that many disease causing variants/mutations do not follow Hardy Weinberg Equilibrium? If so, then please elaborate on why this may be true (or not) and provide examples. I am interested ...
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21 views

use of adjuvants and peptides in modern vaccines?

when preparation of modern vaccines we generally use a part of the microbe or the antigen such as polysaccharides to create an effective vaccine against the vaccine. so when the preparation of sub ...
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314 views

What were the symptoms of Phineas Gage after suffering his brain injury?

Phineas Gage was a construction worker who suffered a head injury due to an explosion at a construction site. A metal rod was pushed up his cheek and through his head. I have heard he demonstrated ...
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165 views

Case study and speculations on the brain of Edward Mordake

I am very interested in the case of the man named Edward Mordake who lived in the 19th century. In particular, he had two faces. If you have not heard of this man, please, search this up as there are ...
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18 views

Is disease transmisson through milk consumption or meat consumption considered direct or indirect transmission route?

From an epidemiological point of view, is consumption of raw milk or meat considered as indirect or direct transmission ? Let's take the example of bovine TB. Is consumption of unpasteurized milk ...
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168 views

Do people with congenital analgesia feel cold?

There are a few diseases that cause an insensitivity to pain. This question asks about the relationship between the cold and pain, which got me thinking: Is shivering a response driven by the ...
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130 views

Is it harmful for someone to consume things full of bacteria if they don't get physically sick from the bacteria at all?

Or as another example - what if you touch a surface that's contaminated with potentially pathogenic bacteria (like the ones at ...
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57 views

Does tremor frequency generally increase as Parkinson's disease progresses?

I've been trying to research this question, but most if not all the on-line journals require costly subscription, and the studies that are posted look at tremor frequency with regards to other ...
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Are there any auto-immune diseases caused by T cells not detaching from antigen presenting cells (APCs)?

By not detaching I'm referring to after they have formed an immunological synapse, if they don't ever detach.
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Endogenous PAF inhibitor in metastatic process (?)

When neoplastic cells cause a metastasis, they can create a protective coat of platelets that counterbalances immunitary response. My question is if the coat formed due to PAF can be undone by an ...
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Wolbachia - cytoplasmic incompatibility

I read that cytoplasmic incompatibility in Wolbachia occurs when wolbachia-infected male insects mate with wolbachia-free female insects and produce non-viable offspring. By contrast, ...
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What's the relationship between Drugbank drugs and SMPDB pathways?

In the 'pathway browse' panel SMPDB pathways and their corresponding Drugbank drugs are listed. What are the relationships between the drugs and the pathways? Some listed drugs are not in the ...
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39 views

RNAi in nematode resistant plants

Background : Certain plants have been genetically engineered to have sense-antisense gene of a parasitic nematode. The dsRNA produced by the plant then inactivates the mRNA produced in the nematode, ...
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How does botulinum toxin enter the blood stream from the digestive tract?

To my understanding, large polypeptides such as botulinum toxin cannot pass the intestinal lining intact. How, then, can it enter the bloodstream and cause botulism poisoning?
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Why is the administration of exogenous Anti-D not harmful to the foetus?

Haemolytic disease of the newborn can result from Rhesus incompatibility in utero. In this disease a Rh-ve mother becomes exposed to the antigens of a Rh+ve foetus by fetomaternal haemorrhage causing ...
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186 views

Can a fungus become resistant to a chemical such as Potassium Permanganate?

A friend used potassium permanganate solution to treat tinea on the hands/feet but after some initial success, the tinea seems to be making a comeback. Could the fungus develop resistance to potassium ...
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583 views

By what mechanism does an obstructed bile duct cause excess fat in the stool?

By what mechanism does an obstructed bile duct (for example gallstones) cause steatorrhoea (excess fat in the stool)?
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66 views

Dynamic mutation and huntington's

I read that Huntington's is a disorder caused by dynamic mutations in the DNA, which means that a triplet sequence of DNA changes from generation to generation. Say we have the sequence ATGATGATGATG. ...
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306 views

What kind of fly is this?

I found this dude hanging out in my sink, but he didn't fly away when I put a dish in the sink. Turned out it was dead. The front part looks exactly like a housefly. But, I've never seen the back end ...
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What is the difference between influenza A and B viruses that causes their distinct seasonal patterns?

I recently learned from an answer at health.SE* that influenza B tends to occur later in the season compared to influenza A. According to the graph in that answer, during this year’s flu season the ...
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151 views

What can cause a lump in the middle of the neck? (homework case study) [closed]

What can cause an erythematous, fluctuant, nontender mass in the middle of the neck? Full Case Study: (Its the last of 6 cases and I just can't figure this one out, because of all the possibilities, ...
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330 views

Can people with paralyzed eye muscles see?

As far as I am aware, the saccades of the eye are central to visual perception. If the eye is held still, the human stops seeing, even if light is reaching the retina and the visual pathway is intact. ...
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42 views

Should gene therapy safety protocol include isolation?

In the case of a gene therapy trial where viral vectors are used to deliver genes into mammalian cells, including humans, should biosafety and ethical protocols include isolation of the patient as a ...
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75 views

Liver - Regeneration in Cirrhosis

Liver is the most resilient of the human organ (on par with or next to skin). A very interesting experiment on liver regeneration is here. Even if two-thirds of the liver is removed, the remaining ...
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39 views

What is contiguous premise culling and dangerous contact culling?

I am reading this paper related to FMD (foot and mouth disease) epidemics which occurred in UK. It mentioned about terms like IP (infected premise culling), CP (contiguous premise) and DC (dangerous ...
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122 views

Do distinctions between dry, tickly and chesty coughs have any medical basis?

Background At least in Britain you normally come across distinct kinds of cough medicine "chesty", "dry" and "tickly". Questions Are "chesty", "dry" and "tickly" coughs always due to ...
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175 views

Can leukopenia in a person with an otherwise normal immune system lead to non-infectious diseases in the long-term?

If a person has developed leukopenia as a side-effect of long-term use of anti-convulsant medications and his/her immune system appears normal otherwise (does not get infections any more often than a ...
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1answer
266 views

Can Leptospirosis be spread through human urine

I am wondering if Leptospirosis can be spread via the urine of an infected human individual. All of the sources I have been able to find on the web have stated that the disease is primarily spread ...
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122 views

Congenital blindness due to retinitis pigmentosa - does it exist?

Retinitis pigmentosa (RP) patients typically become blind after a period of years in which their eye sight slowly deteriorates due to photoreceptor degeneration. Generally RP patients develop ...
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192 views

Why do people with Down syndrome get fewer cancers?

I'm coming across some conflicting information regarding the correlation between cancer incidents and trisomy 21. I read a report from nature that discusses how Downs are only a tenth as likely to ...
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1answer
58 views

Detailed mechanism of the cause of diabetes mellitus type 1?

I have read in some texts that diabetes mellitus type 1 is caused by degeneration of beta cells due to our body's own immune reaction.Is it true? Can you explain further how are such types of immune ...
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1answer
189 views

Why is the upper respiratory tract so vulnerable to infections?

Wikipedia has the following statement on its Upper respiratory tract infection page: In United States URIs are the most common infectious illness in the general population. What is it about ...
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Are there anyother method under research for curing rabies? [duplicate]

Why is rabies incurable after onset of symptoms? Although we administer HRIG (lyssa virus antibody) to the patient, why doesn't it work after onset of symptoms? And are there any other successful ...
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In cancer, why do cells duplicate themselves?

In regards to cancer why do cells replicate themselves? If it's a mutation, what kind of mutation would this be classified as?