General Thermography
James Stewart Campbell, M. Nathaniel Mead in Human Medical Thermography, 2023
The thymus gland is located in the anterior chest, in front of the upper portion of the heart and trachea (Figure 10.61). It is proportionally large in infancy but shrinks with age. At puberty, it weighs 30 to 50 grams, and by old age, it typically weighs 5 to 15 grams. The thymus rarely becomes neoplastic, developing into a lymphoma or thymoma. Lymphomas occupying superficial lymph nodes may appear warm on thermographic analysis, but this warmth is not associated with the thymus gland itself.165 Thymomas, on the other hand, may become large enough to become detectable as a warm area in the upper anterior chest, but no studies confirming this have been published. Though some thermographers claim that cool areas over the anterior or posterior upper chest are a sign of “underactive thymus,” this is doubtful because of the small size and normally low metabolic activity of the gland in adulthood. A cool area over the upper sternum may instead be due to the presence of thymic cysts, which may become as large as 4 cm (1.6 in.) in diameter. No studies are available concerning cool areas over the thymus gland. MRI and CAT scans can determine anatomic thymus abnormalities, while hematology can monitor the physiologic and pathologic activity of the gland.166
Thymectomy
Mark Davenport, James D. Geiger, Nigel J. Hall, Steven S. Rothenberg in Operative Pediatric Surgery, 2020
It is well known that the thymus is necessary for the development of cellular immunity and T lymphocytes. However, once past infancy the thymus seems to have little function and removal causes no alterations in immune function of normal individuals. The role of the thymus in MG is now clearly recognized and thymectomy is an established and accepted therapy as part of the overall treatment plan. Myasthenia is an autoimmune disorder of the postsynaptic nicotinic acetylcholine receptor and manifests as weakness and fatigue of skeletal muscles. Ptosis, diplopia, dystonia, and loss of facial expression are often common early findings. More severe symptoms include severe weakness and even respiratory compromise. Initial medical therapy consists of drugs aimed at blocking the effect of antibodies at the neuromuscular junction. First-line drugs are anticholinesterases, such as pyridostigmine and mestinon. Steroids and other immunosuppressants are used in more severe cases. Plasmapheresis has also been used to filter out antibodies to the acetylcholine receptors.
Immune system of the newborn
Prem Puri in Newborn Surgery, 2017
Lymphocyte development occurs along two distinct pathways leading to the production of the two major lymphocyte populations, T-cells and B-cells, which have very different biological effector functions. The thymus is the site of development of T-cells, which are responsible for the range of effector functions collectively termed cell-mediated immunity. Cell-mediated immunity ranges from the release of soluble factors such as cytokines, which regulate the activity of all cells of the immune system, to direct cytopathic effect of cytotoxic lymphocytes on viruses or tumor cells. B-lymphocytes, on the other hand, have a more restricted effector function, confined to the synthesis and secretion of humoral antibodies in each of the immunoglobulin classes, IgG, A, M, D, and E. More recently, B-lymphocytes have been shown to be capable of presenting antigen to T-cells.72 In man, the site of synthesis of B-lymphocytes is the bone marrow.
Lung, Liver and Skin Changes in an Infant with Positive Methamphetamine
Published in Fetal and Pediatric Pathology, 2023
Kunasilan Subramaniam, Hilma bt. Hazmi, Yong Swee Guan, Khairul Anuar bin Zainun
Post mortem examination showed an extensive erythematosus rash involving his lips, left ear, around his neck, extensor surface of his upper limbs and lower limbs, both antecubital fossa, bilateral axillae, inguinal, perineal, gluteal and lower back regions (Fig. 1). He was pale and dehydrated, but there were no visible injuries on his body. He was small for his age. His crown heel length was 61 cm (-3SD), his head circumference was 38 cm (<3rd centile), and he weighed 4650 g (<3SD). On the internal examination, the skin showed translucency due to loss of subcutaneous tissues. The chest cavities contained minimal serous fluid. His right lung weighed 41 g and left lung weighed 33 g (normal weight for lungs combined: 99.7–176 grams). The thymus has involuted. The liver was fatty (Fig. 2). Histologically, the lungs showed fibrinoid necrosis of arterial walls (Fig. 3), and pulmonary congestion, but no hemorrhage. No fibroid necrosis was apparent in other organs. The liver showed predominantly diffuse macrovesicular fatty changes (Fig. 4). Brain sections showed no edema or encephalitis. The histology section of the skin taken from the erythematosus area showed epidermal pallor, parakeratosis, and keratinocyte necrolysis. There was no inflammatory cells infiltration in the epidermis or dermis.
Clinical outcome and predictive factors of postoperative myasthenic crisis in 173 thymomatous myasthenia gravis patients
Published in International Journal of Neuroscience, 2018
Yan Li, Haiyan Wang, Pei Chen, Zhenguang Chen, Chunhua Su, Chuanming Luo, Huiyu Feng, Weibin Liu
Thymectomy represents the standard practice of care in thymomatous MG patients [16] and has an important role in the control of symptoms of MG [17]. However, 3%–30% of myasthenic patients still develop MG crisis after thymectomy [5–10,18]. MG crisis is the most serious life-threatening event in MG patients, results in an exacerbation of symptoms with increased muscle weakness and respiratory deficiency requiring mechanical ventilation support. In our study, we found that over 80% of patients with POMC experienced their first episodes of crises in the first 6 months after thymectomy, 4.0% within 6 months to 1 year and 12.0% after 1 year. This phenomenon was also noted by other researchers [18]. It seems that POMC tended to be less likely to develop with time after thymectomy. Perhaps, autoreactive lymphocytes will gradually be deleted after removal of the thymus. On the other hand, we should note that the POMC in the early postoperative period is likely to be affected by the invasiveness of surgery [6]. On the contrary, the POMC in the late postoperative period should not be affected by the operative invasiveness but by the worsened symptom of MG, which may be triggered by precipitants such as infection and improper use of medications.
Proteome of thymus and spleen reveals that 10-hydroxydec-2-enoic acid could enhance immunity in mice
Published in Expert Opinion on Therapeutic Targets, 2020
Pei Fan, Bin Han, Han Hu, Qiaohong Wei, Xufeng Zhang, Lifeng Meng, Jing Nie, Xiaofeng Tang, Xinyue Tian, Lu Zhang, Liping Wang, Jianke Li
As an immuno-organ, the thymus is responsible for generating and accommodating T cells that engage in immune responses [20]. T cell precursors originate from bone marrow, and migrate to the thymus for maturation [39]. When exposed to CP, T cell proliferation and myeloid cell differentiation could be inhibited, thereby triggering immuno-suppression by lessening T cells in the thymus. T cell proliferation is regulated by multiple cytokines, such as interleukin-4, a potent T cell growth factor [40]. This is also supported by the finding that the GO term of response to interleukin-4 in the thymus is inhibited via CP induction that causes T cell developmental retardation. Mature T cells require being positively and negatively selected in the thymic cortex and medulla, respectively, through complicated and stepwise manners to gain competence in immune response [41]. Cytotoxic T cells, a major T cell type, can directly target and wipe out infected cells within the body [42,43]. Here, pathways of the negative T cell selection and the positive regulation of leukocyte mediated cytotoxicity were attenuated by CP. Interestingly, these T cell involved functions in the thymus were found to be revived by supplementation with 10-HDA in the CP injected mice. This evidence suggests that 10-HDA may be a key role player for T cell proliferation, activation, and cytotoxicity in regaining the thymus weight.
Related Knowledge Centers
- Adaptive Immune System
- Epithelium
- Major Histocompatibility Complex
- Thymocyte
- Heart
- Immune System
- Lymphocyte
- T Cell
- Sternum
- Thymic Involution