Nitrite-dependent nitric oxide production pathway: implications for involvement of active nitrogen species in photoinhibition in vivo

Air pollution studies have shown that nitric oxide (NO), a gaseous free radical, is a potent photosynthetic inhibitor that reduces CO2 uptake activity in leaves. It is now recognized that NO is not only an air pollutant but also an endogenously produced metabolite, which may play a role in regulating plant cell functions. Although many studies have suggested the presence of mammalian-type NO synthase (NOS) in plants, the source of NO is still not clear. There has been a number of studies indicating that plant cells possess a nitrite-dependent NO production pathway which can be distinguished from the NOS-mediated reaction. Nitrate reductase (NR) has been recently found to be capable of producing NO through one-electron reduction of nitrite using NAD(P)H as an electron donor. This review focuses on current understanding of the mechanism for the nitrite-dependent NO production in plants. Impacts of NO produced by NR on photosynthesis are discussed in association with photo-oxidative stress in leaves.

Effect of electromagnetic field exposure on chemically induced differentiation of friend erythroleukemia cells

Whether exposure of humans to extremely low frequency electromagnetic fields (ELF-EMF) can cause cancer is controversial and therefore needs further research. We used a Friend erythroleukemia cell line that can be chemically induced to differentiate to determine whether ELF-EMF could alter proliferation and differentiation in these cells in a manner similar to that of a chemical tumor promoter. Exposure of this cell line to 60 Hz ELF-EMF resulted in a dose dependent inhibition of differentiation, with maximal inhibition peaking at 40% and 40 mG (4 microT). ELF-EMF at 10 mG (1.0 microT) and 25 mG (2.5 microT) inhibited differentiation at 0 and 20%, respectively. ELF-EMF at 1.0 (100) and 10.0 G (1,000 microT) stimulated cell proliferation 50% above the sham-treated cells. The activity of telomerase, a marker of undifferentiated cells, decreased 100[times] when the cells were induced to differentiate under sham conditions, but when the cells were exposed to 0.5 G (50 microT) there was only a 10[times] decrease. In summary, ELF-EMF can partially block the differentiation of Friend erythroleukemia cells, and this results in a larger population of cells remaining in the undifferentiated, proliferative state, which is similar to the published results of Friend erythroleukemia cells treated with chemical-tumor promoters.

Type I and type II T cell profiles in chronic myelogenous leukemia

T cell immunity is considered to play an important role in the control of cell growth in chronic myelogenous leukemia (CML) although information regarding the characteristics of T lymphocytes in CML patients is limited. Using flow cytometric analysis of intracellular cytokine expression at the single-cell level, we analyzed helper T and cytotoxic T subsets in 8 CML patients. The percentage of interferon-gamma (IFN-gamma) single-positive CD4 cells (Th1) and that of interleukin-4 (IL-4) single-positive CD4 cells (Th2) was markedly decreased in pretreated CML patients compared to normal controls. In addition, the percentage of IFN-gamma/IL-4 double-positive CD4 cells (Th0) was also reduced. Consequently, the percentage of IFN-gamma/IL-4 double-negative CD4 cells was markedly increased. Similarly, a reduction in IFN-gamma single-positive CD8 cells (Tc1) and IFN-gamma/IL-4 double-positive CD8 cells (Tc0) and an increase in IFN-gamma/IL-4 double-negative CD8 cells were observed in pretreated CML patients. Imbalance of these parameters was markedly improved following cytoreduction therapy. Our findings directly indicate anergic states in CML patients. Determination of the factors that affect Th and Tc profiles may lead to further understanding of immunological states and the development of effective immunotherapy.

Octreotide treatment suppresses malignant somatotrophic pituitary tumor cell growth in rats

We have recently established an in vitro cell line (metastatic mGH3) derived from lymph node metastases of the rat pituitary somatotroph. Here we examined the in vivo effects of octreotide, a somatostatin analog, against malignant pituitary tumors. Wistar-Furth rats (n=8) were inoculated subcutaneously with mGH3 cells while control rats received injections of equal volumes of the vehicle only. Four rats were treated with octreotide three times daily while another group of four rats were treated with saline only. After 6 weeks of treatment, histopathological and immunohistological analyses were performed. The tumor weights of rats treated with octreotide were significantly lighter than those of untreated rats. All rats implanted mGH3, but not administered treatment, developed inguinal lymph node metastases, whereas none of those implanted mGH3 and treated with octreotide developed such metastases. The proportion of PCNA-stained tumor cells was higher in tumors of untreated rats than in those of octreotide-treated rats. However, the proportion of apoptotic cells in the tumor was not different between treated and untreated rats. Our results suggest that octreotide might be potentially effective for invasive and malignant human pituitary tumors by regulating the tumor cell cycle.

[A resected case of lung cancer with an extrapericardial single trunk formed by the left pulmonary veins]

We successfully performed left lower lobectomy in a lung cancer patient with anatomical variation in which left superior and inferior pulmonary veins were connected to the left atrium after foaming an extrapericardial single trunk. When indicating lobectomy, confirming the presence of such anatomical variation is clinically significant to prevent the development of pulmonary edema in the residual lung due to improper division of the single trunk as well as preventing subsequent possibly essential completion pneumonectomy.

Flavonoid-induced expression of a symbiosis-related gene in the cyanobacterium Nostoc punctiforme

The flavonoid naringin was found to induce the expression of hrmA, a gene with a symbiotic phenotype in the cyanobacterium Nostoc punctiforme. A comparative analysis of several flavonoids revealed the 7-O-neohesperidoside, 4'-OH, and C-2-C-3 double bond in naringin as structural determinants of its hrmA-inducing activity.

The somatosensory evoked magnetic fields

Averaged magnetoencephalography (MEG) following somatosensory stimulation, somatosensory evoked magnetic field(s) (SEF), in humans are reviewed. The equivalent current dipole(s) (ECD) of the primary and the following middle-latency components of SEF following electrical stimulation within 80-100 ms are estimated in area 3b of the primary somatosensory cortex (SI), the posterior bank of the central sulcus, in the hemisphere contralateral to the stimulated site. Their sites are generally compatible with the homunculus which was reported by Penfield using direct cortical stimulation during surgery. SEF to passive finger movement is generated in area 3a or 2 of SI, unlike with electrical stimulation. Long-latency components with peaks of approximately 80-120 ms are recorded in the bilateral hemispheres and their ECD are estimated in the secondary somatosensory cortex (SII) in the bilateral hemispheres. We also summarized (1) the gating effects on SEF by interference tactile stimulation or movement applied to the stimulus site, (2) clinical applications of SEF in the fields of neurosurgery and neurology and (3) cortical plasticity (reorganization) of the SI. SEF specific to painful stimulation is also recorded following painful stimulation by CO(2) laser beam. Pain-specific components are recorded over 150 ms after the stimulus and their ECD are estimated in the bilateral SII and the limbic system. We introduced a newly-developed multi (12)-channel gradiometer system with the smallest and highest quality superconducting quantum interference device (micro-SQUID) available to non-invasively detect the magnetic fields of a human peripheral nerve. Clear nerve action fields (NAFs) were consistently recorded from all subjects.

Type I and type II T-cell profiles in aplastic anemia and refractory anemia

Immune-mediated suppression of hematopoiesis has been considered the most important mechanism in the development of idiopathic aplastic anemia (AA) and some types of myelodysplastic syndrome (MDS). Using flow cytometric analysis of intracellular cytokine expression at the single-cell level, we analyzed helper-T (Th) and cytotoxic-T (Tc) subsets in patients with AA and MDS of refractory anemia (RA) subtype. The results showed marked increases in the Th1/Th2 ratio and Tc1/Tc2 ratio in both AA and MDS/RA. Overproduction of cytokines inhibitory to hematopoiesis reported so far might be a reflection of imbalanced development of Th and Tc. Determination of the factors that affect Th and Tc profiles may lead to further understanding of immunological states and the development of effective immunotherapy in AA as well as some types of MDS.

Bystander effect in herpes simplex virus-thymidine kinase/ganciclovir cancer gene therapy: role of gap-junctional intercellular communication

Antitumor suicide gene therapy is one of the emerging strategies against cancer. It consists of the introduction into cancer cells of a gene capable of converting a nontoxic prodrug into a cytotoxic drug. Because this therapeutic gene cannot be easily introduced into the whole cell population of a tumor, the successful eradication of tumors depends on a phenomenon called the "bystander effect," by which the introduced gene can affect even cells in which it is not itself present. From a therapeutic point of view, it may be crucial to enhance this phenomenon through various means to achieve tumor eradication. One such suicide gene, the thymidine kinase gene from the herpes simplex virus, in combination with the prodrug ganciclovir, has been extensively and successfully used in some animal models exhibiting a strong bystander effect. Among the mechanisms involved in this phenomenon, gap junctional intercellular communication (GJIC) is directly involved in the transfer of the toxic metabolites of ganciclovir, which pass directly from herpes simplex virus thymidine kinase-expressing cells to surrounding cells that do not express it. Because GJIC appears to be a mediator of the bystander effect both in vitro and in vivo, here we review possible molecular strategies for enhancing the extent of tumor cell death by increasing the intratumoral GJIC capacity.

Magnetic response of human extrastriate cortex in the detection of coherent and incoherent motion

Although direction selectivity is a cardinal property of neurons in the visual motion detection system, movement of numerous elements without global direction (incoherent motion) has been shown to activate human and monkey visual systems, as does coherent motion which has global direction. We used magnetoencephalography to investigate the neural process underlying responses to these types of motions in the human extrastriate cortex. Both motions were created using a random dot kinematogram and four speeds (0, 0.6, 9.6 and 25 degrees /s). The visual stimuli were composed of two successive motions at different speeds; a coherent motion at a certain speed that changed to incoherent motion at another speed or vice versa. Magnetic responses to the change in motion consisted of a few components, the first of which was always largest. The peak latency of the first component was inversely related to the speed of the preceding motion, but for both motions it was not affected by the speed of the subsequent motion. For each subject, the estimated origin of the first component was always in the extrastriate cortex, and this changed with the speed of the preceding motion. For both motions, the location for the slower preceding motion was lateral to that for the faster preceding motion. Although the latency changes of the two motions differed, their overall response properties were markedly similar. These findings show that the speed of incoherent motion is represented in the human extrastriate cortex neurons to the same degree as coherent motion. We consider that the human visual system has a distinct neural mechanism to perceive random dots' motion even though they do not move in a specific direction as a whole.

Effect of non-weight-bearing body fat on bone mineral density before and after menopause

OBJECTIVE

To investigate the difference in the effect of non-weight-bearing body fat mass on bone mineral density between premenopausal and postmenopausal women.

METHODS

We studied 252 regularly menstruating premenopausal women and 213 postmenopausal women with right side dominance. Age, years since menopause (in postmenopausal women), height, weight, and body mass index were recorded. Bone mineral density of non-weight-bearing sites (ie, arms), weight-bearing sites (ie, lumbar spine including L2-4 and legs), and body fat mass were measured by whole-body scanning with dual-energy x-ray absorptiometry. Body fat mass was also measured by dual energy x-ray absorptiometry.

RESULTS

Body fat mass did not differ between groups. In postmenopausal women, body fat mass correlated positively with bone mineral density of the left leg (r =. 41, P <.001), right leg (r =.36, P <.001), left arm (r =.31, P <. 001), and lumbar spine (r =.27, P <.001). The correlation between body fat mass and bone mineral density of the left arm remained significant after adjusting for age, years since menopause, and height. In premenopausal women, body fat mass correlated positively with bone mineral density of left leg (r =.37, P <.001) and right leg (r = 0.31, P <.001), but correlated weakly with bilateral arms (r < or =.19) and lumbar spine bone mineral density (r = 0.13, P <.05).

CONCLUSION

The effect of non-weight-bearing body fat on bone mineral density was greater in postmenopausal than premenopausal women.

CC to TT mutation in the mitochondrial DNA of normal skin: relationship to ultraviolet light exposure

We have previously reported that ultraviolet (UV)-specific (CC to TT) mutations in p53 gene can be detected in normal skin. This, however, cannot be used as a cumulative marker of UV exposure, since cells with the p53 mutation acquire a clonal growth advantage. Moreover, a large skin biopsy is necessary for each assay. In order to circumvent these problems, we have measured mitochondrial (Mt) DNA mutations; there are more than 1000 copies of the Mt genome per cell, and Mt genes are not directly involved in cell growth. We have established a sensitive allele-specific polymerase chain reaction (AS-PCR) assay capable of detecting one CC to TT mutation in Mt DNA among 10(7) wild-type genes using a mismatch allele-specific primer. With this assay, we found no mutation-positive samples from internal non-exposed tissue (stomach, colon, and blood) (0/50). In contrast, 17 out of 111 skin samples were positive: the mutation frequency in positive samples was around 10(7)-10(-6) (10-100 copies of mutant in 10(8) wild-type Mt DNA). In normal skin tissue, the prevalence of positive samples was higher in those from exposed sites (13/51) than in those from less-exposed sites (1/26) (p<0.05). However, a quantitative correlation between sunlight exposure and the accumulation of mutations was not found. We conclude that the UV exposure-associated CC to TT mutation in Mt DNA can be detected in normal skin, but that further studies are required to develop this as a quantitative marker for UV exposure.

Classical cadherins in urological cancers

Decreased E-cadherin expression assessed by immunohistochemistry correlates with poor survival of bladder and prostate cancer patients. The clinical usefulness of this parameter should therefore be evaluated in a large scale prospective study. In proximal kidney tubule and in its derived tumours cadherin-6 seems to take over E-cadherin function. Impaired E-cadherin function leads to increased invasive capacity of the cells. It has been shown that defective function can result from several mechanisms: mutation of the gene, alteration of transcription, post translational modifications or changes in the interaction of E-cadherin with cytoskeleton anchoring proteins: the catenins. A major mechanism leading to decreased E-cadherin expression in tumours lies in decreased transcription of the gene. Hence, a better understanding of the regulation of E-cadherin transcription might open avenues for therapy by restoring a normal expression.

The significance of serum homocysteine levels in diabetic patients on haemodialysis

BACKGROUND

Atherosclerotic diseases are the major cause of mortality and morbidity in patients on haemodialysis (HD). Furthermore, the prognosis of diabetic patients on HD is especially poor due to atherosclerotic complications. Because homocysteine (Hcy), a sulfur-containing amino acid, is emerging as an important risk factor for atherosclerosis in patients with end-stage renal disease, we examined the significance of serum Hcy levels in diabetic patients on HD.

METHODS

We measured total serum Hcy levels (tHcy) in 31 patients with diabetes mellitus on HD (DM group) and 37 non-diabetic patients on HD (N group), adjusting for age and HD duration. Linear regression analysis was used to assess the correlation of multiple variables to tHcy.

RESULTS

The proportion of atherosclerotic disease in the DM group was significantly higher than in the N group. However, serum tHcy, serum creatinine and per cent creatinine generation rate in the DM group were significantly lower than in the N group. In the DM group, serum tHcy was positively correlated with creatinine, albumin and per cent creatinine generation rate, respectively. This was not the case in the N group.

CONCLUSIONS

The demethylation pathway in methionine metabolism in the liver, which is linked directly to the creatinine generation system, may be disturbed in diabetic patients on HD. This may be the reason why serum tHcy and creatinine in diabetic patients on HD are lower than in non-diabetic patients on HD. Therefore, it is necessary to consider the possibility of an altered relation between serum tHcy and vessel disease when evaluating the atherogenic risk in diabetic patients on HD.

Pain-Related somatosensory evoked potentials

The authors reviewed basic and clinical reports of pain-related somatosensory evoked potentials (SSEP) after high-intensity electrical stimulation [pain SSEP(E)] and painful laser stimulation [pain SSEP(L)]. The conduction velocity of peripheral nerves for both pain SSEP(E) and pain SSEP(L) is approximately 10 to 15 m/second, in a range of Adelta fibers. The generator sources are considered to be the secondary somatosensory cortex and insula, and the limbic system, including the cingulate cortex, amygdala, or hippocampus of the bilateral hemispheres. The latencies and amplitudes are clearly affected by vigilance, attention-distraction, and various kinds of stimulation applied simultaneously with pain. Abnormalities of pain SSEP(L) reflect an impairment of pain-temperature sensation, probably relating to dysfunction of A5 fibers of the peripheral nerve and spinothalamic tract. In contrast, conventional SSEP after nonpainful electrical stimulation reflects an impairment of tactile, vibratory, and deep sensation, probably relating to dysfunction of Aalpha or Abeta fibers of the peripheral nerve and dorsal column. Therefore, combining the study of pain SSEP(L) and conventional SSEP is useful to detect physiologic abnormalities, and sometimes subclinical abnormalities, of patients with peripheral and central nervous system lesions.

A role for heterologous gap junctions between melanoma and endothelial cells in metastasis

F10 and BL6 sublines of B16 mouse melanoma cells are metastatic after intravenous injection, but only BL6 cells are metastatic after subcutaneous injection. We found that connexin (Cx) 26 is upregulated in BL6 cells. To examine gap junction formation, we devised a coculture system, in which an opened vein segment was placed at the bottom of a culture dish and then dye-labeled melanoma cells were seeded onto it. Immunohistochemistry indicated that the vein segment preserved the integrity of the endothelial monolayer. In this system, BL6 cells could transfer dye into endothelial cells but F10 cells could not. Transfection with wild-type Cx26 rendered F10 cells competent for coupling with endothelial cells and as spontaneously metastatic as BL6 cells. Conversely, transfection with a dominant-negative form of Cx26 rendered BL6 cells deficient in coupling and less metastatic. In human melanoma lesions, the level of Cx26 expression was low in melanoma cells residing in the basal layer, but significantly upregulated in melanoma cells invading the dermis. The results suggested that Cx26 plays a role in intravasation and extravasation of tumor cells through heterologous gap junction formation with endothelial cells.

The effects of physical exercise on body fat distribution and bone mineral density in postmenopausal women

OBJECTIVE

The present cross-sectional study investigated the effects of physical exercise on body fat distribution and bone mineral density (BMD).

METHODS

Subjects were 57 postmenopausal women (mean age, 60.5+/-6.4 years) who had exercised regularly for at least 2 years. Controls were 130 age-matched sedentary women. Age, years since menopause (YSM), height, weight, and body mass index (BMI, wt./ht.(2)) were recorded. Total fat mass, percentage of body fat, trunk fat mass, leg fat mass, the ratio of trunk fat mass to leg fat mass (trunk-leg fat ratio), total body lean mass, percentage of body lean, and lumbar spine BMD (L2-L4) were measured by dual-energy X-ray absorptiometry.

RESULTS

Baseline characteristics and leg fat mass did not differ between the two groups. Total fat mass, percentage of body fat, trunk fat mass, and trunk-leg fat ratio were lower (P<0.05, P<0.01, P<0.01 and P<0.001, respectively), while total body lean mass, percentage of body lean mass, and lumbar spine BMD were higher in exercising women (P<0.05, P<0.05 and P<0.01, respectively). Performing physical exercise was inversely correlated with trunk-leg fat ratio (standardized regression coefficient=-0.178, P<0.01), but positively correlated with BMD (0. 203, P<0.01) irrespective of age, height, YSM, and total fat mass.

CONCLUSION

Physical exercise has beneficial effects on body fat distribution and BMD in postmenopausal women. Reduction of upper body fat distribution with physical exercise may be more attributable to the decrease in trunk fat mass.

Human hemangiosarcomas have a common polymorphism but no mutations in the connexin37 gene

Gap junctional intercellular communication is often impaired in cancers, and the genes which encode the connexin gap junction proteins are considered to be tumor-suppressor genes. In this study, we analyzed the presence of mutations in the connexin 37 (Cx37) gene in 22 human hepatic angiosarcomas, 6 and 4 of which were associated with exposure to vinyl chloride and Thorotrast, respectively. The other 12 samples were from patients with no history of exposure to these 2 agents. In 9 samples, a proline (ACC) to serine (ACT) amino acid change in codon 319 was detected. However, DNA from non-tumorigenic tissue of the same patients also showed this amino acid change, suggesting that this is a polymorphism rather than a mutation. Subsequent analysis of 84 DNA samples from normal donors revealed the frequencies of Pro/Pro, Pro/Ser and Ser/Ser alleles to be 65.5%, 23.8% and 10.7%, respectively, while among the group of angiosarcoma patients the corresponding figures were 59.1%, 31.8% and 9. 1%, respectively. Thus, there was no correlation between the polymorphism at codon 319 and hepatic angiosarcoma occurrence. However, among the 6 cases of vinyl chloride-associated angiosarcoma, the percentages of the polymorphic alleles were 33.3%, 66.7% and 0%, respectively. While the number of samples was too small to allow us to conclude that the Ser319 allele in Cx37 predisposes to this rare type of human cancer, it may be noted that codon 319 is located at the cytoplasmic tail of Cx37, where most regulatory sequences reside, and that it could be a site of phosphorylation for some protein kinases, which may in turn affect the function of Cx37, including intercellular communication.

Development of a highly specific recombinant Toxocara canis second-stage larva excretory-secretory antigen for immunodiagnosis of human toxocariasis

The specificity of the recombinant Toxocara canis antigen developed for the immunodiagnosis of human toxocariasis was compared with that of the excretory-secretory antigen from T. canis second-stage larvae (TES) by enzyme-linked immunosorbent assay. A total of 153 human serum samples from patients infected with 20 different helminths, including 11 cases of toxocariasis, were examined. No false-negative reactions were observed for the toxocariasis cases. When the TES was used at concentrations of 0.5 and 0.125 microg/ml, cross-reactions were observed in 79 (55.6%) and 61 (43.0%) of 142 cases, respectively. In contrast, when the recombinant antigen was tested at a concentration of 0.5 microg/ml, cross-reactions were observed in 19 (13.4%) of 142 cases. At a concentration of 0.125 microg/ml, however, the cross-reaction rate decreased sharply to only 2.1%, corresponding to 3 of 142 cases. The cross-reactions occurred with one case each of gnathostomiasis, paragonimiasis with Paragonimus miyazakii, and spirometriasis, in which high antibody titers were detected. In addition, the recombinant antigen showed negative reactions with serum samples from patients infected with Ascaris and hookworms, which are the most common parasites in the world. These findings are also supported by experiments with animals infected with Ascaris and hookworm. From these results, the recombinant antigen is highly specific for toxocariasis and may provide more reliable diagnostic results than other methods.

Evaluation of insulin response in glucose tolerance test in a patient with Werner's syndrome: a 16-year follow-up study

To clarify the effect of Werner's syndrome (WS) on beta-islet cell function, the oral glucose tolerance test (OGTT) was repeatedly performed over a period of 16 years in one patient with WS. The data obtained on insulin secretion were assessed in this study. The patient was a 50-yr-old woman of consanguineous parentage. She presented with gray hair, cataracts, a beak-shaped nose and high-pitched voice. She was diagnosed as WS on the basis of her characteristic appearance. OGTT was performed 14 times during 9 admissions to our hospital. After ingestion of glucose, plasma glucose (PG) levels and immuno-reactive insulin (IRI) at 0, 30, 60, 90, 120 and 180 min were determined. PG levels during OGTT gradually increased during dietary therapy and, at the age of 48, insulin treatment was started [PG level at 120 min during OGTT at 46 yr (before treatment) was 1.5 times that at 34 yr]. Insulin secretion had also gradually decreased during the follow-up period (sum of IRI at 34 yr during OGTT post-treatment; 550.8 IU/ml, sum of IRI at 50 yr during OGTT post-treatment; 244.5 IU/ml). However, the insulinogenic indices were maintained at almost the same level value. Our results indicate that insufficient insulin secretion, which could not overcome insulin resistance, might play a crucial role in the pathophysiology and progression of diabetes in WS along with insulin resistance due to a post-receptor defect.

Connexin gene mutations in human genetic diseases

Rapid advances in understanding the molecular biology of the gap junctional proteins - connexins (Cx) - have revealed that these proteins are indispensable for various cellular functions. Recent findings that mutational alterations of Cx genes leads to several quite different human diseases provide additional evidence that these proteins possess several not yet fully understood functions. Many different mutations of Cx32 have been found in the hereditary peripheral neuropathy - X-linked Charcot-Marie-Tooth syndrome and several mutations of Cx26 and Cx31 have been detected in deafness. Individual mutations of Cx46, Cx50 and Cx43 have been found in cataract or heart malformations. In this review, we analyzed the functional importance of mutations of different Cx described in different human diseases. Topological comparison of mutations in different Cx species has revealed several hot spots, where mutations are common for two different Cx or diseases. The value of Cx mutations associated with diseases for understanding Cx functions is discussed.