Biomedical subjects

S Seto

Publications and source records attributed to S Seto.

At least 19 recordsLinked to original sources

PubMed2007

Low-grade central osteosarcoma mimicking fibrous dysplasia: a report of two cases.

Low-grade central osteosarcoma is an unusual variant of conventional osteosarcoma. We present here two rare cases of low-grade central osteosarcoma resembling fibrous dysplasia. A 24-year-old woman diagnosed as fibrous dysplasia was treated with intra-lesional excision and curettage of the tumor but tumor recurred at 4 months after surgery. Distal femoral en-bloc resection was performed followed by arthroplasty with mega-prosthesis of the knee. A 57-year-old man diagnosed as central osteosarcoma was treated with wide excision of the tumor, followed by reconstruction with the vascularized fibula graft combined with an autogenous irradiated bone graft. Because of the difficulty in distinguishing low-grade central osteosarcoma from a benign lesion, open biopsy is needed to obtain a large tumor sample. Careful clinical and pathological evaluation is required to obtain a definite diagnosis. The treatment of low-grade central osteosarcoma is en-block resection with wide surgical margins.

Adult↗

PubMed2006

Transient antiphospholipid antibodies associated with acute infections in children: a report of three cases and a review of the literature.

We describe two previously healthy children who had multiple ecchymoses several days after acute infection. In both cases, the prothrombin time (PT) and the activated partial thromboplastin time (APTT) were prolonged. Further examinations revealed the presence of lupus anticoagulant (LA), phosphatidylserine-dependent antiprothrombin antibodies (aPS/PT), and low serum complement. In both cases, we confirmed the presence of a serum immune complex. The patients' symptoms improved spontaneously within 1 week, and all laboratory data normalized within several months. We also describe another asymptomatic case positive for LA and aPS/PT presumably associated with cytomegalovirus infection. The prevalence of transient antiphospholipid antibodies associated with viral infections in children must be much higher than we expected. We have to take it into consideration when we see abnormal coagulation results, but the occurrence of significant bleeding symptoms is rare.

Acute Disease↗

PubMed2002

The effects of body mass index on age at menopause.

OBJECTIVE: We examined which of body mass index (BMI, kg/m(2)), serum cholesterol (mg/dl), or systolic blood pressure (SBP, mm Hg) affected age at natural menopause. DESIGN: A population-based follow-up program. METHODS: We determined the age at natural menopause in 1136 women followed biennially since their first examination in 1958-1959 through the 16th examination in 1988-1989. Four-hundred and ninety-three naturally menopausal women were classified into three groups by BMI, serum cholesterol and SBP measurement levels at age 40 or 41 y: the upper 25%, middle 50%, and lower 25%. We then studied whether there was a difference in age at menopause among the three groups thus classified. The 1136 natural menopausal women were also classified as early (n=454; 45-49 y at menopause (48.3+/-1.2 y)) or late (n=682; >or=50 y at menopause (52.3+/-1.6 y)) menopausal and compared for premenopausal trends in BMI, serum cholesterol and SBP in the early and late menopausal women by means of a longitudinal data analysis model. RESULTS: When women were classified into the three groups based on a BMI that was measured at 40 or 41 y, age at menopause in the upper 25% (50.4+/-2.8 y) was significantly higher (P<0.05) than that in the lower 25% (49.7+/-2.8 y). The entire premenopausal trend in BMI in late menopausal women shifted upward compared to that in early menopausal women. On the other hand, the premenopausal trend more than 4 y before menopause in serum cholesterol and the entire premenopausal trend in SBP in late menopausal women were identical to those in early menopausal women. CONCLUSION: Among the variables studied, only BMI is related to age at menopause, and the greater the BMI, the later the age at menopause.

Adult↗

PubMed2002

How HIV infected haemophiliacs in Japan were informed of their HIV-positive status.

The purpose of this study is to find out how HIV-infected haemophiliacs were informed and notified of their HIV infection. Self-reporting questionnaires were mailed to approximately 500 patients, about one half of the haemophiliac patients with HIV in Japan. The response rate was about 57% (n=283); and 270 (male=269) patients, apart from secondary and tertiary infected patients, were eligible as subjects for the study. The mean age was 31.2 +/- 9.9 years. Of these subjects, approximately 60% did not receive explanation regarding the risk of HIV infection via unheated blood products. More than 60% did not receive notification until 1990, or five years after the test became available in Japan. Contents of the explanations being given at the time of notifications were poor. In this paper, some problems of notifications of medically induced HIV are discussed, and the lack or delay of explanation/notification is concluded to be a consequence of the paternalistic attitudes of Japanese physicians and the iatrogenic nature of HIV infection.

Adolescent↗

PubMed2001

Contribution of central amiloride-sensitive transport systems to the development of hypertension in spontaneously hypertensive rats.

This study was conducted to examine if central amiloride-sensitive transport systems are involved in the development and/or maintenance of hypertension in spontaneously hypertensive rats (SHR). Either amiloride (75 microg/60 microl/day) or artificial cerebrospinal fluid (aCSF, 60 microl/day) was infused centrally (i.c.v.) for 4 weeks to development (4-5-weeks-old) and maintenance (10-12-weeks-old) phases of hypertension in SHR. In development phase, amiloride i.c.v. (n=14) blunted the elevation of blood pressure (BP) compared to aCSF i.c.v. (n=9) (amiloride vs. aCSF; after 3 weeks of i.c.v., 146+/-3 vs. 166+/-5 mmHg, P<0.001). The difference of BP at 3 weeks of i.c.v. was canceled after ganglionic block with hexamethonium (115+/-4 vs. 117+/-5 mmHg). Further, pressor responsiveness to norepinephrine was augmented in amiloride i.c.v. rats (amiloride, n=11 vs. aCSF, n=6; %Delta BP at 800 ng/kg/min.: 16.9+/-1.3 vs. 10.8+/-1.4 mmHg, P<0.05) and this augmentation disappeared after ganglionic block. Pressor responsiveness to angiotensin II and cumulative sodium balance did not differ in the two groups. Intravenous administration of amiloride at the same dose did not attenuate the development of hypertension. On the other hand, in maintenance phase, amiloride i.c.v. by the same protocol as in development phase had no effect on BP in SHR. Also, amiloride i.c.v. did not affect BP in normotensive Wistar-Kyoto rats. These results suggest that central amiloride-sensitive transport systems are involved in the development, but not in the maintenance, of hypertension in SHR through the modulation of autonomic neural mechanisms.

Amiloride↗

PubMed2001

Novel seco cyclopropa[c]pyrrolo[3,2-e]indole bisalkylators bearing a 3,3'-arylenebisacryloyl group as a linker.

We synthesized the novel seco cyclopropa[c]pyrrolo[3,2-e]indole (CPI) bisalkylators and evaluated their antitumor activity. Among these derivatives, 11a (AT-760), in which the two seco 3-methoxycarbonyl-2-trifluoromethyl CPI (MCTFCPI) moieties are connected with a 3,3'-(1,4-phenylene)bisacryloyl group, was found to exhibit more potent cytotoxicity and antitumor activity against HeLaS3 human uterine cervix carcinoma cells and Colon 26 adenocarcinoma cells, respectively, than 8 (bizelesin, U-77,779). It also appeared that compound 11a exhibits improved in vivo efficacy in the human colon CX-1 model when compared to either compound 8 or mitomycin C (MMC). Efficacious doses for 11a were found to be 2-fold lower than those for 8.

Animals↗

PubMed2001

Effects of age at menopause on serum cholesterol, body mass index, and blood pressure.

Pre- and postmenopausal cholesterol (mg/dl), body mass index (BMI; kg/m(2)), and systolic blood pressure (SBP; mmHg) levels were compared in three age-at-time-of-menopause (ATM) groups to examine the relationship between the three risk factors and age ATM. Cholesterol, BMI, and SBP levels recorded 4 years prior to and 8 years after menopause were examined and increases in these risk factors between the two measurements were noted. The three age groups were: group A (n=49; age ATM [44+/-1]<45), group B (n=395; 45< or =age ATM [48+/-1]<50), and group C (n=578; age ATM [52+/-2]> or =50). Cholesterol levels in premenopausal groups A (169+/-31 mg/dl, 40 years) and B (174+/-31, 44 years) were lower than those in group C (179+/-30, 48 years) (0.05< or =P<0.1 and P<0.05). Because, the increases in cholesterol were greater in group A (41+/-28 mg/dl) than in groups B (32+/-28) and C (29+/-28) (0.05< or =P<0.1 and P<0.05), cholesterol levels were identical among groups despite age differences upon reaching the postmenopause phase: group A (210+/-34, 51 years), group B (206+/-35, 56 years) and group C (208+/-35, 60 years). BMI and SBP increases were not different in groups A, B, and C. Differences in BMI and SBP levels among groups in order of premenopausal age were still observed after menopause. These data suggest that the greater increase in cholesterol associated with early menopause may be related to a higher prevalence of ischemic heart disease (IHD) in younger menopausal women.

Aging↗

PubMed2001

The prevalence, incidence and prognostic value of the Brugada-type electrocardiogram: a population-based study of four decades.

OBJECTIVES: We sought to demonstrate the prevalence, incidence and prognostic value of the Brugada-type electrocardiogram (ECG) in a general population. BACKGROUND: The Brugada syndrome is characterized by evidence of right bundle branch block and ST segment elevation in the right precordial leads, as well as sudden death caused by ventricular fibrillation. However, the natural history of the Brugada-type ECG remains unclear. METHODS: We investigated 4,788 subjects (1,956 men and 2,832 women) who were <50 years old in 1958 and had undergone biennial health examinations, including electrocardiography, through 1999. The Brugada-type ECG was defined as a terminal r' wave in lead V(1) and ST segment elevation > or =0.1 mV in leads V(1) and V(2). Unexpected death was defined as sudden death or unexplained accidental death. RESULTS: There were a total of 32 Brugada-type ECG cases; the prevalence and incidence were 146.2 in 100,000 persons and 14.2 persons per 100,000 person-years, respectively. The incidence was nine times higher among men than women, and the average age at presentation was 45 +/- 10.5 years. The Brugada-type ECG appeared intermittently in most cases and was found in 26% of subjects who died unexpectedly. Cox survival analysis revealed that mortality from unexpected death was significantly higher in subjects with a Brugada-type ECG than in control subjects (p < 0.01). Unexpected deaths were more frequent among subjects with the Brugada-type ECG who had a history of syncope (p < 0.05). CONCLUSIONS: The Brugada-type ECG is not a very rare condition in the adult Japanese population. Subjects with a Brugada-type ECG have an increased risk of unexpected death.

Adult↗

PubMed2001

Alteration of antioxidants during the progression of heart disease in streptozotocin-induced diabetic rats.

Involvement of oxidative stress is implicated in the progression of complication of diabetes mellitus. With respect to heart diseases, we have studied role of oxidative stress/antioxidants using rats treated with streptozotocin to induce diabetes (DM). Hemodynamic and echocardiographic measurements showed thickening of the wall and an increase in the internal dimension of the left ventricle (LV) in DM rats at 8th week. Decrease in diastolic posterior wall velocity and rate of LV pressure change, and increase in LV end diastolic pressures also proved cardiac dysfunction. These changes were further developed in DM rats after 12 weeks. Utilizing rat hearts at 8th and 12th weeks, the following estimations were performed. There was a decrease in the activity of Mn-superoxide dismutase (SOD), suggesting abnormal mitochondrial metabolism of reactive oxygen species. The level of glutathione (GSH) decreased concomitant with a decrease in the expression of gamma-glutamylcysteine synthetase (gamma-GCS). The expression of transforming growth factor-beta1 (TGF-beta1), known as a growth factor and a suppressor of GSH synthesis, elevated in DM rat hearts. Immunohistochemical estimation showed an increase in type IV collagen in DM hearts. Collectively, it was suggested a linkage between mitochondrial damage to generate reactive oxygen species and inactivation of Mn-SOD and elevation of the expression of TGF-beta1 to lead suppression of GSH synthesis and induction of fibrous change for the consequent cardiac dysfunction in DM.

Animals↗

PubMed2001

Visualization of the attachment organelle and cytadherence proteins of Mycoplasma pneumoniae by immunofluorescence microscopy.

A method was developed for protein localization in Mycoplasma pneumoniae by immunofluorescence microscopy. The P1 adhesin protein was revealed to be located at least at one cell pole in all adhesive cells, as has been observed by immunoelectron microscopy. Cell images were classified according to P1 localization and assigned by DNA content. Cells with a single P1 focus at one cell pole had a lower DNA content than cells with two foci, at least one of which was positioned at a cell pole. Those with one focus at each cell pole had the highest DNA content, suggesting that the nascent attachment organelle is formed next to the old one and migrates to the opposite cell pole before cell division. Double staining revealed that the accessory proteins for cytadherence-HMW1, HMW3, P30, P90, P40, and P65-colocalized with the P1 adhesin in all cells. The localization of cytadherence proteins was also examined in cytadherence-deficient mutant cells with a branched morphology. In M5 mutant cells, which lack the P90 and P40 proteins, HMW1, HMW3, P1, and P30 were focused at the cell poles of short branches, and P65 showed no signal. In M7 mutant cells, which produce a truncated P30 protein, HMW1, HMW3, P1, P90, and P40 were focused, and P65 showed no signal. In M6 mutant cells, which express no HMW1 and a truncated P30 protein, the P1 adhesin was distributed throughout the entire cell body, and no signal was detected for the other proteins. These results suggest that the cytadherence proteins are sequentially assembled to the attachment organelle with HMW1 first, HMW3, P1, P30, P90, and P40 next, and P65 last.

Adhesins, Bacterial↗

PubMed2001

Correlation between fatty liver and coronary risk factors: a population study of elderly men and women in Nagasaki, Japan.

The relation between fatty liver, detected by ultrasonography as a marker of visceral fat accumulation, and coronary risk factors was studied in 810 elderly men and 1,273 elderly women in Nagasaki, Japan from 1990 to 1992. The prevalence of fatty liver was 3.3% in the male and 3.8% in the female non-obese participants (BMI, body mass index < 26.0 kg/m2) and 21.6% in the male and 18.8% in the female obese participants (26.0 kg/m2 < or = BMI). Fatty liver was significantly (p < 0.01) related to hypercholesterolemia and hypertriglyceridemia in the men and to hypertension, hypercholesterolemia, low-HDL cholesterol, hypertriglyceridemia and diabetes mellitus or impaired glucose tolerance (DM+IGT) in the women independent of age, obesity, smoking and drinking. Non-obesity with fatty liver, rather than obesity with or without fatty liver, had the highest odds ratio for hypertension and low-HDL cholesterol in the men and for hypercholesterolemia, low-HDL cholesterol, hypertriglyceridemia and DM+IGT in the women. The prevalence of fatty liver is the same in elderly men and women, and fatty liver is an independent correlate of coronary risk factors in the elderly.

Aged↗

PubMed2000

Tissue factor expression in human colorectal carcinoma: correlation with hepatic metastasis and impact on prognosis.

BACKGROUND: It has been suggested that tissue factor (TF) plays an important role in tumor metastasis. Its expression in sarcoma cells was reported to up-regulate the vascular endothelial growth factor (VEGF) gene and thereby enhance tumor angiogenesis, which is essential to tumor metastasis. Although many malignant tumors have been reported to express this protein constitutively, recent clinical studies have focused mainly on the correlations among TF expression, tumor progression, and histologic grade. Therefore, to address the role of TF and the underlying mechanism of hematogenous metastasis of colorectal carcinoma, the authors analyzed the correlations among TF expression, hepatic metastasis, and VEGF gene expression in surgical specimens. Furthermore, they analyzed the prognostic significance of TF expression with respect to overall patient survival. METHODS: Expression of TF and VEGF genes in 67 advanced colorectal carcinoma specimens was studied by immunohistochemistry and Northern blot analysis, respectively. The correlations among TF expression, hepatic metastasis, and other factors were analyzed with univariate and multivariate statistics. Survival rates were calculated using the Kaplan-Meier method. RESULTS: Univariate and multivariate analyses showed TF expression to be a significant (P = 0.0001) and independent risk factor for hepatic metastasis, whereas a weak but insignificant correlation was observed between TF and VEGF gene expression. The outcomes in the TF positive group were significantly worse in all cases (P = 0.0001) and in the cases without synchronous hepatic metastasis (P = 0.0156). CONCLUSIONS: Although the precise mechanisms are unknown, TF expression is a suitable indicator of both hepatic metastasis and prognosis for colorectal carcinoma patients.

Aged↗

PubMed2000

Activated protein C prevents multiple organ injury following extensive hepatectomy in cirrhotic rats.

BACKGROUND/AIMS: Extended hepatectomy for cirrhotic liver in patients with hepatocellular carcinoma often triggers posthepatectomy liver failure. It has been shown that the microcirculatory disturbance caused by microthrombus formation and sinusoidal endothelial cellular injury is one of the causes of post-hepatectomy liver dysfunction. We therefore investigated the effect of activated protein C (APC), a potent antithrombotic serine protease with anti-inflammatory effects, on posthepatectomy liver dysfunction and multiple organ injury in cirrhotic rats. METHODS/RESULTS: Dimethylnitrosamine-induced cirrhotic rats underwent 70% hepatectomy and received lipopolysaccharide (200 microg/kg) 48 h later to prepare a lethal posthepatectomy acute liver failure model. APC (1500 U/kg), given intravenously 15 min before and 1 h after endotoxin challenge, attenuated liver dysfunction and decreased serum tumor necrosis factor-alpha concentration. APC significantly improved the survival rate of rats at 12 h after endotoxin challenge. Histological examination revealed that APC treatment inhibited not only intrasinusoidal fibrin deposition and massive hepatocellular necrosis but also pulmonary injury and glomerular fibrin deposition. Immunohistochemically, expression of intercellular adhesion molecule-1 on sinusoidal cells and renal glomeruli was decreased in the APC-treated animals. CONCLUSIONS: APC administration prevented acute liver dysfunction and attenuated multiple organ injury following extended hepatectomy in cirrhotic rats, possibly via anticoagulant and anti-inflammatory effects.

Animals↗

PubMed2000

A 15-year longitudinal follow-up study of heart rate and heart rate variability in healthy elderly persons.

BACKGROUND: Few researchers have conducted heart rate (HR) studies in healthy very elderly subjects aged 70 years or older, and there are no longitudinal follow-up studies in this population. The objective of this study was to evaluate long-term changes in HR and heart rate variability (HRV) with aging in healthy elderly persons by means of comparison between two Holter monitor recordings obtained at an interval of 15 years. METHODS: The study population consisted of 15 healthy elderly persons (10 women and 5 men) aged 64 to 80 years (mean 70 +/- 4.1) at the first recording, and 79 to 95 years old (mean 85 +/- 4.1 years) at the second recording 15 years later. Nighttime (midnight to 5 AM) and daytime (noon to 5 PM) HR and HRV were obtained, and paired t tests were performed to assess the differences in each parameter of nighttime and daytime HR and HRV between the two (15-year interval) Holter monitor recordings. RESULTS: The results of the t-test comparisons were as follows: there was a significant increase in minimal, maximal, and average HRs (nighttime, p < .01; daytime, p < .05, respectively). On the other hand, with regard to HRV, there was a significant nighttime decrease in the SDNN index (mean of standard deviations of normal RR intervals between adjacent QRS complexes resulting from sinus node depolarizations for all 5-minute segments) (p = .0086), and a significant daytime increase in the NN50 (number of adjacent normal RR intervals >50 milliseconds) per hour (p = .0425). Moreover, there was a significant decrease in the low-frequency (LF) component (nighttime, p = .0151; daytime, p = .0032), and a significant decrease in the LF/HF ratio (nighttime, p = .0270; daytime, p = .0371), but there was no significant change in the nighttime or daytime high-frequency (HF) component. CONCLUSIONS: HR increased with age over the 15-year period in the healthy elderly persons. As for concurrent changes in HRV, however, the parameters of sympathetic modulation decreased, and the parameters of parasympathetic modulation were unchanged or slightly increased.

Aged↗

PubMed1999

Hepatocyte growth factor supply accelerates compensatory hypertrophy caused by portal branch ligation in normal and jaundiced rats.

BACKGROUND: Hepatocyte growth factor (HGF), first identified as the most potent mitogen for hepatocytes, significantly stimulates liver regeneration after hepatectomy. In this report, we examined whether HGF is also useful in accelerating compensatory hypertrophy caused by portal branch ligation in normal and jaundiced rats. MATERIALS AND METHODS: Normal and reversible obstructive jaundiced rats underwent portal ligation of the left lateral and median branches, which supply approximately 70% of the total volume of the liver. Simultaneously, the animals were continuously treated with either recombinant human HGF (rhHGF) or vehicle alone via an intraperitoneally implanted osmotic pump. Two and four days after portal ligation, the degree of compensatory hypertrophy in unoccluded lobes was examined by measuring the wet weight ratios of the unoccluded lobes to the whole liver and the 5-bromo-2'-deoxyuridine labeling index of hepatocytes in each group. RESULTS: The HGF treatment significantly increased the wet weight ratios and the DNA synthesis in nonoccluded lobes 2 and 4 days after portal ligation in both normal and jaundiced rats. Moreover, rhHGF supply promptly decreased serum total bilirubin level in jaundiced rats. CONCLUSIONS: Continuous rhHGF administration not only accelerates compensatory hypertrophy in normal and jaundiced rats but also ameliorates hyperbilirubinemia in jaundiced rats.

Adaptation, Physiological↗

PubMed1999

Protection by various deoxynucleosides against deoxyadenosine-induced DNA damage in adenosine deaminase-inactivated lymphocytes.

Adenosine deaminase deficiency is an inborn error resulting in immunodeficiency. The pathogenesis of the lymphopenia is not fully understood. Intracellular increases in dATP in the absence of deamination retard DNA repair in human resting lymphocytes and results in the slow accumulation of DNA strand breaks. We focused on the relationship between DNA damage and DNA precursor pools in cultures of deoxycoformycin-treated, ADA-inhibited resting lymphocytes. The addition of 10 microM deoxyadenosine led to a substantial number of DNA strand breaks within 12 h, breaks equivalent to those which occur with about 190 rad irradiation. Addition of any of the other deoxynucleosides used partially prevented this dAdo-induced DNA damage and promoted DNA repair. However, the preventive effects did not correlate inversely with intracellular dATP levels. Resting lymphocytes have very small dNTP pools. Treatment with dAdo slightly reduced dTTP and dCTP. Three kinds of deoxynucleosides, other than dAdo, restored or raised the corresponding dNTP level but the pool imbalance was only minimally corrected. Regarding the toxic effects of dAdo in ADA deficiency, not only dATP levels but also dNTP pool balance has a crucial role in the pathogenesis. Pool sizes of dTTP, dCTP, and possibly dGTP must be maintained at normal levels, if dAdo-induced DNA damage is to be avoided.

Adenosine Deaminase Inhibitors↗

PubMed1999

Involvement of receptor-type tyrosine kinase gene families in cardiac hypertrophy.

OBJECTIVE: The activation of protein tyrosine kinases (PTKs) has been postulated to be involved in cell differentiation and proliferation. To elucidate the involvement of tyrosine kinase genes in normal and pathological conditions, we analysed the expression patterns of receptor-type PTKs in the normal and hypertensive hypertrophied heart in rats. MATERIALS AND METHODS: Hypertrophied and normal rat hearts were obtained from hypertensive rats; deoxycorticosterone acetate (DOCA)-salt and 2 kidney-1 clip (2K-1C), and their sham-operated rats, respectively. A reverse transcription-polymerase chain reaction (RT-PCR) was performed using degenerated primers which were designed from highly conserved regions in the catalytic domains of receptor-type PTKs. The PCR products were ligated into a sequence vector, and subcloned by transforming bacteria. To compare the expression level of these PTK mRNAs in the normal and hypertrophied heart, we performed semi-competetive RT-PCR and immunohistochemical and Western blot analyses. RESULTS: Nucleotide sequencing of approximately 80 clones of PTKs revealed 10 receptor-type, five nonreceptor-type and two unknown types in the rat heart. Tie-2/Tek, Ryk, insulin-like growth factor-I receptor were abundantly expressed in the rat heart as members of receptor-type PTKs. Immunohistochemistry and RT-PCR demonstrated the presence of platelet-derived growth factor (PDGF)-alpha receptor, PDGF-beta receptor and fibroblast growth factor-3 receptor in both normal and hypertrophied hearts. We also confirmed the presence of Flt-1, KDR/FIk-1, and their ligand vascular endothelial growth factor, c-Met and its ligand hepatocyte growth factor (HGF), and Tie-1, Tie-2/Tek by immunohistochemistry and RT-PCR. The coexpression of cardiac HGF and c-Met in hypertrophied hearts, especially in 2K-1 C rats, was induced more intensively than that in DOCA-salt rats. CONCLUSION: These findings suggest that HGF/c-Met interactions may play an important role in cardiac hypertrophy and remodeling, probably as a result of the activation of the local renin-angiotensin system.

Animals↗

PubMed1999

Partitioning, movement, and positioning of nucleoids in Mycoplasma capricolum.

The nucleoids in Mycoplasma capricolum cells were visualized by phase-combined fluorescence microscopy of DAPI (4', 6-diamidino-2-phenylindole)-stained cells. Most growing cells in a rich medium had one or two nucleoids in a cell, and no anucleate cells were found. The nucleoids were positioned in the center in mononucleoid cells and at one-quarter and three-quarters of the cell length in binucleoid cells. These formations may have the purpose of ensuring delivery of replicated DNA to daughter cells. Internucleoid distances in binucleoid cells correlated with the cell lengths, and the relationship of DNA content to cell length showed that cell length depended on DNA content in binucleoid cells but not in mononucleoid cells. These observations suggest that cell elongation takes place in combination with nucleoid movement. Lipid synthesis was inhibited by transfer of cells to a medium lacking supplementation for lipid synthesis. The transferred cells immediately stopped dividing and elongated while regular spaces were maintained between the nucleoids for 1 h. After 1 h, the cells changed their shapes from rod-like to round, but the proportion of multinucleoid cells increased. Inhibition of protein synthesis by chloramphenicol induced nucleoid condensation and abnormal positioning, although partitioning was not inhibited. These results suggest that nucleoid partitioning does not require lipid or protein synthesis, while regular positioning requires both. When DNA replication was inhibited, the cells formed branches, and the nucleoids were positioned at the branching points. A model for the reproduction process of M. capricolum, including nucleoid migration and cell division, is discussed.

Bacterial Proteins↗