https://www.facebook.com/1000945216431914/

Biology - Y, Dhaka (2026)

14/05/2026

Placebo means "I shall please." Nocebo means "I shall harm." Together they describe something medicine has spent decades struggling to account for: sugar pills that genuinely relieve pain and harmless drugs that make people sick anyway.

The placebo side is better documented. Give someone an inert pill and tell them it'll help for a lot of people, it does. Brain imaging shows real endorphin release, not just positive self-report. And the ritual matters: injections outperform pills, branded pills outperform generics, expensive treatments work better than cheap ones. Even open-label placebos produce effects where patients are told upfront they're taking a placebo. That last one is the weird part. It means belief isn't really the mechanism conditioning probably is.

Nocebo gets less attention and is arguably more troubling. Tell someone a harmless pill might cause nausea and a meaningful chunk of them will feel nauseated. In statin trials, the placebo group reports muscle pain at nearly the same rate as people on the actual drug. This breaks informed consent in a specific way: you have to warn patients about side effects, but warning them makes the side effects more likely.

The effects are strongest for pain, nausea, anxiety, and depression places where expectation and physiology overlap. Some doctors now try to use this deliberately, framing side effects more gently, treating the appointment itself as part of the therapy. It doesn't require deception. Somehow it works anyway.

Writer: Arnab Mohanto

15/03/2026

What is CRISPR?
A natural gene editing system found in bacteria and archaea is called CRISPR. Scientists adapted CRISPR as a powerful tool to edit DNA in living organisms. In simple terms, CRISPR works like molecular scissors that can cut DNA at a specific location. It allows scientists to delete, add or modify genes.
The system is mainly composed of:
• CRISPR sequences – repeating DNA segments in bacterial genomes
• Cas proteins – enzymes that cut DNA
• Guide RNA (gRNA) – directs the Cas enzyme to the target DNA sequence

The most commonly used system is CRISPR‑Cas9.

CRISPR was first noticed in 1987 by Japanese scientists in bacteria.
Later, scientists discovered that it acts as a bacterial immune system against viruses. The technology for gene editing was developed in 2012 by Jennifer Doudna and Emmanuelle Charpentier. They received the Nobel Prize in Chemistry for this work.

A CRISPR system has three key components.
• CRISPR Array: This region in bacterial DNA contains:
Repeats – identical DNA sequences
Spacers – fragments of viral DNA captured from past infections
These spacers serve as genetic memory of viruses.
• Guide RNA (gRNA): Guide RNA is a synthetic RNA molecule that directs Cas9 to the correct DNA sequence.
It has two parts:
crRNA (CRISPR RNA) – recognizes target DNA
tracrRNA (trans-activating CRISPR RNA) – binds with Cas9
Scientists often combine them into single guide RNA (sgRNA).
• Cas Protein: The Cas protein acts as molecular scissors.
The most famous enzyme is:
Cas9
Cas9 cuts both strands of DNA at a precise location.

How CRISPR Works?
CRISPR works through three natural stages in bacteria.
• Adaptation (Spacer Acquisition): When a virus infects bacteria, bacterial cell captures a piece of viral DNA. This fragment is inserted into the CRISPR region as a spacer. This acts like a genetic memory of the virus.
• Expression: The CRISPR DNA is transcribed into RNA. This produces: crRNA and tracrRNA. These combine with Cas proteins to form a defense complex.
• Interference: When the same virus attacks again. Guide RNA recognizes viral DNA. Cas9 binds to that sequence. Cas9 cuts the viral DNA. The virus becomes inactive.

Applications of CRISPR
• Medicine: CRISPR can treat genetic diseases such as:Sickle Cell Disease, Cystic Fibrosis, Muscular Dystrophy
• Agriculture: CRISPR can create Disease-resistant crops, Drought-tolerant plants, Nutrient-enhanced crops
• Cancer Research: Scientists use CRISPR to study cancer genesand engineer immune cells to attack tumors.
• Infectious Disease Research: CRISPR can help detect viruses like COVID‑19.

Variants of CRISPR Systems
Different CRISPR systems exist:
• Cas9 helps in DNA cutting
• Cas12 helps in DNA detection
• Cas13 helps in RNA editing
Example:
CRISPR‑Cas12
CRISPR‑Cas13

Scientists are developing advanced techniques such as:
• Base editing
• Prime editing
• CRISPR gene therapy
• CRISPR disease diagnostics
These methods aim to make gene editing even more precise and safe.

Writer: Arnab Mohanto

08/03/2026

The Rise of "Gamer's Thumb" (De Quervain's Tenosynovitis)

1. What is "Gamer's Thumb"?
It is a modern Repetitive Stress Injury (RSI) caused by thousands of rapid micro-swipes on our screens while texting, scrolling, or gaming.

The Reality: The human thumb was built for heavy gripping, not for endless, repetitive swiping on a glass screen!

2. The Anatomy: What’s Actually Breaking?
When you hold your phone and swipe with the same hand, you overwork two main tendons at the base of your thumb:
Abductor Pollicis Longus (APL)
Extensor Pollicis Brevis (EPB)

The Pathology: Constant friction causes inflammation and swelling in the tendon's protective sheath. In the medical world, this painful condition is called De Quervain's Tenosynovitis.

3. The 5-Second Clinical Test
Let’s do a quick clinical check called Finkelstein's Test right now:
Tuck your thumb into your palm.
Wrap your fingers over your thumb to make a fist.
Gently bend your wrist downward (towards your pinky).

Result: If you feel a sharp, shooting pain at the base of your thumb, you are already developing this condition!

4. The OT Solution: Ergonomics & Splinting
As Occupational Therapists, we adapt the environment and the task to heal the injury:

The Golden Rule: Stop one-handed scrolling! Use two hands to distribute the workload and instantly relieve thumb pressure.

The OT Device: We prescribe a Thumb Spica Splint. This immobilizes the lower thumb and wrist, forcing the inflamed tendons to rest while leaving your other fingers free for daily tasks.

5. Quick Daily Rehab
Ice Therapy: Apply ice to the base of the thumb for 10 minutes to reduce acute swelling.

Change the Habit: Give your thumbs a break—use voice-to-text dictation for long messages.

Micro-Breaks: Stop every 30 minutes of screen time to gently stretch your fingers and wrists.

Writer: Rupok Saha

22/02/2026

What is Text Neck?
Text Neck is a modern day Repetitive Stress Injury (RSI). It is caused by prolonged forward head posture while using mobile devices.
The Reality: We are gradually deforming our spines just to look at screens.

The Physics Behind It:
When your head is in a neutral position it weighs about 10–12 lbs. As it tilts forward, the load on the cervical spine increases significantly due to gravity.
• 0° tilt: 10–12 lbs
• 30° tilt: 40 lbs
• 60° tilt: 60 lbs
At 60 degrees, it’s like carrying the weight of an 8 years old child on your neck for several hours a day.

The Health Risks:
1. Short Term Effects
• Neck stiffness
• Radiating pain in the arms
• Tension headache
2. Long-Term Effect
• Cervical Kyphosis: Loss of the natural
cervical curve
• Early Osteoarthritis: Accelerated wear
and tear of spinal discs
• Reduced Lung Capacity: Slouched
posture restricts rib cage expansion,
potentially reducing oxygen intake by up
to 30%

The Occupational Therapy Approach: Smart Ergonomics:
• Eye-Level Rule:Raise the screen to eye level. Do not drop your head to the device.
• 20-20-20 Rule: Every 20 minutes, look at something 20 feet away for 20 seconds.
• Change the Habit:Use voice-to-text and earphones to reduce prolonged static, bent-neck posture.

Writer: Rupok Saha

21/02/2026

Have you ever heard about Hematohidrosis?

Hematohidrosis is a rare clinical condition because of that a person excretes blood or blood tinged fluid through intact skin. It is also called hematidrosis. The bleeding typically occurs from areas which have sweat glands eg. the face, forehead, scalp, palms and trunk. It is considered an extremely rare disorder.

Historical Background:
The condition has been described historically in extreme stress situations. A well known reference is the biblical account of Jesus Christ. Here it is described in the Gospel of Luke as sweating “drops of blood” before crucifixion. In medical literature, early documentation was provided by Leonardo da Vinci. He described soldiers sweating blood under extreme fear.

Pathophysiology
Although the exact mechanism is not fully established. The most accepted theory is:
Vascular Rupture for Extreme Stress :
1. The sympathetic nervous system is activated by severe emotional stress.
2. Dermal capillaries undergo intense vasoconstriction.
3. Sudden rebound vasodilation causes rupture of fragile capillaries surrounding sweat glands.
4. Blood enters the sweat gland ducts.
5. Blood mixes with sweat and appears as red fluid on skin.
This explains why episodes are often associated with Anxiety, Fear, Psychological trauma, Panic attacks.

Alternative Theories
• Platelet dysfunction
• Coagulation abnormalities
• Psychogenic purpura
• Vascular fragility disorder

Characteristics
1. Red or pink fluid comes from intact skin
2. No visible cuts or wounds
3. Duration one minute to hours
4. Often self limiting
Associated Symptoms
• Severe anxiety
• Headache
• Abdominal pain
• Emotional distress

Diagnosis
Hematohidrosis is a diagnosis of exclusion. It means other causes of bleeding must first be ruled out. Laboratory investigations include complete blood count (CBC), platelet count, bleeding time, clotting time and coagulation profile (PT and aPTT). If these are normal, a skin biopsy will rarely be needed. Microscopic examination of the discharged fluid shows red blood cells without any skin damage confirming bleeding through intact skin.

Treatment
There is no standardized treatment protocol because it is rare. Management focuses on the causes.
Beta Blockers:
Beta adrenergic blockers refer particularly to the use of propranolol. It is considered as the most effective therapy. It is reported in the case of hematohidrosis. Propranolol reduces sympathetic nervous system overactivity. Thereby it decreases stress induced vasoconstriction and subsequent capillary rupture around sweat glands. Many published case reports have shown significant reduction or complete cessation of bleeding episodes after using this.

Other Treatment:
1. Anti anxiety Medications
2. Psychotherapy
3. Supportive Care

Awareness Points
Why is awareness important?
• Prevents social stigma
• Reduces fear and misunderstanding
• Avoids misdiagnosis as supernatural or self-harm
• Encourages psychiatric evaluation

Writer: Arnab Mohanto

19/02/2026

What is Botulism?
Botulism is a rare but life-threatening neuroparalytic disease. 'Clostridium Botulinum' is a bacterium which is mainly responsible for botulism.

Characteristics of 'Clostridium Botulism':
• Gram Positive
• Rod Shape
• Obligate Anaerobe
• Forms Spores
• Produces Botulinum Neurotoxin (BoNT)

Types of Botulinum Toxin:
There are 7 serotypes: A, B, C, D, E, F, G
Humans mostly affected by:
Type A
Type B
Type E
Type A is the most severe.

How does infection happen?
There are 4 main types, and each has a different entry pathway.
• Foodborne Botulism: Food is improperly canned. For that anaerobic condition forms. This causes a suitable condition for C. botulism. This is why C. botulinum spores germinate inside the can. Bacteria produce toxin inside food. Person eats preformed toxin. Toxin absorbs from intestine then it enters the bloodstream.
• Infant Botulism: Infant consumes spores. It commonly comes from honey. Immature gut flora cannot suppress spores. Spores germinate inside intestine. Toxin produced internally. Toxin absorbed in body and it causes serious paralysis. Most common in babies under 1 year.
• Wound Botulism: Spores enter deep wound. Anaerobic environment allows germination. Toxin produced in tissue. Toxin enters bloodstream.
• Iatrogenic Botulism: It happens due to excessive therapeutic use of Botox. Overdose or improper injection causes systemic spread.

Toxin Mechanism of Action:
Toxin enters the bloodstream. Then it reaches neuromuscular junction. Then it binds presynaptic cholinergic nerve endings. Enter into neuron. Cleaves SNARE proteins eg. SNAP-25, synaptobrevin, syntaxin. It blocks acetylcholine (ACh) release. For that reason Calcium ion don't release. So muscle can't contract. For that Flaccid paralysis happens. It causes descending paralysis.

Symptoms:
• Double vision
• Slurred speech
• Facial Nerve Paralysis
• Dry Mouth and Throat
• Tachycardia
• Nausea and Vomiting
• Abdominal Distension
• Problem of Urinating
• Muscle Weakness

In Infant:
• Constipation
• Weak cry
• Poor feeding
• Hypotonia
• Drooling
• Respiratory distress

Treatment:
• Heptavalent botulinum antitoxin (HBAT)
•Respiratory Support
• Debridement
• Antibiotics

Infant Treatment:
• Human botulism immune globulin (BIG-IV)

Recovery
• Nerve terminals regenerate slowly
• Recovery may take weeks to months
• Physical therapy often needed

Prevention
• Food Safety: Proper pressure canning. Boil home canned food for 10 minutes before eating. Discard bulging cans.
• Infant Safety: No honey before 1 year
• Wound Safety: Proper would care. Avoid injection drug use.

Writer: Arnab Mohanto

16/02/2026

Antibiotics are chemical substances that kill or inhibit the growth of bacteria. These are used in treatment of bacterial infections.

History of Antibiotics
• Before 20th century, Minor wounds often led to sepsis. Pneumonia, tuberculosis, syphilis were usually fatal diseases. Surgery remains risky and difficult. During childbirth, deaths are common.
• The Accidental Discovery of Penicillin in 1928. Alexander Fleming began this revolution. He noticed that a mold was contaminating his petri dishes. This was killing the bacteria. The mond was "Penicillium notatum". But Fleming couldn’t purify it.
• In the 1940s, two scientists Howard Florey and Ernst Boris Chain made penicillin usable.
• The Golden Age of Antibiotics is from 1940s to 1960s. This period was explosive.
Scientists discovered 'Streptomycin' (first effective treatment for TB), 'Tetracycline', 'Chloramphenicol', 'Erythromycin'.

How Antibiotics Work
Antibiotics work by targeting structures that are unique to bacteria. So they damage bacteria without harming human cells much.
They attack the “weak spots” of bacteria.
There are 5 main mechanisms of Antibiotics:
• Cell Wall Inhibition
• Protein Synthesis Inhibition
• DNA or RNA Inhibition
• Metabolic Pathway Inhibition
• Cell Membrane Disruption
Antibiotics can be:
1. Bactericidal which means it kills bacteria
2. Bacteriostatic which means it stops growth

Why They Don’t Harm Human Cells
Because they target:
• Peptidoglycan cell wall (humans don’t have it)
• 70S ribosomes (different from human 80S)
• Unique bacterial enzymes

Antibiotic Resistance
Antibiotic resistance is the ability of bacteria to survive and multiply despite the presence of an antibiotic. In simple words, the medicine stops working but the bacteria doesn’t. Bacteria are smart in a very scary way. They adapt. There are two main ways by which resistance develops:
• Mutation (Natural Selection): Random genetic mutation occurs. Antibiotic kills normal bacteria. Mutated resistant bacteria survive. They multiply and these cause antibiotic resistant.
• Gene Transfer (Sharing Survival Tricks): Bacteria can transfer resistance genes through conjugation, transformation, transduction. They share resistance files with each other.

Main Mechanisms of Resistance
• Enzyme Production
• Altered Target Site
• Efflux Pumps
• Reduced Permeability
Examples of Resistant Bacteria: MRSA, MULTIDRUG RESISTANT TUBERCULOSIS, CARBAPENEM-RESISTANT ENTEROBACTERIACEAE (CRE).

Why Resistance Is Increasing
• Overuse of antibiotics
• Taking antibiotics for viral infections
• Not completing full course
• Self-medication
• Poor infection control in hospitals

How We Can Prevent It
• Only use antibiotics when prescribed
• Complete the full course
• Do not share antibiotics
• Improve hygiene & vaccination
• Control hospital infection spread
• Responsible use in farming

Antibiotic resistance doesn't mean your body becomes resistant. It means the bacteria becomes resistant of the antibiotic, that helps the bacterium to survive. That’s a common misunderstanding. At last, we need to be careful about using and sincere about the doses.

Writer: Arnab Mohanto

13/02/2026

Colossal Biosciences is working to bring back the woolly mammoth, an elephant-like animal that went extinct thousands of years ago. Instead of cloning, which is impossible with ancient DNA, they aim to create a hybrid elephant with mammoth traits, such as thick fur, large fat layers, and cold-adapted blood, so it can survive in Arctic environments.....

Credit: Beard's Biology

Read the full writing on:

https://www.facebook.com/share/p/17tB2bwcWB/

10/02/2026

Have you ever heard about PCOS?

PCOS means Polycystic O***y Syndrome which is a chronic endocrine metabolic disorder. It's mainly starting in adolescence and affects women ovaries. According to WHO about 10–13% of reproductive age women worldwide are affected by this and about 70% women don't know about the symptoms of PCOS. PCOS is the most common causes of infertility. It also cause hormonal disturbances, ovulatory dysfunction and metabolic abnormalities. There are no true cysts for PCOS, here the cysts mean immature follicles which is not truly cysts. There are mainly three disturbance which is caused by PCOS-
• Hormonal Imbalance
• Ovulatory dysfunction
• Insulin resistance
PCOS is diagnosed if 2 out of 3 are present.

Hormonal Pathaophysiology:
Menstrual cycle is a complex physiological process which creates interactions between the hypothalamus, pituitary gland and ovaries. It's controlled by the hypothalamic–pituitary–ovarian (HPO) axis.
This axis helps in cyclic ovarian follicle development, ovulation and preparation of the endometrium for potential pregnancy. This is a regulatory process. Polycystic o***y syndrome (PCOS) means the disruption of this regulatory network. PCOS creates chronic anovulation, hyperandrogenism and altered ovarian morphology. Understanding the hormonal system of a normal menstrual cycle provides essential information into the pathophysiology of PCOS.

Hormones in the Menstrual Cycle and PCOS:

Mentrual Cycle:There are many section in brain. Main sections which are responsible for menstrual cycle is hypothalamus, pituitary gland. The ovaries also help in mentrual cycle. The hypothalamus releases Gonadotropin releasing hormone(GnRH). GnRH triggers pituitary gland to release Luteinizing hormone (LH) and Follicle-stimulating hormone (FSH). During the early follicular phase, FSH levels rise. FSH stimulates the ovarian follicles for maturation. Granulosa cells within these follicles proliferate and produce estradiol in response to FSH stimulation. Estradiol is type of Estrogen hormone. As the cycle goes forward one follicle becomes dominant due to high sensitivity for FSH. LH is relatively low in the early follicular phase. However when estradiol levels increase sharply near mid cycle, there happens a positive feedback mechanism. This positive feedback induces a rapid and pronounced LH surge. LH surge creates the critical endocrine signal for ovulation. After that it triggers dominant follicle and release the oocyte. LH also supports the luteinization of the ruptured follicle into the corpus luteum. Corpus luteum is the primary source of progesterone during the luteal phase. Granulosa cells of pre antral and small antral follicles secretes Anti-Müllerian hormone (AMH). It reflects the ovarian reserve and regulates follicular recruitment. In a normal cycle, AMH levels remain moderate and relatively stable. It ensures balanced follicular development. During the follicular phase Inhibin B is produced. It provides negative feedback on FSH secretion and prevent over stimulation. Inhibin A is secreted mainly by the corpus luteum during the luteal phase. It serves as an indicator of ovulation and luteal activity. Progesterone remains low throughout the follicular phase but rises sharply after ovulation. It is produced by the corpus luteum. This hormone stabilizes the endometrium and prepares it for potential implantation. If pregnancy doesn't happen, progesterone levels decline. It then initiates menstruation.

PCOS Cycle: Polycystic o***y syndrome (PCOS) means the disruption of normal GnRH secretion. It mainly stimulates LH secretion over FSH. LH level is high but FSH level remains normal or relatively low. This imbalance creates follicular maturation. Although multiple follicles begin to develope. For insufficient FSH there doesn't happen the selection of a dominant follicle. The absence of a sharp LH surge also eliminates the necessary trigger for ovulation. In PCOS, AMH levels are consistently high. It happens due to the accumulation of numerous small antral follicles. High AMH inhibits follicular sensitivity to FSH. Inhibin B secretion is reduced and irregular. It creates granulosa cell dysfunction. More LH overstimulates theca cell. This triggers androgen production. High androgen disturbs estrogen formation. For that proper ovulation doesn't happen. For that corpus luteum does not form. Without corpus luteum progesterone stays low. For that menstrual cycle becomes irregular and ovulation doesn't happen. It increases the risk of endometrial thickening.

PCOS is mainly a hormonal signaling problem. It does not means the loss of ovarian follicles. The ovaries contains many follicles but ovulation doesn't occur due to hormonal imbalance. It causes irregular periods, infertility, acne, excess hair growth and metabolic problems.

Writer: Arnab Mohanto

08/02/2026

Have you ever thought about how we store information in our memory?

Every fact you learn, every face you recognize and every skill you master passes through these stages. There are three steps to memorize anything in our brain. This steps are-
• ENCODING – Taking Information In
• CONSOLIDATION – Making Memory Stable
• RETRIEVAL – Bringing Memory Back

We will describe the whole process.

1. ENCODING:
Encoding is the process by which the brain converts experiences into neural signals. When we receive information from the environment and transmit it to specific sensory areas of the brain then 'Encoding' begins. Than what we need is attention. Attention helps us selecting important information. The selected neurons generate electric impulse. This electric impulse is known as action potential. This action potential travels through neural networks. At synapses neurotransmitters are released. Most important neurotransmitters are glutamate and acetylcholine. The sensory cortex are responsible for this process and the prefrontal cortex helps in attention and focus. The hippocampus initiates memory formation. Without attention encoding is impossible and if encoding doesn't occur, memory will not form.

2. CONSOLIDATION:
After encoding, the brain must store it in a stable form. Here mainly occurs the transfer of information from short term memory to long term memory through structural and functional changes in neural circuits. Then the synaptic plasticity occurs. Synaptic plasticity means the neural connection recognition process. Synapses between neurons become stronger. New receptors and proteins are formed. There is a principle “neurons that fire together, wire together". This principles shows the mechanisms behind this is Long-Term Potentiation (LTP), where repeated activation of the same synapse increases its efficiency. Sleep plays a critical role during this stage. Sleeping helps consolidating and stabilizing newly formed memories. The hippocampus is the gateway of memory. Long term memories are stored in the cerebral cortex. The amygdala adds emotional strength to memories. Mainly memory is stored as physical changes in brain connections, not as files or images.

3. RETRIEVAL:
When we need store information, retrieval begins. Retrieval is the process of accessing stored information. Here stored neural circuits reactivate. It uses the same pathway which has used in encoding. Location, emotions, smells or sounds anything can trigger recall. Interestingly, when a memory is retrieved, it is slightly modified in a process called reconsolidation. It strengthen or update the memory. The prefrontal cortex of brain is involved in retrieval. This is sensory or motor cortical regions. Remembering is not only brings information back but also reinforces and strengthens the memory.

By encoding, storing and retrieving information we keep learning and growing every day.

Writer: Arnab Mohanto

Biology - Y

14/05/2026

15/03/2026

08/03/2026

22/02/2026

21/02/2026

19/02/2026

16/02/2026

13/02/2026

10/02/2026

08/02/2026

Address

Website

Alerts

Shortcuts

Share

Category

Listing takedown request