The role of joint biomechanics in determining stretch reflex latency at the normal human ankle

Modulation of stretch reflexes during imposed walking movements of the human ankle. Our overall objectives were to examine the role of peripheral afferents from the ankle in modulating stretch reflexes during imposed walking movements and to assess the mechanical consequences of this reflex activity. Specifically we sought to define the changes in the electromyographic (EMG) and mechanical responses to a stretch as a function of the phase of the step cycle. We recorded the ankle position of a normal subject walking on a treadmill at 3 km/h and used a hydraulic actuator to impose the same movements on supine subjects generating a constant level of ankle torque. Small pulse displacements, superimposed on the simulated walking movement, evoked stretch reflexes at different phases of the cycle. Three major findings resulted: 1) soleus reflex EMG responses were influenced strongly by imposed walking movements. The response amplitude was substantially smaller than that observed during steady-state conditions and was modulated throughout the step cycle. This modulation was qualitatively similar to that observed during active walking. Because central factors were held constant during the imposed walking experiments, we conclude that peripheral mechanisms were capable of both reducing the amplitude of the reflex EMG and producing its modulation throughout the movement. 2) Pulse disturbances applied from early to midstance of the imposed walking cycle generated large reflex torques, suggesting that the stretch reflex could help to resist unexpected perturbations during this phase of walking. In contrast, pulses applied during late stance and swing phase generated little reflex torque. 3) Reflex EMG and reflex torque were modulated differently throughout the imposed walking cycle. In fact, at the time when the reflex EMG response was largest, the corresponding reflex torque was negligible. Thus movement not only changes the reflex EMG but greatly modifies the mechanical output that results.

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Molecular and Biochemical Basis of Minocycline-Induced Hyperpigmentation—The Study on Normal Human Melanocytes Exposed to UVA and UVB Radiation

International Journal of Molecular Sciences ◽

10.3390/ijms22073755 ◽

2021 ◽

Vol 22 (7) ◽

pp. 3755

Author(s):

Jakub Rok ◽

Zuzanna Rzepka ◽

Justyna Kowalska ◽

Klaudia Banach ◽

Artur Beberok ◽

...

Keyword(s):

Uv Radiation ◽

Therapeutic Potential ◽

Melanin Synthesis ◽

Uvb Radiation ◽

Biochemical Basis ◽

Skin Hyperpigmentation ◽

Human Melanocytes ◽

Anti Cancer ◽

Normal Human

Minocycline is a drug which induces skin hyperpigmentation. Its frequency reaches up to 50% of treated patients. The adverse effect diminishes the great therapeutic potential of minocycline, including antibacterial, neuroprotective, anti-inflammatory and anti-cancer actions. It is supposed that an elevated melanin level and drug accumulation in melanin-containing cells are related to skin hyperpigmentation. This study aimed to evaluate molecular and biochemical mechanism of minocycline-induced hyperpigmentation in human normal melanocytes, as well as the contribution of UV radiation to this side effect. The experiments involved the evaluation of cyto- and phototoxic potential of the drug using cell imaging with light and confocal microscopes as well as biochemical and molecular analysis of melanogenesis. We showed that minocycline induced melanin synthesis in epidermal melanocytes. The action was intensified by UV irradiation, especially with the UVB spectrum. Minocycline stimulated the expression of microphthalmia-associated transcription factor (MITF) and tyrosinase (TYR) gene. Higher levels of melanin and increased activity of tyrosinase were also observed in treated cells. Moreover, minocycline triggered the supranuclear accumulation of tyrosinase, similar to UV radiation. The decreased level of premelanosome protein PMEL17 observed in all minocycline-treated cultures suggests disorder of the formation, maturation or distribution of melanosomes. The study revealed that minocycline itself was able to enhance melanin synthesis. The action was intensified by irradiation, especially with the UVB spectrum. Demonstrated results confirmed the potential role of melanin and UV radiation minocycline-induced skin hyperpigmentation.

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Stromal-derived factor 1 and thrombopoietin regulate distinct aspects of human megakaryopoiesis

Blood ◽

10.1182/blood.v96.13.4142 ◽

2000 ◽

Vol 96 (13) ◽

pp. 4142-4151 ◽

Cited By ~ 108

Author(s):

Marcin Majka ◽

Anna Janowska-Wieczorek ◽

Janina Ratajczak ◽

M. Anna Kowalska ◽

Gaston Vilaire ◽

...

Keyword(s):

Protein Kinase ◽

Intracellular Signaling ◽

Phosphatidyl Inositol ◽

Mek Inhibitor ◽

Mitogen Activated Protein Kinase ◽

Proliferative Effect ◽

Normal Human ◽

And Migration ◽

Induced Apoptosis

Abstract The role of the chemokine binding stromal-derived factor 1 (SDF-1) in normal human megakaryopoiesis at the cellular and molecular levels and its comparison with that of thrombopoietin (TPO) have not been determined. In this study it was found that SDF-1, unlike TPO, does not stimulate αIIbβ3+ cell proliferation or differentiation or have an antiapoptotic effect. However, it does induce chemotaxis, trans-Matrigel migration, and secretion of matrix metalloproteinase 9 (MMP-9) and vascular endothelial growth factor (VEGF) by these cells, and both SDF-1 and TPO increase the adhesion of αIIbβ3+ cells to fibrinogen and vitronectin. Investigating the intracellular signaling pathways induced by SDF-1 and TPO revealed some overlapping patterns of protein phosphorylation/activation (mitogen-activated protein kinase [MAPK] p42/44, MAPK p38, and AKT [protein kinase B]) and some that were distinct for TPO (eg, JAK-STAT) and for SDF-1 (eg, NF-κB). It was also found that though inhibition of phosphatidyl-inositol 3-kinase (PI-3K) by LY294002 in αIIbβ3+ cells induced apoptosis and inhibited chemotaxis adhesion and the secretion of MMP-9 and VEGF, the inhibition of MAPK p42/44 (by the MEK inhibitor U0126) had no effect on the survival, proliferation, and migration of these cells. Hence, it is suggested that the proliferative effect of TPO is more related to activation of the JAK-STAT pathway (unique to TPO), and the PI-3K–AKT axis is differentially involved in TPO- and SDF-1–dependent signaling. Accordingly, PI-3K is involved in TPO-mediated inhibition of apoptosis, TPO- and SDF-1–regulated adhesion to fibrinogen and vitronectin, and SDF-1–mediated migration. This study expands the understanding of the role of SDF-1 and TPO in normal human megakaryopoiesis and indicates the molecular basis of the observed differences in cellular responses.

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The Role of Nuclear Factor-kappaB and Melanogenesis in Tumor Necrosis Factor-Alpha-Induced Apoptosis of Normal Human Melanocytes

Skin Pharmacology and Physiology ◽

10.1159/000064536 ◽

2002 ◽

Vol 15 (5) ◽

pp. 321-329 ◽

Cited By ~ 11

Author(s):

Jing Shang ◽

Jürgen Eberle ◽

Christoph C. Geilen ◽

Amir M. Hossini ◽

Lothar F. Fecker ◽

...

Keyword(s):

Tumor Necrosis ◽

Nuclear Factor Kappab ◽

Nuclear Factor ◽

Necrosis Factor Alpha ◽

Human Melanocytes ◽

Normal Human ◽

Factor Alpha ◽

Induced Apoptosis ◽

Necrosis Factor

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Vladimir Viktorovich Bobin: scientist — anatomist, teacher, representative of the medical dynasty.

Shidnoevropejskij zurnal vnutrisnoi ta simejnoi medicini ◽

10.15407/internalmed2021.01.076 ◽

2021 ◽

Vol 2021 (1) ◽

pp. 76-82

Author(s):

I.V. Bobina ◽

◽

V.I. Kravtsova ◽

Keyword(s):

Ukrainian Academy ◽

Human Anatomy ◽

Medical Sciences ◽

National Medical ◽

Normal Human ◽

Medical University ◽

Academy Of Sciences ◽

International Academy ◽

Official Data

The article presents not only the official data on the professor of the Department of Normal Human Anatomy at Kharkiv National Medical University, Academician of the Ukrainian Academy of Sciences of National Progress, Honorary Academician of the International Academy of Integrative Anthropology, Doctor of Medical Sciences Vladimir Viktorovich Bobin, but also the memories of students and relatives of the scientist. Shownthe portrait of an intellectual person, Teacher, a loving father and grandfather, such as Professor V.V. Bobin. In the article, the biography of the scientist is shown against the background of historical events in the country. The role of father Viktor Vladimirovich Bobin and academician Vladimir Petrovich Vorobyov in the formation of the character and scientific interests of V.V. Bobin.

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Role of C-type natriuretic peptide in the function of normal human sperm

Asian Journal of Andrology ◽

10.4103/1008-682x.150254 ◽

2016 ◽

Vol 18 (1) ◽

pp. 80 ◽

Cited By ~ 5

Author(s):

Dong-Hui Huang ◽

Hui Xia ◽

Yao Chen ◽

Ke-Jia Wu ◽

Hu Zhao ◽

...

Keyword(s):

Natriuretic Peptide ◽

Human Sperm ◽

Normal Human

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Polo-like kinase expression in normal human endometrium during the menstrual cycle

Reproduction Fertility and Development ◽

10.1071/rd00023 ◽

2000 ◽

Vol 12 (2) ◽

pp. 59 ◽

Cited By ~ 6

Author(s):

Noriyuki Takai ◽

Tami Miyazaki ◽

Isao Miyakawa ◽

Ryoji Hamanaka

Keyword(s):

Menstrual Cycle ◽

Stromal Cells ◽

Cellular Proliferation ◽

Secretory Phase ◽

Ki 67 ◽

Normal Endometrium ◽

Proliferative Phase ◽

Normal Human ◽

Late Secretory Phase

The enzyme, polo-like kinase (PLK), is a mammalian serine/threonine kinase involved in cell cycle regulation. A great deal of evidence regarding the role of PLK in the cell cycle has been obtained through studies of cultured cells, though little is known about its function or even expression in vivo. The endometrium undergoes rapid proliferation and differentiation under ovarian steroid hormone control during the 28-day cycle. Thus, normal endometrium provides an excellent model in which to study the hormone dependency of PLK expression. In the present study, we examined the features of PLK expression in 20 samples of normal human endometrium during the menstrual cycle. The expression of Ki-67 and proliferating cell nuclear antigen (PCNA) were also examined as markers of proliferation. Immunohistochemical studies showed that PLK staining was detected in the basement membrane of many endometrial glands, stromal cells, and some endothelial cells. The number of PLK-positive endometrial gland cells was significantly higher in the late proliferative phase (19.16% 4.98%) and the early secretory phase (19.28% 4.99%) than in the early proliferative phase (2.60% 2.33%) or the late secretory phase (5.76% 2.16%) (P<0.0001). PLK expression seemed to be correlated with the expression of Ki-67 and PCNA in many endometrial glands and stromal cells particularly in the late proliferative phase, reflecting a role of PLK in cellular proliferation. Nevertheless, in the early secretory phase, at which point the expression of Ki-67 and PCNA decreased in endometrial glands, PLK was strongly expressed. This finding suggests that PLK may have some post-mitotic functions in certain specialized cell types. Although the highest expression of PLK was observed in the late proliferative and the early secretory phases, the expression drastically decreased in the late secretory phase. These findings, taken together, indicate that the expression of PLK in normal endometrium fluctuates over the course of the menstrual cycle, suggesting in turn that PLK is associated with hormone-dependent cellular proliferation and that hormone functions may be involved in its regulation.

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