Heart rate variability in patients with familial amyloid polyneuropathy

The purpose of this study was to evaluate heart rate variability (HRV) in patients with familial amyloid polyneuropathy (FAP) using the time- and frequency-domain analysis. The study population consisted of 19 patients with FAP, and 19 age and sex matched normal volunteers. The 24-hour Holter recordings of all subjects in sinus rhythm and off medication were analyzed. Five time-domain indices of HRV were computed. The frequency component of HRV was calculated by fast Fourier transform analysis of the RR intervals. The power spectrum of the low frequency (LF) between 0.04-0.15 Hz and high frequency (HF) between 0.15-0.40 Hz and the LF/HF ratio was calculated. Global measures of HRV including the standard deviation of the mean of RR intervals (SDNN) and the standard deviation of 5-minute mean RR intervals (SDANN) were decreased in patients with FAP. Specific vagal influences on HRV including the proportion of RR intervals more than 50 milliseconds different (pNN50) and the HF power on spectral analysis were less in patients with FAP. LF power and LF/HF ratio were more decreased in patients with FAP at the advanced stage than at the early stage. In conclusion, HRV was significantly decreased in patients with FAP at the early stage, and sympathetic activity was more decreased in patients at the advanced stage. These findings suggest that the decrease of the HRV is an indicator of this disease and the power spectral analysis of the HRV is beneficial in assessing the severity of the autonomic dysfunction.

An investigation into the distributive pattern, classification and functional role of the conical papillae on the posterodorsal surface of the cat tongue using SEM

In order to examine the relationship between their distributive patterns, classification and functional roles, three-dimensional structures in the microvascular network of the conical papillae (CoP) on the posterior third of the central dorsal surface of the cat tongue were observed by the corrosion cast method under a scanning electron microscope (SEM). CoP can be classified into two types: small conical papillae (SCoP) and large conical papillae (LCoP), according to their shape, size and distributive pattern. On the posterior third of the central dorsal surface of the tongue, SCoPs are arranged in the form of six-eight straight lines running regularly from the posterior third of the central zone towards the pharynx. LCoPs are also arranged in the form of a V, with the point directed posteriorly, in oblique lines running in an orderly fashion from both the antero-peripheral zones to the central zone. To summarize CoPs play an important role in the drinking of milk and water, after mixing the food with saliva, in the transport of the food mass towards the pharynx and in swallowing it.

Microvascular fin-like structure of the foliate papillae of the rabbit tongue using scanning electron microscopic specimens

Although many morphological studies have been undertaken on the lingual papillae of the rabbit tongue, relatively few have dealt with the microvascular structure and classification of the foliate papillae (FoP) by means of microvascular cast specimens (MVCS) and using scanning electron microscopy (SEM). For the present study, a three dimensional observation and classification was carried out by SEM. The morphological characteristics of the outer frame structure were observed by means of MVCS of FoP which were located on both posteroperipheral parts of the tongue. They showed a bead-like appearance and consisted of 14-18 transverse and slightly bent fin-like structures, running from the dorsal surface to both peripheral sides symmetrically. These are effectively increased on the surface areas and play the functional role of receiving the taste sense. FoPs can be classified into three types: type I (14 fins), type II (16 fins), type III (18 fins) according to the fin numbers.

Effect of denervation on lymphocytes and dendritic cells in the rat circumvallate and foliate papillae

The distribution of dendritic (Langerhans) cells and lymphocytes in rat circumvallate and foliate papillae was examined by immunohistochemistry and electron microscopy. Light microscopic immunohistochemistry using anti-OX62 antibody, which recognizes both gammadelta T lymphocytes and dendritic cells, showed that many OX62-immunoreactive cells had invaded into the trench wall epithelium from the connective tissue at 6 days after sectioning of the glossopharyngeal nerves. The presence of OX62-immunoreactive cells in the epithelium was observed up to 17 days after the denervation, by which time the taste buds had disappeared from the trench wall. The OX62-positive cells were again observed in the connective tissue at 24 and 40 days when taste buds regenerated. The local circulation of OX62-positive cells between the epithelium and connective tissue is suggested. Most of the OX62-positive-cells in the epithelium of circumvallate and foliate papillae were suggested to be gammadelta T cells, since they were round or spindle-shaped. Electron micrographs of OX62-positive cells also indicated that they were lymphocytes. Furthermore, they expressed CD3 but lacked CD4 and CD8 surface markers. A few dendritic cells, which reacted with anti-OX6 antibody, were observed in the circumvallate and foliate papillae in the control and denervated animals, and they were irregular in shape with long cytoplasmic processes. Electron micrographs taken at 6 days showed that the dendritic cells, which were characterized by the presence of Birbeck granules in the cytoplasm, were in contact with lymphocytes. The finding suggests that gammadelta T lymphocytes and dendritic cells in the rat circumvallate and foliate papillae interact with each other to respond to changes such as the presence or absence of taste buds in the epithelium.

Effects of tachykinins on rapidly adapting pulmonary stretch receptors and total lung resistance in anesthetized, artificially ventilated rabbits

In anesthetized, artificially ventilated rabbits not treated with thiorphan (2 mg/kg), a neutral endopeptidase (NEP) inhibitor, substance P (SP) and neurokinin A (NKA) in doses from 0.2 to 2.7 microg/kg produced dose-related increases in rapidly adapting pulmonary stretch receptor (RAR) activity without any significant changes in total lung resistance (RL), whereas neurokinin B (NKB) at the same concentrations did not significantly alter either RAR activity or RL. In comparison with the excitatory responses of RAR activity to SP and NKA, the magnitudes of increased receptor activity evoked SP were significantly larger than those after NKA administration. The rank order of tachykinins for RAR stimulus potency was SP > NKA > KB. Pretreatment with thiorphan potentiated the increases of RAR activity and RL induced by SP but had no effect on the RAR and RL responses to NKA and NKB. Subsequent administration of L 659, 877 (a selective NK2 receptor antagonist, 2. 3 and 7.6 microg/kg) that dose-dependently inhibited NKA-induced RAR stimulation did not significantly influence augmentation of the RAR and RL responses to SP. Administration of atropine (2 mg/kg, n = 6) in thiorphan-treated rabbits, which had no effect on NKA- and NKB-induced RAR stimuli, significantly attenuated the increases of RAR activity and RL induced by SP. These results suggest that tachykinin-induced RAR stimulation is mediated by the activation of NK2 receptors, probably involving participation of NK1 receptors. Furthermore, potentiation of the increases of RAR activity and RL produced by SP administration in the presence of thiorphan is partly mediated by facilitation of cholinergic neurotransmission.

Enhancement of cytotoxic activity of ascorbate by Acer nikoense Maxim. Extracts

Millimolar concentrations of ascorbic acid or sodium ascorbate induced cytotoxicity against human glioblastoma T98G cells. Addition of hot water and sodium hydroxide extracts of the bark of Acer nikoense Maxim. synergistically enhanced the cytotoxic activity of ascorbate. Human peripheral blood lymphocytes and polymorphonuclear cells were relatively resistant to ascorbate, the Acer nikoense Maxim. extract, or a combination of them. The extracts stimulated the degradation of ascorbates via ascorbyl radical production, in parallel with their ability to stimulate the cytotoxic activity of ascorbate. The results suggest the medicinal efficacy of the Acer nikoense Maxim. extracts.

Arachidonic acid inhibits myelin basic protein phosphorylation in cultured oligodendrocytes

Protein phosphorylation is a well-known mechanism by which extracellular molecules or factors transduce their signals into intracellular effects. In the context of myelin assembly, phosphorylation of major myelin proteins affects the electrostatic repulsion between adjacent proteins within myelin structure and therefore constitutes one of the mechanisms by which myelin stability is regulated. We report here that arachidonic acid (AA) decreases the phosphorylation of myelin basic protein (MBP) both in the absence and in the presence of phorbol esters in cultured rat oligodendrocytes (OLGs). The effect of AA on MBP phosphorylation is not mediated by cyclooxygenase products, though the possibility that leukotrienes or other epoxides may have a role cannot be excluded. AA did not act by inactivation of protein kinase C. Based on our findings from gadolinium and low K+ experiments, we conclude that inhibition of MBP phosphorylation is not dependent on AA-induced increases in OLG Ca(i), but rather on its depolarizing action. We have thus demonstrated that a brief exposure to AA, which either acts as a diffusible paracrine signal to OLGs or as a signal transducer, can trigger changes in protein phosphorylation in OLGs/myelin via ionic signaling events at the plasma membrane.

Cisplatin-induced apoptosis of immortalized mouse proximal tubule cells is mediated by interleukin-1 beta converting enzyme (ICE) family of proteases but inhibited by overexpression of Bcl-2

Cisplatin is known to induce serious renal damage including acute renal failure, the major site of renal injury appears to be localized to the third segment of the proximal tubule (S3). Apoptosis occurs during a variety of acute injuries to tubule cell. The purpose of this study was to determine whether cisplatin induces apoptosis of immortalized mouse S3 cells, and to define the intracellular pathways leading to cell death. S3 cells exposed to cisplatin exhibited biochemical, morphological, and flow cytometric changes characteristic of apoptosis associated with slight necrosis. Cisplatin-induced apoptosis could be inhibited by overexpression of crmA, a cowpox virus gene, of which the product is known to suppress activities of the interleukin-1 beta converting enzyme (ICE) family proteases. On the other hand, overexpression of bcl-2, an antiapoptotic oncogene, rendered S3 cells partially resistant to cisplatin. These results indicate that cisplatin-induced proximal tubule damage is associated with apoptosis, which is positively modulated by the ICE family of proteases and negatively by the product of bcl-2.

Angioarchitectural classification of the fungiform papillae on the dorsal surface of the bullfrog tongue

In this study, the three-dimensional anatomy of the microvascular structure of fungiform papillae (FuP) on the dorsal surface of the bullfrog tongue has been investigated using scanning electron microscopy (SEM), and angioarchitectural classification has been carried out by means of the capillary loop (L. s) and intra-bridge structure (I. b). FuP from 30 sound bullfrog tongues were used. The following research methods were applied: SEM observation on microvascular cast specimens (MVCS) of bullfrog tongue's FuP were injected with synthetic resin (Mercox). Observation of MVSC showed that the bullfrog tongue FuP consisted of an ascending branch (A. b), L. s, I. b and a descending branch (D. b). Based upon SEM observations of MVCS, FuP can be classified into four types: A, B, C, D types according to A. b, L. s, I. b and D. b. A-type (none I. b) formed from A. b, L. s, D. b only and with no I. b. B-type (one I. b) consisted of A. b, L. s, D. b and one I. b. C-type (two I. b) were composed of A. b, L. s, D. b and two I. b. D-type (three I. b) were composed of A. b, L. s, D. b and three I. b, A. b, L. s, I. b and D. b on each. A, B, C, D types were all same thickness.

Angioarchitectural structure of the fungiform papillae on the anterodorsal surface of the rat tongue

To ascertain whether the microvascular morphological differences of fungiform papillae (FuP) on the anterodorsal surface of the rat tongue are locationally and functionally related, this study aimed at examining and comparing, in greater detail, the comparative morphological characteristics of FuP. FuP were sporadically and consistently scattered among numerous filiform papillae (FiP) in three parts: the apical, central and in front of the intermolar eminence on the anterodorsal surface. We studied these by means of the microvascular cast specimen (MVCS) of FuP using scanning electron microscopy (SEM). The results obtained in this study showed that in all three parts on the anterodorsal region, the capillary bed of FuP presented as a netbasket-like and cylindrical figure with a central hole consisting of 4-5 horizontal rings of several ascending and descending roots. FuP in the central part on the anterodorsal region were relatively larger in size and more cylindrical in shape than those of both the other parts, and they play the leading part as sensory organs for the taste sense and were regarded as taste receptive organs.

Induction of apoptosis in human eosinophilic leukemic cell line (EOL-1)

Exposure of human eosinophilic leukemic EOL-1 cells to H2O2, ascorbic acid derivatives, actinomycin D, low-molecular-weight polyphenols, UV irradiation, or hyperthermia resulted in nuclear fragmentation, but failed to induce internucleosomal DNA cleavage. The findings suggest that internucleosomal DNA fragmentation is not a universal biochemical hallmark of apoptosis. Removal of Ca2+ ions from the culture medium significantly reduced the cytotoxic activity of sodium ascorbate, but not that of H2O2. H2O2 significantly elevated the intracellular Ca2+ concentration, with or without Ca2+ in the culture medium. This suggests that sodium ascorbate and H2O2 initiate cell death by different mechanisms. Induction of apoptosis in in vitro systems might be useful in studying the pathogenesis of allergy or asthma.

Response of respiratory epithelium of BN and F344 rats to formaldehyde inhalation

BN rats are well-known for their high capacity for IgE production and hyperresponsiveness to exposure to allergens or other chemicals. We examined the histological changes in the nasal cavity, trachea and lungs of BN and F344 rats after the inhalation of aerosol formaldehyde (HCHO), which exerts direct toxic effects on the respiratory system. The incidence of clinical signs such as sneezing and abnormal respiration in HCHO-treated F344 rats was higher than that in HCHO-treated BN rats. The mean body weight of HCHO-treated F344 rats apparently decreased in comparison with control F344 rats, but that of HCHO-treated BN rats was not significantly different from that of control BN rats. Changes such as squamous metaplasia, stratification, degeneration and desquamation were observed by light microscopy in nasal, tracheal and bronchial mucosa in the lungs of the HCHO-treated F344 rats. In the HCHO-treated BN rats, similar but milder lesions were restricted to the nasal mucosa. Scanning electron microscopic observation supported these light microscopic observations. These results suggest that BN rats have lower sensitivity to HCHO inhalation than F344 rats.

Apoptosis of murine hepatocytes induced by high doses of galactosamine

Apoptosis induced by high doses of Galactosamine (GalN) was investigated in mice hepatocytes in vivo. In mice intraperitoneally (i.p.) treated with GalN 3 g/kg, the terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL)-positive cells were first observed at 6 hr postadministration (PA). Both acidophilic bodies in hematoxylin and eosin (HE)-stained sections and TUNEL-positive cells were markedly found at 24 hr PA. At 48 hr PA, cellular degeneration and necrosis of hepatocytes were prominently observed, and TUNEL-positive cells were scarcely found. In the mice ip treated with GalN 1.5 g/kg, the lesion was milder than that in those treated with GalN 3 g/kg. Acidophilic bodies and TUNEL-positive cells were scarcely found at 24 hr PA, whereas they were markedly seen at 48 hr PA. In addition, a ladder-like DNA fragmentation pattern by agarose gel electrophoresis was observed most remarkably at 24 hr PA with GalN 3 g/kg and at 48 hr PA with GalN 1.5 g/kg, and less distinctly at 48 hr PA with GalN 3 g/kg. On the other hand, sGOT and sGPT activities increased prominently at 48 hr PA with GalN 3 g/kg. These results suggest that the cell death induced by high dose of GalN may be caused by apoptosis, and subsequently by necrosis in vivo.

Functional role of V form distribution seen in microvascular cast specimens of the filiform and fungiform papillae on the posterior central dorsal surface of the cat tongue

The relationship between the functional role and three-dimensional structures of the microvascular network of the filiform papillae (FiP) and fungiform papillae (FuP) on the posterior central surface of the cat tongue were observed by the corrosion cast method under a scanning electron microscope (SEM). FiP can be classified into five types; types I-V (Ojima and Lowe 1995), and FuP, found to be distributed sporadically among FiP (I-V), into four types; types I-IV (Ojima et al. 1996 b) according to the shape and size of the main process (MP) and the number of the accessory processes (AP). Each of the types I-V of FiP were arranged in the form of a V as oblique lines running in an orderly and geometrical fashion from the posterior central zone to the anterior peripheral zone in both directions. Each of the types I-IV of FuP were scattered throughout the line of FiPs arranged in the form of a V, the point of which is directed towards the pharynx. FiPs play an important role in the drinking of milk and water, holding, masticating and swallowing the food and, after mixing the food with saliva, in the transporting of the food mass towards the pharynx. The MP of FuPs is considered to be a modified form of the MP of FiP of the cat tongue function (Ojima et al. 1996 c) as part of a sense organ for taste.

Angioarchitectural structure of the fungiform papillae on rabbit tongue anterodorsal surface

The relationships between the functional and morphological characteristics and the positional difference of the microvascular cast specimen (MVCS) of the fungiform papillae (FuP) on the antero-dorsal surface of the rabbit tongue were examined and compared using a scanning electron microscope (SEM). The sporadic FuPs scattered among the numerous small filiform papillae (SfP) were found to be distributed irregularly over the antero-dorsal surface. FuPs consisted of the ascending and descending capillary loops, forming margins of the central opening at the top of FuP. They resembled flower-like configurations (carnations), the petals of which ranged from eight to twelve, and they were larger in width and more complex in shape than SfPs with morphological differences. FuPs can be classified into three types: type I (consisting of eight petals), type II (ten petals), type III (twelve petals) according to the shape of FuP, and to the petal number of the flower-like aspect on the eight points of MVCS of FuPs observed by SEM. These results suggest that the petals of the ascending and descending capillary loops of FuP expanded the flower-like figure, increased in the surface areas and effectively play a role in receiving the sense of taste.

Frequency-multiplex Fourier-transform profilometry: a single-shot three-dimensional shape measurement of objects with large height discontinuities and/or surface isolations

The performance of Fourier-transform profilometry is enhanced by a new technique that is based on spatial frequency multiplexing combined with the Gushov-Solodkin phase unwrapping algorithm. The technique permits the three-dimensional shape measurement of objects that have discontinuous height steps and/or spatially isolated surfaces, which has not been possible by conventional Fourier-transform profilometry. An important feature of the technique is that it requires only a single fringe pattern; the single-shot recording makes possible the instantaneous three-dimensional shape measurement of discontinuous objects in fast motion. Experimental results are presented that demonstrate the validity of the principle.

Galactosamine-induced apoptosis in the primary mouse hepatocyte cultures

Galactosamine (GalN)-induced apoptosis was investigated in cultured hepatocytes from mice. The percentage of fragmented DNA measured by the ELISA method increased in a concentration-dependent manner from the very early stage, i.e. 0.5 hrs, after GalN-exposure. In addition, a ladder-like fragmentation pattern by agarose gel electrophoresis appeared first at 3 hr-exposure to 20 mM GalN, at 6 hr-exposure to 10 mM GalN and at 12 hr-exposure to 5 mM GalN, respectively. On the other hand, cytotoxicity indicated by leakage of lactate dehydrogenase from cultured hepatocytes to culture medium was first detected at 24 hrs after GalN-treatment. Morphologically, formation of blebs and apoptotic bodies was observed from 12 hr-exposure to 20 mM GalN and from 24 hr-exposure to 10 mM GalN, respectively. Thus GalN could induce apoptosis in primary hepatocyte cultures from mice.

Plasma endothelin-1 level in patients with renovascular hypertension - does the kidney with stenosis of the renal artery upregulate production of endthelin-1?

PROBLEM

To examine the value of plasma endothelin-1 (ET-1), we measured the level of plasma ET-1 activity of peripheral venous blood and selective renal venous blood in renovascular hypertension patients, and compared that activity with corresponding renin activity and split renal function.

METHODS

ET-1 level, renin activity in selective renal venous blood and peripheral venous blood, and 99mTc-dimercaptosuccinic acid renal uptake as a split renal function test were measured in 11 patients (mean 42.1 years old) with renovascular hypertension (RVH) and 6 patients with both renal cell cancer (RCC) and essential hypertension.

RESULTS

1. In patients with RVH, resting peripheral venous plasma ET-1 ranged from 0.6 to 8.1 (mean 4.07) pg/ml and was higher than the normal level (p <0.01). However, the renal vein ET-1 ratio was nor correlated with the renal vein renin ratio. 2. In patients with RCC, resting peripheral venous plasma ET-1 was not different from the normal level. There was no step-up of plasma ET-1, or renin among renal veins, or the proximal and distal parts of the interior vena cava. 3. Both renal vein renin ratio and renal vein ET-1 ratios were inversely correlated with t99mTC-dimercaptosuccinic acid renal uptake as a split renal function examination in patients with RVH. 4. The peripheral plasma ET-1 level was correlated with the degree of stenosis of the renal artery in patients with RVH of a unilateral lesion, but not bilateral lesions.

CONCLUSION

These results suggest that ET-1 may take part in the hypertensive mechanisms of RVH in addition to the renin-angiotensin system, but its significance in RVH still remains to be examined.

Tissue and subcellular distributions, and characterization of rat brain protein phosphatase 2A containing a 72-kDa delta/B" subunit

A 74-kDa delta/B" subunit was isolated by heparin-Sepharose column chromatography from human erythrocyte protein phosphatase 2A (PP2A) consisting of a 34-kDa catalytic subunit (alpha/C) and 63- and 74-kDa regulatory subunits (beta/A and delta/B") in a ratio of 1:1:1. The purified delta/B" was used as an immunogen in mice, to prepare specific antisera against delta/B". Immunoblot analyses with the antisera detected an immunoreactive 72-kDa protein in the cytosol from various rat tissues including erythrocytes, brain, lung, testis, adrenal gland, heart, spleen, kidney, and liver. The 72-kDa protein was highly abundant in brain and was distributed evenly in cerebral cortex, cerebellum, and brain stem. The 72-kDa protein was also detected in mitochondria and microsome fractions. An immunoreactive 68-kDa protein was detected mainly in nuclear and microsome fractions. The 72-kDa protein from rat brain cytosol copurified with phosphorylated H2B histone phosphatase activity during successive chromatographies on DEAE-Toyopearl, AH-Sepharose, Sephadex G-150, H1 histone-Toyopearl, TSK DEAE-5PW, protamine-Toyopearl, and TSK G3000SW columns. The purified enzyme migrated as a single protein band on nondenaturing PAGE and as three protein bands of 34, 63, and 72 kDa in a ratio of 1:1:1 on SDS-PAGE. The molecular weight of the enzyme was estimated to be 170,000 from the s20,W value of 7.2 +/- 0.3 S and the Stokes radius of 5.5 +/- 0.1 nm. The rat brain enzyme was classified as PP2A, based on the following properties; (1) an IC50 for okadaic acid of 10(-9) M; (2) its preferential dephosphorylation of the a subunit of phosphorylase kinase; (3) its insensitivity to protein inhibitor 2; and (4) its heterotrimeric subunit structure. The Km value and the molecular activity of the enzyme for phosphorylated H2B histone were 72.3 +/- 0.3 microM and 192 +/- 2 mol Pi released/min/mol enzyme, respectively, and were comparable to those of human erythrocyte PP2A (alpha1 beta1 delta1/ CAB"). The 72-kDa subunit in the purified rat brain PP2A was phosphorylated in vitro by cAMP-dependent protein kinase.

Glycophorin-induced differentiation of human myelogenous leukemic cell lines

Human myelogenous leukemic cell lines, U-937, ML-1, and THP-1, were induced to differentiate into maturing macrophage-like cells upon treatment with any glycophorins from either human, monkey or cow erythrocyte membrane. The differentiated cells expressed lower growth potential, and higher nitroblue tetrazolium-reducing activity, Fc-receptor, phagocytic activity and non-specific esterase activity. The differentiation-inducing activities of the glycophorins were significantly reduced after neuraminidase treatment. On the other hand, sialic acid and colominic acid (a polymer of sialic acid) were inactive. These results suggest that some conformational requirement involving the linkage of sialic acid residues in the glycoproteins is necessary for the observed differentiation-inducing activity.

[A case of juvenile Huntington's disease presenting dystonia and confirmed by DNA analysis]

We reported a 13-year-old boy with juvenile Huntington disease diagnosed by DNA analysis. Symptoms started with dysarthria at 6 years of age, which was followed by progressive dysgraphia and gait disturbance due to dystonia from 7 years, and by epileptic seizures from 12 years. Magnetic resonance imaging revealed atrophy of the bilateral caudate nuclei and T2- and proton-weighted high intensity area in both putamina. The CAG (cytosine-adenine-guanine) trinucleotide repeat on chromosome 4 p16 was markedly expanded to 81. For a child with dystonia with mental deterioration, juvenile Huntington disease should be considered in the differential diagnosis.

Staurosporine-induced apoptosis of immortalized mouse proximal tubule cells is modulated by bcl-2 expression level

Mouse terminal proximal tubule (S3)cells treated with staurosporine (STS) underwent morphological and biochemical changes characteristic of apoptosis. Treatment of S3 cells with STS, H-7, PMA, herbimycin A or genistein caused DNA fragmentation. STS inhibited the activity of protein kinase C but not of cdc-2 kinase in S3 cells. No change in cell cycle distribution was observed in S3 cells treated with STS. However, treatment of S3 cells with STS resulted in a decrease in the level of bcl-2 mRNA expression in the cells. Overexpression of bcl-2 inhibited the degree of STS-induced apoptosis of S3 cells. In conclusion, STS induces apoptosis of mouse S3 cells via inhibition of various protein kinases including protein kinase C, and the apoptosis is modulated by the bcl-2 expression level.

Methionine oxidation and apoptosis induction by ascorbate, gallate and hydrogen peroxide

Addition of either ascorbate, gallate, caffeate or hydrogen peroxide to the culture medium stimulated the oxidation of free methionine to methionine sulfoxide, regardless of the presence or absence of the cells. In methionine-free medium, growth of human myelogenous leukemic cell lines was nearly stopped by G1 arrest, without induction of internucleosomal DNA cleavage. Methionine sulfoxide, a major oxidation product of methionine, was neither growth-promoting nor cytotoxic. On the other hand, methional, a deamination and decarboxylation product of methionine, was highly cytotoxic. The present study suggests that the apoptosis induction by these antioxidants and oxidant cannot simply be explained by methionine oxidation or depletion.

Effect of methionine depletion on growth and apoptosis in various tumor cell lines

Sodium ascorbate, sodium 5,6-benzylidene-L-ascorbate (SBA), gallic acid and caffeic acid induced apoptotic cell death in human myelogenous leukemic cell lines, and stimulated oxidation of methionine into methionine sulfoxide in the culture medium. When various tumor cell lines were cultured in methionine-free medium, their growth was nearly terminated at G1 phase of the cell cycle, producing much smaller number of apoptotic cells. Addition of methionine sulfoxide to the methionine-free medium did not stimulate the apoptosis induction. These data suggest that induction of apoptosis by ascorbates, gallate or by caffeate cannot be simply explained by methionine oxidation.