Formation Of Myeloid Bodies Research Articles

Subcellular Abnormalities of Vestibular Nerve Morphology in Patients With Intractable Meniere's Disease.

Objective: Few studies so far have focused on the retrocochlear lesions in Meniere's disease (MD). This study aims to investigate pathological alterations in the central portion of the vestibular nerve (VN) in patients with intractable Meniere's disease (MD) and to explore retrocochlear lesions and their relationship with disease severity.Methods: Eight MD patients with refractory vertigo received vestibular neurectomy via a retrosigmoid or translabyrinthine approach. Segments of VN were carefully removed and immediately fixed for histopathological examination. Five VN specimens were examined by light microscopy after hematoxylin/eosin staining; three specimens were extensively analyzed using transmission electron microscopy, to identify VN ultrastructural lesions. Correlations between lesions and patient clinical characteristics were examined.Results: Histopathological examination revealed evidence of various types of chronic VN impairment, including the formation of corpora amylacea (CA), axon atrophy, and severe damage to the myelin sheath. Electron microscopy revealed membranous whorls within dilated Schmidt–Lanterman incisures, the formation of myeloid bodies, dysmyelination, and demyelination. Unexpectedly, we observed a positive correlation between the density of CA in VN tissue and the duration of disease, as well as the degree of hearing impairment, independent of age.Conclusion: Our findings indicate that deformation of subcellular organelles in the central portion of the VN is one of the key pathological indicators for the progressive severity and intractability of vertigo and support a vestibular nerve degeneration.

Biogenesis of multilamellar membrane incorporations (myeloid bodies) in the Eolagurus luteus pigmented epithelium.

The study detected common ultrastructure of pigmented epithelium cells of Eolagurus luteus and other mammals and described its features characteristic of this species. Stages of interactions between the pigmented epithelium cells and external segments of retinal rod cells were studied. Migration of the external segments to the apical zone of a pigmented epithelium cell was observed. A pigmented epithelium cell was characterized by the presence of tubular endoplasmic reticulum and electron dense cytoplasm with processes directed to the retina. Multilamellar formations were detected, regarded as the initial stages of the myeloid body formation. These structures were characterized by periodicity of layers of ~4.2 and ~13.3 nm. The periodicity of layers in the formed myeloid body was ~23 nm. Interactions between the external segments and cells of pigmented epithelium, leading to formation of myeloid bodies, and the significance of this process for normal work of retinal elements are discussed.

Cultured proximal cells derived from transgenic mouse provide a model to study drug toxicity

The effects of gentamicin on N-acetyl-beta-D-glucosaminidase (NAG) and acid phosphatase (AcP), two lysosomal enzymes present in proximal renal tubule cells, were studied in the PKSV-PCT cell line derived from proximal convoluted tubules from the kidney of a transgenic mouse carrying SV40 large T antigen under the control of the L-type pyruvate kinase gene. Gentamicin (400 micrograms/ml for 72 hr) did not alter cell viability, but significantly reduced cell growth and favored the formation of myeloid bodies. Gentamicin (50 to 800 micrograms/ml for 72 hr) decreased in a dose-dependent manner the cellular NAG in PKSV-PCT cells and stimulated its secretion by 20 to 60%. Chloroquine (50 to 100 microns) and ammonium chloride (NH4Cl, 30mM), two lysosomotropic amines known to stimulate the secretion of lysosomal enzymes in fibroblasts and macrophages, also stimulated secreted NAG in PKSV-PCT cells. However, the effect of chloroquine was less marked in PKSV-PCT cells than in cultured mouse 3T3 fibroblasts. Gentamicin induced lysosomal alkalinization but, in contrast to chloroquine and NH4Cl, the aminoside strongly stimulated the secretion of AcP. The secretion induced by gentamicin was nonpolarized, since the percentage of secreted NAG significantly increased from both the apical and basal sides of PKSV-PCT cells grown on permeable filters. Thus, these data suggest that gentamicin alters the secretion of NAG and AcP by a non-specific pathway and indicate that the PKSV-PCT cell line is a suitable system to examine the cellular action of drugs in kidney proximal tubule cells.

Attenuation by daptomycin of gentamicin-induced experimental nephrotoxicity.

Previously, daptomycin was shown to reduce tobramycin nephrotoxicity in vivo (D. Beauchamp, M. Pellerin, P. Gourde, M. Pettigrew, and M. G. Bergeron, Antimicrob. Agents Chemother. 34:139-147, 1990; C. A. Wood, H. C. Finkbeiner, S. J. Kohlhepp, P. W. Kohnen, and D. C. Gilbert, Antimicrob. Agents Chemother. 33:1280-1285, 1989). Female Sprague-Dawley rats were treated with saline (NaCl, 0.9%), daptomycin (10 mg/kg of body weight every 12 h, subcutaneously), gentamicin (30 mg/kg/12 h, intraperitoneally) or with a combination of daptomycin plus gentamicin over a 10-day period. Animals were killed 4, 10, and 20 days after the end of treatment. Four days after the end of drug administration, gentamicin and daptomycin levels in the renal cortices of animals treated with the combination of daptomycin and gentamicin were significantly higher than in those of rats given gentamicin or daptomycin alone (P < 0.01). Despite the higher cortical concentrations of gentamicin, rats given the combination of gentamicin and daptomycin had less reduction in renal cortex sphingomyelinase activity, less evidence of regeneration of cellular cortical cells ([3H]thymidine incorporation into cortex DNA), lower creatinine concentration in serum, and less histopathologic evidence of injury than rats given gentamicin alone. By immunogold technique, both daptomycin and gentamicin were localized to the lysosomes of proximal tubular cells, regardless of whether animals received the drugs alone or in combination. Interestingly, myeloid body formation occurred in both those animals given gentamicin alone and those given daptomycin plus gentamicin. No significant changes were observed for all groups between 10 and 20 days after the end of therapy, suggesting that the toxicity of gentamicin was not delayed by the concomitant injection of daptomycin. The results confirm that daptomycin can attenuate experimental gentamicin nephrotoxicity.

A simple morphological method for screening drug-induced lipidosis in cultured blood monocytes.

We have invented a simple screening method of detecting drug-induced lipidosis mor-phologically by using cultured rat blood monocytes. In this method, rat blood is centrifuged in iodinated gradient medium to separate monocytes, and these cells are then incubated on chamber slides. These slides are treated with 4, 4'-Diethylethoxyhexestrol at concentrations of 10-4, 10-5, and 10-6 M for 24 hours. Upon examination, light microscopic examination reveals dark blue granules in the cytoplasm of monocytes by acid hematein stain. Lamellar myeloid body formation can be detected in the electron microscopic specimens prepared with the inverted embedding method. This cultured monocyte system, using chamber slides, is considered to be a suitable tool for screening out potent lipidosis-inducing amphiphilic compounds and to be useful for studying structure-activity relationships, because of the simple and fast processes.

Effect of photoreceptor outer segment disk shedding on myeloid body formation in the retinal pigment epithelium of the leopard frog.

To test the hypothesis that myeloid body (MB) formation results from the shedding of retinal photoreceptor outer segments and the consequent degradation of lipids derived from outer segment disk membranes, the effect of massive outer segment shedding and the disruption of such outer segment shedding on MB formation were examined in the leopard frog. Light entrained frogs were first placed in constant light (700 lux) for 48 hours to inhibit shedding, followed by a 1.5 hours dark priming either in vivo or in vitro, and then returned to light for an additional 4 hours which results in massive outer segment shedding. To serve as a control, the effect of shedding disruption on MB formation was assessed in vivo using light manipulation to inhibit shedding, or mechanical removal of the neurosensory retina in vitro. The results indicate that although the phagosome numbers were clearly elevated in the samples taken from either in vivo or in vitro eye-cup preparations where outer segment shedding had been stimulated, there was no significant concomitant increase in Mbs number over controls kept under constant light for 48 hr or constant light 48 hr plus 1.5 hr in dark, where MBs represent approximately 5% of the total RPE cell area. In contrast, when shedding was interrupted either by removal of the neural retina immediately after in vitro eye-cups were returned to light or by maintaining frogs in dark without light stimulation, the RPE cells contained very few phagosome, yet in both conditions RPE cells showed a two-fold increase in MB area over the shedding-stimulated controls (p = 0.0001).(ABSTRACT TRUNCATED AT 250 WORDS)

Diurnal variation in myeloid bodies of the chick retinal pigment epithelium

Myeloid bodies (MBs) are distinct lamellar regions of the normally branched tubular smooth endoplasmic reticulum of retinal pigment epithelial (RPE) cells. These organelles are present in the retinas of many lower vertebrates. Previous investigations have reported a relationship between outer segment disk shedding and phagocytosis by the RPE, and the formation of MBs. The current morphometric study was undertaken to establish if a temporal relationship existed between MB occurrence and the phagocytosis of shed photoreceptor outer segment tips in the chick retina. We report on the occurrence of phagosomes, MBs, and for the first time, MB precursors (templates) in the RPE over a 24-hr diurnal cycle. Phagosome numbers were observed to be highest within 2 hr following lights on, and again following lights off, while MB precursors were most prevalent at two time points, immediately prior to the times for rod and cone outer segment shedding at lights on and lights off respectively. Traditional MBs of the small (0.06 to 0.239 microns2) and medium (0.24 to 0.99 microns2) variety increased both in size and number from 01:00 hr of a 24 hr time period, with smaller and fewer MBs being present late in the dark part of the diurnal cycle, and larger and more numerous MBs in the later part of the light portion and into the early part of the dark portion of the cycle.(ABSTRACT TRUNCATED AT 250 WORDS)

Early sequential ultrastructural renal alterations induced by 2-bromoethylamine hydrobromide in the Swiss ICR mouse.

Thirty-two male Swiss ICR mice were injected intraperitoneally with 300 mg 2-bromoethylamine hydrobromide/kg body weight, anesthetized, and perfused with glutaraldehyde-paraformaldehyde solution at 5, 15, 30, 60, 90, 120, 150, and 180 minutes after treatment. Eight control mice were injected intraperitoneally with sterile diluent, and one was perfused at each of the same time periods as the treated mice. Proximal tubule epithelial alterations progressed over time from increased secondary lysosome and myeloid body formation to cellular and mitochondrial swelling and eventually cell necrosis. The glomerular, peritubular, and vasa recta capillaries had endothelial cell swelling and desquamation and platelet aggregation. Bromoethylamine nephrotoxicosis in the male Swiss ICR mouse is an ischemic necrosis of the proximal tubules and papilla initiated by endothelial cell damage and makes an excellent model of chemically induced damage to endothelial cells and tubular necrosis.

Myeloid body development in the chick retinal pigment epithelium.

Previous investigations have reported a correlation between outer segment disk phagocytosis by the retinal pigment epithelium (RPE), and the formation of myeloid bodies, which are lamellar specializations of the smooth endoplasmic reticulum of the RPE. To further test the hypotheses that MBs are directly related to the process of outer segment shedding, we have undertaken to study the development of the retinal pigment epithelium in the chick utilizing a morphometric ultrastructural approach with specific attention to the timing of outer segment disk shedding and the formation of myeloid bodies. This study has demonstrated a temporal relationship between the initiation of photoreceptor outer segment disk shedding in the chick embryo and the occurrence of myeloid bodies. We have shown that photoreceptor outer segment disk shedding and phagocytosis by the RPE has been initiated in a substantial proportion of the retina by day 18 of development. Myeloid body formation does not begin until two days later at embryonic day 20, and is preceded by the development within the RPE of flattened areas of the normally tubular SER (templates), which we believe represent the precursors of myeloid body formation. Temporal development of outer segment phagocytosis, lamellar SER (template) occurrence and myeloid body formation are all statistically significant at the 95% level.

The formation of myeloid bodies in retinular cells of the pupal compound eyes of silkworm moths (Bombyx mori) exposed to a constant bright light

Numerous well-developed myeloid bodies are formed in the retinular cells of the compound eyes of pupae (cocoons were removed) of silkworm (Bombyx mori) irradiated with a constant bright light (10 000 lux). Such well-developed myeloid bodies are not usually observed in arthropod compound eyes, and they have been observed only in the retinular cells of lepidopterans reared with carotenoid-deficient diet. In this experiment silkworms were fed normal diet containing carotenoids, therefore the formation of myeloid bodies was caused by the abnormally strong illumination (10 000 lux). The fine structure and morphogenesis of myeloid bodies are discussed.

Biochemical mechanisms of aminoglycoside cell toxicity. II. Accumulation of phospholipids during myeloid body formation and histological studies on myeloid bodies using twelve aminoglycoside antibiotics.

Cultured human skin fibroblasts take up aminoglycoside antibiotics into lysosomes to form myeloid bodies. Gentamicin (GM), one such antibiotic, was taken up until the cellular concentration reached an estimated 64 mM on the 3rd day when cells were incubated with 2 mM gentamicin. The rate of release of intracellular GM was high on the first day of incubation and gradually slowed down over the next 4 d. About 50% of the GM remained in the cells even on longer incubation in GM-free medium, suggesting it may irreversibly bind to cellular components. With myeloid body formation, the cellular phospholipid content increased 1.5 times. Bis(monoacyl-glyceryl)phosphate, which is known as a marker of lysosomal phospholipid, phosphatidylcholine and phosphatidylserine showed 250, 162, and 153% increases, respectively. Sphingomyelin was not accumulated, while lysosomal sphingomyelinase was dramatically inhibited. Of 12 different aminoglycoside antibiotics, paromomycin is the most prominent myeloid body-forming antibiotic. The myeloid body-formation is not directly correlated to human nephrotoxicity. On the other hand, the number of myeloid bodies is well correlated to the affinity to the brush border membrane, suggesting that such aminoglycoside antibiotics are taken up easily through cellular endocytosis. The cytotoxic effects of aminoglycoside antibiotics may be due to by their binding to cellular organelles other than lysosomes.

An electrophysiological freeze fracture assessment of cadmium nephrotoxicity in vitro.

Human proximal tubule cell cultures exposed to doses of cadmium chloride (CdCl2) between 0.05 microgram/ml and 0.5 microgram/ml exhibited alterations in cell membrane structure and transport function. At these Cd concentrations, cell numbers were not significantly altered from control values in either nonreplicating confluent, or actively replicating subconfluent cultures. Transmission electron microscopy revealed few alterations in cultures treated with 0.05 microgram/ml Cd. Tight junctions were intact; organelles and myeloid body formation appeared normal. Freeze fracture analysis confirmed the integrity of the tight junctions as well as increased numbers of vesicles or pits along the lateral cell membrane, indicating increased endocytotic activity. Cells exposed to 0.1 microgram/ml Cd were characterized by decreased numbers of microvilli and inhibited myeloid body formation. Cd doses of 0.5 micrograms/ml elicited nuclear chromatin condensation, fragmented sealing strands in 5 to 10% of the tight junction profiles, sparse microvilli, and inhibited myeloid body formation. Electrophysiologic assessments of transport function by Ussing chamber analysis revealed decreases in transepithelial potentials for all three concentrations, with significant differences at Cd concentrations of 0.5 to 0.1 micrograms/ml. Cells treated with 0.5 micrograms/ml Cd also exhibited slight decreases in electrical resistance, consistent with the minimal fragmentation of sealing strands observed in freeze fracture replicas. Resistance in cultures treated with 0.1 or 0.05 micrograms/ml Cd remained within control values and indicated that drops in potential difference and short circuit current in these cells reflected true alterations in ion transport.

Effect of gentamicin on phospholipid metabolism in cultured rabbit proximal tubular cells

We examined the hypothesis that the accumulation of phospholipid in cells exposed to gentamicin is due to impaired degradation. Experiments were performed in rabbit proximal tubular cells grown in primary culture. Cells exposed to 10(-3) M gentamicin manifested myeloid body formation and a progressive increase in total phospholipid that by day 6 was 44% higher than that of control cells and reflected increases of phosphatidylinositol of 235%, phosphatidylcholine of 60%, phosphatidylethanolamine of 90%, and phosphatidylserine of 55% above control values. Gentamicin impaired the degradation of these phospholipids. The t1/2 of the phospholipid pool labeled with [3H]myoinositol increased 146% from 1.17 (control) to 2.88 days (gentamicin); the t1/2 of the [3H]choline pool increased 34% from 1.77 to 2.38 days; the t1/2 of the [3H]ethanolamine pool increased 57% from 3.14 to 4.93 days; the t1/2 of the [3H] serine pool increased 37% from 6.30 to 8.63 days. Exposure of cells to gentamicin for 2 days also stimulated increased incorporation of [3H]myoinositol (68%) and [3H]ethanolamine (59%) into phospholipid. The data are consistent with the hypothesis that gentamicin inhibits the activity of lysosomal phospholipases that results in the accumulation of phospholipid within the lysosome in the form of myeloid bodies. Increased phospholipid synthesis may represent a compensatory response to the impaired lysosomal degradation of phospholipid. We postulate that the preferential increase of phosphatidylinositol reflects the capacity of the polycationic gentamicin to interact electrostatically with the anionic phosphoinositides and inhibit their turnover.

Mode of protective action of fosfomycin against dibekacin-induced nephrotoxicity in the dehydrated rats.

We studied the mechanism on protective effect of fosfomycin against experimental nephrotoxicity induced by dibekacin. In order to simplify an experimental model, the dehydrated Wistar rats were used, because a single injection of dibekacin at 30 mg/kg induced acute renal failure in the dehydrated rats, characterized by alteration of urinalytic parameters and BUN values, and retarded elimination of dibekacin from blood. When the rats were administered simultaneously with fosfomycin at 120 mg/kg, the rate of elimination was restored almost to normal, accompanied with improvement of the nephrotoxic parameters. However, markedly accelerated elimination over normal one was not observed, indicating that the improved elimination was not the reason of protection but a result of normal kidney function. On the other hand, fosfomycin protected the proximal tubular lysosomes from the injury of aminoglycoside, as evidenced a) in vivo by suppression of myeloid body formation and protection of lysosomal membrane integrity of the rats treated with dibekacin, and b) in vitro by dose-dependent protection of the lysosomal membrane integrity of the kidney cells. A study of structure-protective activity relation revealed that phosphonate anion possessing an epoxy function was important for protection, and that the mechanism of protection differed from the antibacterial mechanism.

Perhexiline maleate toxicity on human liver cell lines.

When added to the culture medium of human liver cell lines, perhexiline maleate induced formation of numerous myeloid bodies containing unicentric or multicentric smooth membranes within a few days. The nine lysosomal enzyme activities studied, except for beta-galactosidase which decreased, remained unchanged. These results indicate that on cultured human liver cells perhexiline maleate has an effect similar to that described on hepatocytes of some patients treated with this drug and suggest that myeloid body formation is not due to impairment of lysosomal enzyme activities.

Ultrastructural changes during cholestasis induced by chlorpromazine in the isolated perfused rat liver

Addition of cholestatic doses of chlorpromazine-HC1 to the perfusate of isolated rat livers produces widespread changes in hepatocyte membrane structure. These findings include a marked increase in intrasinusoidal cytoplasmic bullae, appearance of intracellular vacuoles within hepatocytes at both sinusoidal and biliary poles, dilation of bile canaliculi and evagination of canalicular diverticuli, and the formation of myeloid bodies within hepatocytes. These findings obtained in the bile acid depleted perfused liver may result from physiochemical interactions between chlorpromazine or its metabolites and lipid-protein components of cell membranes, consistent with chlorpromazine's properties as a cationic detergent. They occur independently of the vasoconstrictive effects of chlorpromazine and suggest that chlorpromazine may produce cholestasis by altering hepatocyte membrane function.

Effects of 2,3,7,8-tetrachlorodibenzo-p-dioxin on lipid profiles in tissue of the Fischer rat

Female Fischer 344 rats were given single oral doses of 2,3,7,8-tetrachlorodibenzo- p-dioxin (TCDD), 10, 50 or 100 μg/kg, and sacrificed 1, 3, 10, 14 or 21 days later. The fatty livers caused by a sub-lethal dose of TCDD involved a temporary increase in triglyceride and free fatty acid levels, with a persistent decrease in levels of sterol esters. In contrast, the fatty livers resulting from a lethal dose of TCDD involved a large increase in cholesterol esters and free fatty acids, with little change in triglyceride levels. These changes appeared to result in part from damage sustained by lysosomes. TCDD also altered the lipoprotein composition of the serum, the fatty acid composition of various lipid classes in liver and serum, and the ultrastructure of the liver (formation of myeloid bodies). A rapid, dose-dependent effect of TCDD, was the elevation of levels of organic-soluble fluorescent pigment in the heart. This pigment was found to match a previously characterized fraction of lipofuscins in fluorescence spectrum and chromatographic properties. The relationship of these observations to a possible mechanism of toxicity for TCDD involving radical-induced lipid peroxidation is discussed.

Some properties of myeloid bodies induced in rat liver by an antidepressant drug (maprotiline)

The repeated administration of the antidepressant maprotiline to adult rats caused the formation of myeloid bodies in the liver. In situ and in the cell-free state they were shown by acid phosphatase cytochemistry to represent lysosomes. When cytoplasmic extracts of the livers of control and treated animals were subjected to velocity-centrifugation in shallow sucrose gradients, it was found that after drug treatment the peak activities of a series of acid hydrolases were (reversibly) displaced to lower sucrose densities. This behaviour was most likely related to the accumulation of phospholipid-rich material within the myeloid bodies. The subcellular distribution, the level in mitochondria-rich fractions, and some kinetic parameters of the various acid hydrolase activities were not appreciably altered by the medication. The diminished structure-linked latency of a number of acid hydrolases, the greater susceptibility to the influence of Triton X-100 and to a hypoosmotic environment, and the occurrence of structurally damaged particles indicated that the myeloid bodies are more fragile than the lysosomes of control livers.

Pulmonary changes induced by amphophilic drugs.

Administration of amphophilic drugs to experimental animals causes formation of myeloid bodies in many cell types, accumulation of foamy macrophages in pulmonary alveoli, and pulmonary alveolar proteinosis. These changes are the result of an interaction between the drugs and phospholipids which leads to an alteration in physicochemical properties of the phospholipids. Impairment of the digestion of altered pulmonary secretions in phagosomes of macrophages results in accumulation of foam cells in pulmonary alveoli. Impairment of the metabolism of altered phospholipids removed by autophagy induces an accumulation of myeloid bodies. In summary, administration of amphophilic compounds causes a drug-induced lysosomal disease or generalized phospholipidosis.

Effects of intrauterine copper wire on blastocyst and uterine lysosomes of the rabbit: a cytochemical and ultrastructural study.

Summary. Following the insertion of copper wire into their uterine horns, rabbits were mated and cytochemical and ultrastructural observations carried out on blastocysts and on the left (control) and right (treated) horns of the pregnant uteri. The blastocysts and uterine tissue from the control horns were normal in all respects. Blastocysts obtained from the treated horns on Day 6 of gestation contained numerous membrane-bound vacuoles, identified as lysosomes by acid-phosphatase staining, that contained amorphous material in which the presence of copper was revealed by the rubeanic acid procedure. No blastocysts were recovered from treated horns after Day 6. Significant changes were observed in lysosomes of uterine epithelial cells on Days 6 to 10 of gestation. The effects were localized to the segment of uterus containing the copper wire and involved uptake of copper, autophagy, formation of myeloid bodies and shedding of epithelial cells containing such structures into the uterine lumen. There was evidence to suggest that the entry of copper into blastocyst lysosomes was followed by release of lysosomal enzymes, cellular autolysis and death of the affected cells. In the uterus, the toxic effects of copper appeared to be confined to the epithelial cells, whose detachment from the mucosal surface may constitute a protective mechanism. The early effect of copper on the blastocyst suggests that this is the primary site of action of the metal.