Increase in Cholesterol Along Human Optic Nerve*

Friede, Reinhard L.; Hu, K. H.

doi:10.1111/j.1471-4159.1967.tb09528.x

Cited by 27 publications

(4 citation statements)

References 14 publications

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“…The dried lipids were taken up in chloroform and separated into their major classes by thin layer chromatography using chloroform-methanol-water (65/25/4, v/v/v) as the developing solvent. Total lipid phosphorus was determined by the method of Bartlett (6) and cholesterol b y the method of Friede and Hu (18). Cerebrosides and sulfatides, as separated by thin layer chromatography, were quantitated by their hexose content as described in a previous publication (1 5).…”

Section: Methodsmentioning

confidence: 99%

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Growth and Development of the Thyroidectomized Ovine Fetus

et al. 1974

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ExtractThyroidectomies were performed through a flank incision and uterotomy on five fetuses of 1-4-year-old Columbia and Columbia Suffolk date-bred ewes of 90-1 1 0 days gestation. The fetuses were killed 19-43 days post-thyroidectomy. Body and organ weights, limb roentgenograms, DNA, RNA, and protein concentrations of selected tissues, cerebral and cerebellar lipid concentrations, and cerebellar cerebroside fatty acid composition were measured and compared with similar measurements in control animals. In the thyroidectomized fetuses mean carcass and lung weights were significantly reduced and wool development was consistently delayed. Extremity x-rays showed a delay in the time of appearance and a decrease in the size of epiphyseal centers. The mean DNA concentration was low in muscle tissue; mean protein concentrations were reduced in cerebellum, heart, lung, thymus, and muscle tissues, while mean total lipid concentration was low in cerebral tissue; the percentage of 18-carbon fatty acids was significantly increased in cerebellar cerebrosides. These results indicate that thyroid hormone deficiency, present during the last trimester of gestation in the ovine fetus, impairs carcass and lung growth, delays bone and skin maturation, inhibits growth in cell size in heart, lung, thymus, and cerebral tissues, and delays myelination in the central nervous system (CNS). SpeculationThe present results, considered with results of other investigations of the effects of thyroid hormone deficiency in fetal and newborn mammals, indicate that hypothyroidism impairs somatic growth, delays bone growth and maturation, delays cell growth and replication in the CNS, and inhibits CNS myelination. The critical period for these effects varies in different species. In the rat this period is postnatal, whereas in the sheep it extends into the third trimester of pregnancy. During pregnancy, carcass growth, bone maturation, and lung maturation are most affected in the sheep; CNS changes are minimal. In man fetal hypothyroidism may produce some delay in bone maturation but somatic growth retardation and signs and symptoms of hypothyroidism are not usually present a t birth. Moreover, as in the sheep, any delay in CNS maturation probably is minimal in utero, since very early postnatal treatment minimizes mental retardation. Thus early diagnosis and treatment of hypothyroidism is necessary and consideration of the possibility of newborn screening would seem appropriate.19, 23). Therefore, it is possible that thyroid hormones are not necessary for normal fetal somatic growth. The effect of intrauterine hypothyroidism on CNS growth and maturation also is not entirely clear. Thus we have conducted studies of body and organ growth and thyroid hormone kinetics in the fetal sheep after thyroidectomy. The kinetic studies, described elsewhere (141, indicated that fetal serum levels of both thyroxine (T4) and triiodothyronine ( T 3 ) are unmeasurable soon after fetal thyroidectomy and that the athyrotic fetus receives minimal quantities of materna...

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Section: Methodsmentioning

confidence: 99%

“…Its chemical properties (for review see Reference 8) and variations of the plasma levels of the factor in different pathologic conditions have been the subject of several studies (e.g., 11,13,18,19,22). For newborn infants, some authors reported low values (1, 3, 7, 23), whereas others have found normal adult levels (6,14,17,21,24).…”

Section: Extractmentioning

confidence: 99%

Growth and Development of the Thyroidectomized Ovine Fetus

et al. 1974

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“…It has been proposed that the number of myelin lamellae in the sheath is directly proportional to the axonal circumference, for example, over the range of 10–80 lamellae in the sciatic and vagus nerves of mice (Friede and Samorajski, 1967), or 18–24 in the optic nerve in humans (Friede and Hu, 1967). A significant amount of myelin membrane has been proposed to increase the axonal membrane resistance and decrease the capacitance, increasing the conduction velocity.…”

Section: The Issue Of Intracellular Communication In Myelinated Schwamentioning

confidence: 99%

Role of Connexin-Based Gap Junction Channels in Communication of Myelin Sheath in Schwann Cells

Cisterna

Arroyo

Puebla

2019

Front. Cell. Neurosci.

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Peripheral nerves have the capacity to conduct action potentials along great distances and quickly recover following damage which is mainly due to Schwann cells (SCs), the most abundant glial cells of the peripheral nervous system (PNS). SCs wrap around an axonal segment multiple times, forming a myelin sheath, allowing for a significant increase in action potential conduction by insulating the axons. Mature myelin consists of compact and non-compact (or cytoplasmic) myelin zones. Non-compact myelin is found in paranodal loops bordering the nodes of Ranvier, and in the inner and outermost cytoplasmic tongues and is the region in which Schmidt-Lanterman incisures (SLI; continuous spirals of overlapping cytoplasmic expansions within areas of compact myelin) are located. Using different technologies, it was shown that the layers of non-compact myelin could be connected to each other by gap junction channels (GJCs), formed by connexin 32 (Cx32), and their relative abundance allows for the transfer of ions and different small molecules. Likewise, Cx29 is expressed in the innermost layer of the myelin sheath. Here it does not form GJCs but colocalizes with K v 1, which implies that the SCs play an active role in the electrical condition in mammals. The critical role of GJCs in the functioning of myelinating SCs is evident in Charcot-Marie-Tooth disease (CMT), X-linked form 1 (CMTX1), which is caused by mutations in the gap junction protein beta 1 ( GJB1 ) gene that codes for Cx32. Although the management of CMT symptoms is currently supportive, there is a recent method for targeted gene delivery to myelinating cells, which rescues the phenotype in KO-Cx32 mice, a model of CMTX1. In this mini-review article, we discuss the current knowledge on the role of Cxs in myelin-forming SCs and summarize recent discoveries that may become a real treatment possibility for patients with disorders such as CMT.

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“…It has been assumed for some time that the diameter of a myelinated nerve fibre does not change along its course. Recent anatomical and biochemical findings (Friede, 1966;Friede & Knoller, 1964;Friede & Samorajski, 1967;Friede & Hu, 1967a, 1967bFriede, Tsutomu & Kuo, 1971;Peters, 1968) obtained on the optic nerve indicate that the lipid content of the myelin sheath decreases from the chiasma to the bulbus oculi, whereas the interstitial tissue-mainly glial cells-seems to increase.…”

Section: Introductionmentioning

confidence: 99%

Morphometric analysis of a fibre system in the central nervous system

Tlreff

Meyer-König

Schlote

1972

Journal of Microscopy

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SUMMARY The authors have studied the size and composition of the rat optic nerve at three points along its course. The relative volume of myelinated nerve fibres increases that of the chiasma, whereas the relative volume of interstitium decreases. The decrease of interstitial volume is mainly related to the decrease of glial cell number. Determination of absolute volumes of myelinated fibres and interstitium shows that the volume changes are due to two factors: (a) From the eyebulb to the intermediate portion the interstitial volume decreases, whereas the absolute volume of myelinated fibres remains constant. (b) From the intermediate portion to the chiasma the volume of myelinated fibres increases significantly, whereas the further decrease of interstitial volume is small. The diameter of nerve cross‐section is significantly smaller in the intermediate portion of the optic nerve than near the eyebulb and the chiasma. Here the nerve passes the canalis opticus. The density of glial cells decreases from eyebulb to the chiasma as does the density of pericytes and endothelial cells. The latter makes up only 2·3–3·9% of the density of cells in the interstitial space. The mean volume of a glial cell remains constant at about 1260 μm3 along the path of the optic nerve from eyebulb to chiasma. The number of myelinated nerve fibres is also constant along the path of the optic nerve. There are 107,000 ± 6900 fibres.

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Increase in Cholesterol Along Human Optic Nerve*

Cited by 27 publications

References 14 publications

Growth and Development of the Thyroidectomized Ovine Fetus

Growth and Development of the Thyroidectomized Ovine Fetus

Role of Connexin-Based Gap Junction Channels in Communication of Myelin Sheath in Schwann Cells

Morphometric analysis of a fibre system in the central nervous system

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