Thymus Gland
Thymus Hyperplasia
Myasthenia Gravis
Salivary Glands
Exocrine Glands
Submandibular Gland
Parotid Gland
Sweat Glands
Sebaceous Glands
Adrenal Glands
Harderian Gland
Thymus Extracts
Thymus Hormones
Analysis of the adult thymus in reconstitution of T lymphocytes in HIV-1 infection. (1/8961)
A key question in understanding the status of the immune system in HIV-1 infection is whether the adult thymus contributes to reconstitution of peripheral T lymphocytes. We analyzed the thymus in adult patients who died of HIV-1 infection. In addition, we studied the clinical course of HIV-1 infection in three patients thymectomized for myasthenia gravis and determined the effect of antiretroviral therapy on CD4(+) T cells. We found that five of seven patients had thymus tissue at autopsy and that all thymuses identified had inflammatory infiltrates surrounding lymphodepleted thymic epithelium. Two of seven patients also had areas of thymopoiesis; one of these patients had peripheral blood CD4(+) T-cell levels of <50/mm3 for 51 months prior to death. Of three thymectomized patients, one rapidly progressed to AIDS, one progressed to AIDS over seven years (normal progressor), whereas the third remains asymptomatic at least seven years after seroconversion. Both latter patients had rises in peripheral blood CD4(+) T cells after antiretroviral therapy. Most patients who died of complications of HIV-1 infection did not have functional thymus tissue, and when present, thymopoiesis did not prevent prolonged lymphopenia. Thymectomy before HIV-1 infection did not preclude either peripheral CD4(+) T-cell rises or clinical responses after antiretroviral therapy. (+info)The mouse Aire gene: comparative genomic sequencing, gene organization, and expression. (2/8961)
Mutations in the human AIRE gene (hAIRE) result in the development of an autoimmune disease named APECED (autoimmune polyendocrinopathy candidiasis ectodermal dystrophy; OMIM 240300). Previously, we have cloned hAIRE and shown that it codes for a putative transcription-associated factor. Here we report the cloning and characterization of Aire, the murine ortholog of hAIRE. Comparative genomic sequencing revealed that the structure of the AIRE gene is highly conserved between human and mouse. The conceptual proteins share 73% homology and feature the same typical functional domains in both species. RT-PCR analysis detected three splice variant isoforms in various mouse tissues, and interestingly one isoform was conserved in human, suggesting potential biological relevance of this product. In situ hybridization on mouse and human histological sections showed that AIRE expression pattern was mainly restricted to a few cells in the thymus, calling for a tissue-specific function of the gene product. (+info)Diverse developing mouse lineages exhibit high-level c-Myb expression in immature cells and loss of expression upon differentiation. (3/8961)
The c-myb gene encodes a sequence specific transactivator that is required for fetal hematopoiesis, but its potential role in other tissues is less clear because of the early fetal demise of mice with targeted deletions of the c-myb gene and incomplete of knowledge about c-myb's expression pattern. In the hematopoietic system, c-Myb protein acts on target genes whose expression is restricted to individual lineages, despite Myb's presence and role in multiple immature lineages. This suggests that c-Myb actions within different cell type-specific contexts are strongly affected by combinatorial interactions. To consider the possibility of similar c-Myb actions could extend into non-hematopoietic systems in other cell and tissue compartments, we characterized c-myb expression in developing and adult mice using in situ hybridization and correlated this with stage-specific differentiation and mitotic activity. Diverse tissues exhibited strong c-myb expression during development, notably tooth buds, the thyroid primordium, developing trachea and proximal branching airway epithelium, hair follicles, hematopoietic cells, and gastrointestinal crypt epithelial cells. The latter three of these all maintained high expression into adulthood, but with characteristic restriction to immature cell lineages prior to their terminal differentiation. In all sites, during fetal and adult stages, loss of c-Myb expression correlated strikingly with the initiation of terminal differentiation, but not the loss of mitotic activity. Based on these data, we hypothesize that c-Myb's function during cellular differentiation is both an activator of immature gene expression and a suppressor of terminal differentiation in diverse lineages. (+info)Thymic selection by a single MHC/peptide ligand: autoreactive T cells are low-affinity cells. (4/8961)
In H2-M- mice, the presence of a single peptide, CLIP, bound to MHC class II molecules generates a diverse repertoire of CD4+ cells. In these mice, typical self-peptides are not bound to class II molecules, with the result that a very high proportion of H2-M- CD4+ cells are responsive to the various peptides displayed on normal MHC-compatible APC. We show here, however, that such "self" reactivity is controlled by low-affinity CD4+ cells. These cells give spectacularly high proliferative responses but are virtually unreactive in certain other assays, e.g., skin graft rejection; responses to MHC alloantigens, by contrast, are intense in all assays. Possible explanations for why thymic selection directed to a single peptide curtails self specificity without affecting alloreactivity are discussed. (+info)Partial purification and properties of porcine thymus lactosylceramide beta-galactosidase. (5/8961)
Porcine thymus lactosylceramide beta-galactosidase was purified by a simple procedure. In the final step of isoelectric focusing the enzyme was separated into two peaks of pI 6.3 (peak I) and 7.0 (peak II), which showed 3,600- and 4,000-fold enhancement of lactosylceramide-hydrolysing activity, respectively. The two peaks had identical mobility on polyacrylamide gel electrophoresis. The apparent molecular weight was 34,000. Neither monosialoganglioside (GM1) nor galactosylceramide was hydrolysed by the purified enzyme fractions. The optimal pH was at 4.6, and sodium taurocholate was essential for the reaction. The apparent Km was 2.3 x 10-5 M. The reaction was stimulated by sodium chloride and linoleic acid, while it was strongly inhibited by Triton X-100 and bovine serum albumin. Galactosylceramide, p-nitrophenyl beta-galactoside, and p-nitrophenol were weak inhibitors. No effects of GM1 and galactose were observed on the hydrolysis of lactosylceramide. (+info)The effects of a t-allele (tAE5) in the mouse on the lymphoid system and reproduction. (6/8961)
Mice homozygous for tAE5, a recessive allele at the complex T-locus, are characterized by their unique short-tailed phenotype as well as by runting and low fertility. Histological and histochemical studies of the lymphoid and reproductive systems disclosed structural changes in the mutant spleen resembling those found in autoimmune conditions. Involution of the mutant thymus was greatly accelerated compared to normal. Necrotic changes occurred during spermiogenesis whereas ovarian structure was normal in mutants. The possible mechanisms of the mutant effects are discussed in the framework of other similar syndromes and the mode of action of alleles at the complex T-locus. (+info)Identification of a subpopulation of lymphocytes in human peripheral blood cytotoxic to autologous fibroblasts. (7/8961)
A naturally occurring subpopulation of human peripheral blood lymphocytes is cytotoxic to autologous and/or allogeneic fibroblasts. The autocytotoxic lymphocytes have a receptor for the third component of complement and for aggregated gamma globulin, do not form rosettes with sheep red blood cells, and are not removed by passage through nylon. The autocytotoxic subpopulation is not present in the thymus and tonsils of normal children or in the peripheral blood of individuals with X-linked agammaglobulinemia. Fibroblast absorption experiments demonstrate that the autocytotoxic cells are "sensitized" to antigens expressed on allogeneic fibroblasts in addition to the antigens expressed on autologous cells. Some normal individuals have a second subpopulation of lymphocytes that may "regulate" the autocytotoxic cells. The relevance of these observations to the murine autocytotoxic cells is discussed. (+info)Antitumor agents. I. Effect of 5-fluorouracil and cyclophosphamide on liver microsomes and thymus of rat. (8/8961)
Effects of antitumor agents on rat liver microsomal drug-metabolizing enzyme activities and thymus lymphocytes were studied in male Wistar rats. High doses of 5-fluorouracil (5-FU) and cyclophosphamide (CP) given parenterally for 6 days caused a partial decrease in whole body weight and the microsomal enzyme content such as cytochrome P-450 and cytochrome b5. Aniline p-hydroxylase and aminopyrine N-demethylase activities also decreased in rats dosed for 5 days decreased compared with the control. Both compounds in the high concentrations produced spectral change of "modified type II". However, the magnitude of the spectral changes observed was independent of the the concentration of substrate added. The addition of NADPH to the microsomes-substrate mixture modified the spectral change. Both drugs caused a considerable decrease in thymus weight and the number of thymus lymphocytes, while the alkaline phosphatase activity was enhanced in 5-FU groups, indicating that the agents cause a significant involution of the thymus. Decrease in the total number of the lymphocytes was greater than that in the blood leucocytes. (+info)The thymus gland is an essential organ of the immune system, located in the upper chest, behind the sternum and surrounding the heart. It's primarily active until puberty and begins to shrink in size and activity thereafter. The main function of the thymus gland is the production and maturation of T-lymphocytes (T-cells), which are crucial for cell-mediated immunity, helping to protect the body from infection and cancer.
The thymus gland provides a protected environment where immune cells called pre-T cells develop into mature T cells. During this process, they learn to recognize and respond appropriately to foreign substances while remaining tolerant to self-tissues, which is crucial for preventing autoimmune diseases.
Additionally, the thymus gland produces hormones like thymosin that regulate immune cell activities and contribute to the overall immune response.
Thymus hyperplasia is a condition where the thymus gland, which is a part of the immune system located in the upper chest beneath the breastbone, becomes enlarged due to an increase in the number of cells. This is different from a tumor, where there is an abnormal growth of cells that can be benign or cancerous.
Thymus hyperplasia can be classified into two types: true hyperplasia and lymphoid hyperplasia. True hyperplasia refers to an increase in the number of thymic epithelial cells, while lymphoid hyperplasia is an increase in the number of lymphocytes (a type of white blood cell) within the thymus gland.
Thymus hyperplasia can occur as a result of various factors, including autoimmune diseases, infections, and certain medications. In some cases, it may not cause any symptoms and may be discovered incidentally during imaging studies or other medical tests. However, in other cases, it may cause symptoms such as cough, chest pain, difficulty breathing, and swallowing.
Treatment for thymus hyperplasia depends on the underlying cause and severity of symptoms. In some cases, no treatment may be necessary, while in others, medications or surgery may be required.
Thymectomy is a surgical procedure that involves the removal of the thymus gland. The thymus gland is a part of the immune system located in the upper chest, behind the sternum (breastbone), and above the heart. It is responsible for producing white blood cells called T-lymphocytes, which help fight infections.
Thymectomy is often performed as a treatment option for patients with certain medical conditions, such as:
* Myasthenia gravis: an autoimmune disorder that causes muscle weakness and fatigue. In some cases, the thymus gland may contain abnormal cells that contribute to the development of myasthenia gravis. Removing the thymus gland can help improve symptoms in some patients with this condition.
* Thymomas: tumors that develop in the thymus gland. While most thymomas are benign (non-cancerous), some can be malignant (cancerous) and may require surgical removal.
* Myasthenic syndrome: a group of disorders characterized by muscle weakness and fatigue, similar to myasthenia gravis. In some cases, the thymus gland may be abnormal and contribute to the development of these conditions. Removing the thymus gland can help improve symptoms in some patients.
Thymectomy can be performed using various surgical approaches, including open surgery (through a large incision in the chest), video-assisted thoracoscopic surgery (VATS, using small incisions and a camera to guide the procedure), or robotic-assisted surgery (using a robot to perform the procedure through small incisions). The choice of surgical approach depends on several factors, including the size and location of the thymus gland, the patient's overall health, and the surgeon's expertise.
Thymus neoplasms are abnormal growths in the thymus gland that result from uncontrolled cell division. The term "neoplasm" refers to any new and abnormal growth of tissue, also known as a tumor. Thymus neoplasms can be benign or malignant (cancerous).
Malignant thymus neoplasms are called thymomas or thymic carcinomas. Thymomas are the most common type and tend to grow slowly, invading nearby tissues and organs. They can also spread (metastasize) to other parts of the body. Thymic carcinomas are rarer and more aggressive, growing and spreading more quickly than thymomas.
Symptoms of thymus neoplasms may include coughing, chest pain, difficulty breathing, or swelling in the neck or upper chest. Treatment options for thymus neoplasms depend on the type, size, location, and stage of the tumor, as well as the patient's overall health. Treatment may include surgery, radiation therapy, chemotherapy, or a combination of these approaches.
Myasthenia Gravis is a long-term autoimmune neuromuscular disorder that leads to muscle weakness. It occurs when communication between nerves and muscles is disrupted at the nerve endings, resulting in fewer impulses being transmitted to activate the muscles. This results in muscle weakness and rapid fatigue. The condition can affect any voluntary muscle, but it most commonly affects muscles of the eyes, face, throat, and limbs. Symptoms may include drooping eyelids (ptosis), double vision (diplopia), difficulty swallowing, slurred speech, and weakness in the arms and legs. The severity of symptoms can vary greatly from person to person, ranging from mild to life-threatening.
The disorder is caused by an abnormal immune system response that produces antibodies against the acetylcholine receptors in the postsynaptic membrane of the neuromuscular junction. These antibodies block or destroy the receptors, which leads to a decrease in the number of available receptors for nerve impulses to activate the muscle fibers.
Myasthenia Gravis can be treated with medications that improve communication between nerves and muscles, such as cholinesterase inhibitors, immunosuppressants, and plasmapheresis or intravenous immunoglobulin (IVIG) to remove the harmful antibodies from the blood. With proper treatment, many people with Myasthenia Gravis can lead normal or nearly normal lives.
Salivary glands are exocrine glands that produce saliva, which is secreted into the oral cavity to keep the mouth and throat moist, aid in digestion by initiating food breakdown, and help maintain dental health. There are three major pairs of salivary glands: the parotid glands located in the cheeks, the submandibular glands found beneath the jaw, and the sublingual glands situated under the tongue. Additionally, there are numerous minor salivary glands distributed throughout the oral cavity lining. These glands release their secretions through a system of ducts into the mouth.
Mammary glands are specialized exocrine glands found in mammals, including humans and other animals. These glands are responsible for producing milk, which is used to nurse offspring after birth. The mammary glands are located in the breast region of female mammals and are usually rudimentary or absent in males.
In animals, mammary glands can vary in number and location depending on the species. For example, humans and other primates have two mammary glands, one in each breast. Cows, goats, and sheep, on the other hand, have multiple pairs of mammary glands located in their lower abdominal region.
Mammary glands are made up of several structures, including lobules, ducts, and connective tissue. The lobules contain clusters of milk-secreting cells called alveoli, which produce and store milk. The ducts transport the milk from the lobules to the nipple, where it is released during lactation.
Mammary glands are an essential feature of mammals, as they provide a source of nutrition for newborn offspring. They also play a role in the development and maintenance of the mother-infant bond, as nursing provides opportunities for physical contact and bonding between the mother and her young.
Exocrine glands are a type of gland in the human body that produce and release substances through ducts onto an external or internal surface. These glands are responsible for secreting various substances such as enzymes, hormones, and lubricants that help in digestion, protection, and other bodily functions.
Exocrine glands can be further classified into three types based on their mode of secretion:
1. Merocrine glands: These glands release their secretions by exocytosis, where the secretory product is enclosed in a vesicle that fuses with the cell membrane and releases its contents outside the cell. Examples include sweat glands and mucous glands.
2. Apocrine glands: These glands release their secretions by pinching off a portion of the cytoplasm along with the secretory product. An example is the apocrine sweat gland found in the armpits and genital area.
3. Holocrine glands: These glands release their secretions by disintegrating and releasing the entire cell, including its organelles and secretory products. An example is the sebaceous gland found in the skin, which releases an oily substance called sebum.
The submandibular glands are one of the major salivary glands in the human body. They are located beneath the mandible (jawbone) and produce saliva that helps in digestion, lubrication, and protection of the oral cavity. The saliva produced by the submandibular glands contains enzymes like amylase and mucin, which aid in the digestion of carbohydrates and provide moisture to the mouth and throat. Any medical condition or disease that affects the submandibular gland may impact its function and could lead to problems such as dry mouth (xerostomia), swelling, pain, or infection.
The parotid gland is the largest of the major salivary glands. It is a bilobed, accessory digestive organ that secretes serous saliva into the mouth via the parotid duct (Stensen's duct), located near the upper second molar tooth. The parotid gland is primarily responsible for moistening and lubricating food to aid in swallowing and digestion.
Anatomically, the parotid gland is located in the preauricular region, extending from the zygomatic arch superiorly to the angle of the mandible inferiorly, and from the masseter muscle anteriorly to the sternocleidomastoid muscle posteriorly. It is enclosed within a fascial capsule and has a rich blood supply from the external carotid artery and a complex innervation pattern involving both parasympathetic and sympathetic fibers.
Parotid gland disorders can include salivary gland stones (sialolithiasis), infections, inflammatory conditions, benign or malignant tumors, and autoimmune diseases such as Sjögren's syndrome.
Sweat glands are specialized tubular structures in the skin that produce and secrete sweat, also known as perspiration. They are part of the body's thermoregulatory system, helping to maintain optimal body temperature by releasing water and heat through evaporation. There are two main types of sweat glands: eccrine and apocrine.
1. Eccrine sweat glands: These are distributed throughout the body, with a higher concentration on areas like the palms, soles, and forehead. They are responsible for producing a watery, odorless sweat that primarily helps to cool down the body through evaporation.
2. Apocrine sweat glands: These are mainly found in the axillary (armpit) region and around the anogenital area. They become active during puberty and produce a thick, milky fluid that does not have a strong odor on its own but can mix with bacteria on the skin's surface, leading to body odor.
Sweat glands are controlled by the autonomic nervous system, meaning they function involuntarily in response to various stimuli such as emotions, physical activity, or changes in environmental temperature.
Sebaceous glands are microscopic, exocrine glands that are found in the dermis of mammalian skin. They are attached to hair follicles and produce an oily substance called sebum, which is composed of triglycerides, wax esters, squalene, and metabolites of fat-producing cells (fatty acids, cholesterol). Sebum is released through a duct onto the surface of the skin, where it forms a protective barrier that helps to prevent water loss, keeps the skin and hair moisturized, and has antibacterial properties.
Sebaceous glands are distributed throughout the body, but they are most numerous on the face, scalp, and upper trunk. They can also be found in other areas of the body such as the eyelids (where they are known as meibomian glands), the external ear canal, and the genital area.
Abnormalities in sebaceous gland function can lead to various skin conditions, including acne, seborrheic dermatitis, and certain types of skin cancer.
The sublingual glands are a pair of salivary glands located in the floor of the mouth, beneath the tongue. They are the smallest of the major salivary glands and produce around 5-10% of the total saliva in the mouth. The sublingual glands secrete saliva containing electrolytes, enzymes (such as amylase), and antibacterial compounds that help in digestion, lubrication, and protection against microorganisms.
The sublingual glands' secretions are released through multiple small ducts called the ducts of Rivinus or minor sublingual ducts, as well as a larger duct called the duct of Wharton, which is a common excretory duct for both sublingual and submandibular glands.
Sublingual gland dysfunction can lead to conditions such as dry mouth (xerostomia), dental caries, or oral infections.
The adrenal glands are a pair of endocrine glands that are located on top of the kidneys. Each gland has two parts: the outer cortex and the inner medulla. The adrenal cortex produces hormones such as cortisol, aldosterone, and androgens, which regulate metabolism, blood pressure, and other vital functions. The adrenal medulla produces catecholamines, including epinephrine (adrenaline) and norepinephrine (noradrenaline), which help the body respond to stress by increasing heart rate, blood pressure, and alertness.
The Harderian gland is a specialized exocrine gland located in many vertebrate species, including birds and mammals. In humans, it is rudimentary and not fully developed. However, in other animals like rodents, lagomorphs (rabbits and hares), and some reptiles, this gland plays a significant role.
The Harderian gland is primarily responsible for producing and secreting lipids, which help to lubricate the eye's surface and the nictitating membrane (third eyelid). This lubrication ensures that the eyes remain moist and protected from dryness and external irritants. Additionally, the secretions of the Harderian gland contain immunoglobulins, which contribute to the animal's immune defense system by providing protection against pathogens.
In some animals, the Harderian gland also has a role in pheromone production and communication. The study and understanding of this gland are particularly important in toxicological research, as it is often used as an indicator of environmental pollutant exposure and their effects on wildlife.
I'm sorry for any confusion, but the term "Thymus Plant" refers to a type of plant and does not have a medical definition. The Thymus plant belongs to the mint family and is commonly used as an herb in cooking. It is known for its small, fragrant leaves and is often used to add flavor to dishes. In some cases, the essential oil from the thymus plant may be used in medicinal products, such as throat lozenges or mouthwashes, due to its antiseptic properties. However, a "Thymus plant" itself does not have a medical definition. If you have any questions about medicinal plants or herbs, I'd be happy to try and help answer those for you!
Salivary gland neoplasms refer to abnormal growths or tumors that develop in the salivary glands. These glands are responsible for producing saliva, which helps in digestion, lubrication of food and maintaining oral health. Salivary gland neoplasms can be benign (non-cancerous) or malignant (cancerous).
Benign neoplasms are slow-growing and typically do not spread to other parts of the body. They may cause symptoms such as swelling, painless lumps, or difficulty swallowing if they grow large enough to put pressure on surrounding tissues.
Malignant neoplasms, on the other hand, can be aggressive and have the potential to invade nearby structures and metastasize (spread) to distant organs. Symptoms of malignant salivary gland neoplasms may include rapid growth, pain, numbness, or paralysis of facial nerves.
Salivary gland neoplasms can occur in any of the major salivary glands (parotid, submandibular, and sublingual glands) or in the minor salivary glands located throughout the mouth and throat. The exact cause of these neoplasms is not fully understood, but risk factors may include exposure to radiation, certain viral infections, and genetic predisposition.
Thymus extracts are pharmaceutical preparations made from the thymus gland, which is a part of the immune system located in the chest behind the breastbone. The thymus gland plays an essential role in the development and maturation of immune cells called T-lymphocytes or T-cells.
Thymus extracts contain various immunomodulatory substances, including thymosins, thymopoietin, and other peptides, that are believed to help regulate and boost the immune system's function. These extracts have been used in medical research and some clinical applications, particularly in patients with weakened immune systems due to conditions such as primary immunodeficiency disorders, cancer, or HIV/AIDS.
It is important to note that the use of thymus extracts remains controversial, and their efficacy and safety have not been fully established. Therefore, they should only be used under the supervision of a healthcare professional.
Thymus hormones, also known as thymic factors or thymic humoral factors, refer to the biologically active molecules secreted by the thymus gland. The two main thymus hormones are thymosin and thymopoietin. These hormones play crucial roles in the differentiation, maturation, and function of T-cells, which are a type of white blood cell responsible for cell-mediated immunity. Thymosin is involved in the maturation of T-cells, helping them to distinguish between self and non-self antigens, while thymopoietin contributes to the differentiation of T-cells into their various subsets and supports their proliferation and activation.
The thymus gland is a primary lymphoid organ located in the upper chest region, anterior to the heart. It plays a critical role in the adaptive immune system, particularly during fetal development and early childhood. The thymus gland begins to atrophy after puberty, leading to a decrease in the production of thymus hormones. This natural decline in thymic function is believed to contribute to the decreased immune response observed in older individuals.
Supplementation with thymus hormones has been explored as a potential therapeutic approach for enhancing immune function in various clinical settings, including immunodeficiency disorders, cancer, and aging. However, more research is needed to fully understand their mechanisms of action and potential benefits and risks.
The parathyroid glands are four small endocrine glands located in the neck, usually near or behind the thyroid gland. They secrete parathyroid hormone (PTH), which plays a critical role in regulating calcium and phosphate levels in the blood and bones. PTH helps maintain the balance of these minerals by increasing the absorption of calcium from food in the intestines, promoting reabsorption of calcium in the kidneys, and stimulating the release of calcium from bones when needed. Additionally, PTH decreases the excretion of calcium through urine and reduces phosphate reabsorption in the kidneys, leading to increased phosphate excretion. Disorders of the parathyroid glands can result in conditions such as hyperparathyroidism (overactive glands) or hypoparathyroidism (underactive glands), which can have significant impacts on calcium and phosphate homeostasis and overall health.