Biosynthesis of formycin. Role of certain amino acids in formycin biosynthesis.
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Biomedical subjects
Publications and source records attributed to S Iwamoto.
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Two truncated mRNAs, in contrast to the full length of mRNA associated with the glycophorin A gene (GpA-TI, GpA-TII), were isolated from erythroid cells cultured by the selective two-phase liquid culture system for erythroid progenitors in peripheral blood from a normal individual. The GpA-TI mRNAs displayed a direct transition from exon I to exon III, so that the deletion of exon II resulted in the deletion of 33 amino acids encoded by this exon. Furthermore, the GpA-TII showed two direct transitions from exon I to exon III and from exon III to the exon V of the GpA gene. This mRNA lacked both exons II and VI, resulting in the deletion of 46 amino acids. Is is concluded that these truncated mRNAs are transcribed from the same gene as the GpA gene and correspond to splicing isoforms lacking different exons.
To examine the biliary excretion of trichloroethylene (TRI) and its metabolites, we carried out various experiments with TRI and its metabolites, i.e., chloral hydrate (CH), free-trichloroethanol (F-TCE) and trichloroacetic acid (TCA), using anesthetized dogs. The amount of biliary excretion was significantly increased with the administration of CH and F-TCE, whereas it remained at control levels with the administration of TRI and TCA. The substances excreted into bile were conducted in the form of conjugated-TCE (Conj-TCE) in over 90% of the CH, F-TCE and TRI administration groups. About 95% of these Conj-TCE were conjugated with glucuronic acid. The cumulative excretion ratios of substances and metabolites to dose were 20% for CH and F-TCE, and about 1% for TCA and TRI 2 h after administration.
For DNA in solution, there have been two methods for measuring the helical periodicity. One method examines the ladder of discrete bands formed in the electrophoretic pattern of supercoiled DNA. Such a ladder is assumed to reflect the set of differently linked covalently closed molecules. The other method measures the lengths of partial nuclease digestions of DNA segments affixed to flat surfaces. Neither method, however, is able to measure the absolute handedness. X-ray diffraction of DNA oligonucleotides can determine the handedness, but the DNA must necessarily be crystallized. We have developed a new method for determining the helical parameters of a segment of DNA in solution. It is the first non-crystallographic method that can directly determine both the helical periodicity and the absolute handedness of DNA. The results obtained using this method are consistent with the classical Watson-Crick right-handed double helical model.
Human myelogenous leukaemic cells can be induced to differentiate into the monocyte/macrophage pathway by protein inducers called differentiation inducing factors (DIF) in conditioned media of mitogen-stimulated human peripheral blood leukocytes. However, human DIF has not yet been well characterized. DIF is known to be a T-cell lymphokine, as it can be obtained from the T-cell line HUT-102 and can be partially purified from medium conditioned by phytohaemagglutinin (PHA)-stimulated lymphocytes. We found that monocytes also produce factor(s) that induce differentiation of human myelogenous leukaemia cell lines to cells with macrophage-like characteristics. This factor(s) has activity different from that of colony-stimulating factor(s) or interferons. We have now purified a DIF to homogeneity from medium conditioned by PHA-stimulated leukocytes using a human myeloblastic leukemia cell line, ML-1, as target cells. The purified DIF has a relative molecular mass (Mr) of approximately 17,000, with an NH2-terminal sequence the same as that of human tumour necrosis factor (TNF). Recombinant human TNF (rHuTNF) induces differentiation of ML-1 cells and an anti-pDIF monoclonal antibody can neutralize both differentiation inducing activity and cytotoxic activity of DIF and rHuTNF. The findings indicate that one of the DIF(s) produced by leukocytes is probably TNF.
Cord blood transplantation (CBT) has been increasingly used to treat patients with hematological diseases, but active immunizations for patients have not been described. Patients certainly need immunizations following CBT, since transplanted cord blood is naive. The authors previously reported successful hematopoietic reconstitution following cord blood transplantation from an HLA-matched sibling in a transfusion-dependent child with Diamond-Blackfan anemia. No graft-versus-host disease, either acute or chronic, has been observed so far. Here, the authors report that immunological recovery of the patient has been rapid shortly after CBT and immunization has been done successfully. Vaccines (diphtheria, pertussis, tetanus, rubella, measles, and BCG) were administered during 22-34 months post-transplant. Seroconversion to these vaccines was excellent without significant adverse effects. These results indicate that both toxoid and live vaccines have been safely administered in the patient who underwent related cord blood transplantation.
A 59 year old man with cirrhosis presented with encephalopathy and hyper-ammonaemia. T1 weighted magnetic resonance imaging demonstrated a large void tubular structure connecting the right posterior portal vein branch and the inferior vena cava through the right hepatic lobe inferiorly, and cine-mode imaging showed a flow within this channel. Clearly in this patient a significant portion of the portal venous blood was being shunted into the inferior vena cava, causing encephalopathy. The exact origin of this channel is not known, but several possibilities are discussed. It is also predicted that similar previously unknown large intrahepatic shunts will be discovered increasingly with the availability of modern imaging techniques.
BACKGROUND: Intraductal papillary-mucinous carcinoma of the pancreas is a new diagnostic term proposed by the 1996 World Health Organization classification of the exocrine pancreas. So far, there have been only a few reports concerning its cytologic findings, especially in noninvasive cases. CASES: The clinical and cytohistologic findings in two cases of noninvasive intraductal papillary-mucinous carcinoma of the pancreas were reviewed. Cytologic specimens were obtained from pure pancreatic juice in the dilated main pancreatic duct during the operation (case 1) and during endoscopic retrograde pancreatography (ERP) (case 2). Both cases showed three-dimensionally or individually scattered tumor cells with an increased nuclear/cytoplasmic ratio and prominent nucleoli. CONCLUSION: Our cases suggest that pancreatic juice cytology during ERP or surgery is useful in diagnosing pancreatic cancers and that it may detect noninvasive intraductal papillary-mucinous carcinoma of the pancreas.
For clinical islet cell transplantation, short-term storage of islet cells is likely to be necessary, and it is imperative that the islet cells be kept as viable as possible during the period. However, there are little data on which preservative solutions are most suitable for the storage of islet cells after isolations or before transplantation. To estimate islet cell viability and transplantation success rate in the present study, adenylylcyclase activity was measured with a rapid new fluorometric assay in rat islet cells prior to transplantation, because cAMP plays an essential role in determining islet beta-cell viability and responsiveness to various hormonal stimuli. Adenylylcyclase activity was measured in islet cells stored for different periods of time 0, 3, 16, 24, 48, 96 h) and in different preservative solutions. Approximately 1,000 islet cells from each preservation group using University of Wisconsin (UW) solution were transplanted to streptozotocin-induced diabetes mellitus (DM) rats. Transplant success was evaluated by measuring blood glucose levels. Preoperative adenylylcyclase activity was compared with posttransplant islet cell function. The adenylylcyclase activity of UW solution was significantly higher than that of Euro-Collins solution and lactate-Ringer's solution through the different preservation time periods. Preoperative adenylylcyclase activity correlated well with posttransplant islet cell function in a rat model of DM. We conclude that adenylylcyclase activity can be used as a marker to assess islet cell viability as well as differences in preservation media and may predict islet cell transplant success.
OBJECTIVES: An increasing number of lifestyle disorders have emerged in response to the rapid urbanization that has occurred in Thailand. Recently, leptin resistance has been nominated as a possible marker for the onset of metabolic disorders in Asian countries. The research aimed to assess the relationship between leptin-resistance and environmental and/or genetic factors by comparing urban and rural inhabitants in Thailand. METHODS: A total of 212 age- and sex-matched subjects from an urban area (Bangkok) and from rural areas (Sai Noi) participated in the study. Anthropometric measurements, blood biochemistry, single nucleotide polymorphism analyses, and interviews concerning lifestyles and dietary habits were conducted individually. Backward elimination multiple regression analyses and least trimmed sum of square methods were used to estimate the effects of possible factors. RESULTS: A transition of staple food from rice to bread (decreased rice intake; p < 0.01 and increased bread intake; p < 0.05) was significant in urban areas. Leptin levels were higher in urban groups, with a significant difference in women (p < 0.001 in women and p = 0.06 in men), but not in men. Predictors selected for leptin-resistance in women were genotypes of UCP2, PPARg2, bread intake, living area, and smoking habit (r = 0.510); in men, genotypes of UCP2 and UCP3p, smoking habit, and rice intake (r = 0.315). CONCLUSIONS: Urban women with del/del type of UCP2 exhibited significant leptin resistance. A combination of urbanization and UCP2 genotype were considered to be responsible.
The individual roles of two types of TNF receptors (55 kDa and 75 kDa) in induction of differentiation of human myeloblastic leukemia ML-1 cells were investigated using three monoclonal antibodies. The antibody htr-9, which recognizes the 55 kDa receptor, induced differentiation of ML-1 cells. Utr-1, which recognizes the 75 kDa receptor, blocked 125I-TNF binding by about 80% and inhibited by about 80% the TNF-induced NBT reducing activity. Htr-5 recognizes the 55 kDa receptor, blocked 125I-TNF binding by about 20% and inhibited by about 60% the TNF-induced NBT reducing activity. The data suggest that either of the two TNF receptors alone can mediate signals for the differentiation of ML-1 cells, and that simultaneous stimulation of both receptors will induce differentiation more effectively.
A 48-year-old male had autosomic dominant polycystic kidneys with dimensions, to the best of our knowledge, never previously reported; the right kidney weighed 15,100 g and measured 53 x 33 x 9cm and the left one 10.200 g and 46 x 21 x 7cm, with cysts measuring up to 14cm in diameter. Nephrectomy was done to control persistent hematuria and to relief disconfort caused by the large kidneys. The renal function is stable four years after transplantation.
To evaluate the effects of dietary fats on breast cancer growth and metastasis, KPL-1 human breast carcinoma cells which have a propensity for axillary lymph node metastasis when inoculated into the thoracic mammary fat pad of female nude mice were examined. The mice were fed one of three semipurified diets containing 9.5% eicosapentaenoic acid plus 0.5% linoleic acid (EPA diet), 10% linoleic acid (LA diet), or 9.5% palmitic acid plus 0.5% linoleic acid (PA diet), or commercial laboratory chow containing 8.5% fat of which 4.1% was LA, 1.1% was PA, 0.06% was EPA, and 3.24% was other (Standard diet) starting 19 days before tumor cell inoculation and continuing until the end of the experiment (43 days after tumor cell inoculation). The tumor growth was faster and at a higher incidence in the mice fed the LA diet, and much slower and at a lower incidence in the EPA diet group compared with the mice fed the PA or Standard diet; the two separate experiment demonstrated identical results. The differences in tumor weight between the LA and PA groups and between the PA and EPA groups were significant (P < 0.05, respectively) at the termination of the experiment; the differences were due to different tumor cell proliferation rates. In an in vitro MTT assay, fatty acids showed direct stimulatory or inhibitory effects on the KPL-1 cells. Lymph node metastasis was seen in the LA and Standard diet groups, whereas it was not seen in the PA or EPA groups. The body weights were significantly lighter in the LA and EPA groups compared with the PA and Standard diet groups (P < 0.05, respectively). The results indicate that the EPA diet produced a reduction in tumor cell growth and metastasis whereas the LA diet had an enhancing effect on these parameters; dietary fatty acids may thus have a direct role in the growth and metastasis of human breast carcinoma independent of their systemic effects.