Folded edge of turbulence in a pipe.

The results of an experimental investigation into the threshold boundary between laminar and disordered pipe flow are presented. Complex features have been uncovered using a highly refined experimental approach where an intermediate periodic state forms an integral part of the transition sequence. In accord with the suggestions produced by a numerical investigation, the boundary is found to be folded with a complicated structure. This raises important questions about accepted definitions of threshold amplitudes in this long-standing problem.

Thermoinduction of genes encoding the enzymes of gibberellin biosynthesis and a putative negative regulator of gibberellin signal transduction in Eustoma grandiflorum.

Eustoma grandiflorum Shinn requires vernalization for the induction of stem elongation and flowering. To investigate the role of gibberellins (GAs) in vernalization, the expression levels of genes encoding enzymes of GA biosynthesis, copalyl diphosphate synthetase, GA 20-oxidase and GA 3 beta-hydroxylase, were examined using two culitvars that show different responses to vernalization. The three genes were induced in a vernalization- and a cultivar-dependent manner. EgSPY, a putative negative regulator of GA signal transduction, was also induced during the vernalization period. The results suggest that the expression of the genes encoding GAs biosynthesis is regulated by vernalization. We postulate that EgSPY functions as a negative regulator of GA signal transduction during vernalization, inhibiting adventitious shoot elongation during vernalization.

Elevated sensitivity to gibberellin by vernalization in the vegetative rosette plants of Eustoma grandiflorum and Arabidopsis thaliana.

Changes in the sensitivity to gibberellin (GA) after vernalization were studied in the vegetative rosette of Eustoma grandiflorum and late flowering Arabidopsis thaliana mutant, fca-1. The sensitivity to GA after vernalization was monitored using the bolting rate of plants that were grown on a medium containing GA(3) or ancymidol. The bolting rates were higher in vernalized plants than non-vernalized plants when the same GA(3) concentration was used. There was a positive relationship between the duration of vernalization and the bolting rate in E. grandiflorum. In contrast, a negative relationship between the duration of treatment and bolting rate was found in the non-vernalized plants. In fca-1, the flowering time of vernalized plants was significantly reduced compared with the non-vernalized plants under various concentrations of GA(3) treatment. To elucidate whether this elevated sensitivity relates to the efficiency of GA signal transduction, we measured the transcript amounts of Expansin (Exp), which is up-regulated by GA, and GA20-oxidase (GA20ox) and GA3 beta-hydroxylase (GA3betahy), which are down-regulated by GA. The transcript amounts were estimated using the Taq-Man PCR system based on combinations of primers and probes that specifically detect the genes, and normalized by the transcript amount of ubiquitin gene measured as an internal standard. For each concentration of GA treatments examined, Expansin of both E. grandiflorum and A. thaliana was induced at a higher rate in the vernalized plants than in the non-vernalized plants. The expression of GA20ox and GA3betahy of E. grandiflorum decreased faster in the vernalized plants than the non-vernalized plants. We conclude that vernalization is a critical environmental cue not only for initiating GA biosyntheses in vegetative rosette, but also for elevating the GA sensitivity of the plants via a GA signal transduction pathway.

Association of glutathione with flowering in Arabidopsis thaliana.

In order to study the relationship between GSH and flowering, wild-type and late-flowering mutant, fca-1, of Arabidopsis thaliana were treated with L-buthionine sulfoximine (BSO), a specific inhibitor of GSH biosynthesis, under long-day conditions. BSO treatment of the fca-1 mutant starting at 17 d after imbibition promoted flowering. However, when the treatment was started at 12 d after imbibition, BSO treatment at 10(-4) M resulted in an inhibition of flowering. This inhibitory effect of BSO on flowering was abolished by GSH treatment at 10(-4) M, although GSH treatment at an increased concentration of 10(-3) M clearly delayed flowering. In contrast, BSO treatment of wild-type plants starting at 12 d after imbibition promoted flowering, whose effect was abolished by GSH application. In the fca-1 mutant, whose endogenous GSH levels were high, chilling treatment lowered the GSH levels and promoted flowering, as was the case in the BSO treatment. An A. thaliana mutant, cad2-1, which has a defect in GSH biosynthesis also exhibited late flowering. The late-flowering phenotype of this mutant tended to be strengthened by BSO and abolished by GSH treatment. These results suggest that flowering is associated with the rate of GSH biosynthesis and/or the levels of GSH in A. thaliana.

A Case of Reversed Ophthalmic Artery Flow without Occlusion of the Internal Carotid Artery.

Background: We report a case of reversed ophthalmic artery (OA) flow showing neither occlusion of the internal carotid artery (ICA) nor ophthalmic symptoms.Case: An 82-year-old man had transient blindness in both eyes. After left carotid endarterectomy, ophthalmic symptoms improved in the right and left eyes. Afterwards, he had a relapse in the left eye.Results: There was no unusual impression in the ophthalmic examinations, but color Doppler imaging showed reduced flow in the left OA, reversal of flow direction in the right OA. The central retinal artery (CRA) and short posterior ciliary arteries (SPCA) were not detected in the left eye but were detected in the right eye. Digital subtraction angiography demonstrated that the right OA was not contrasted with the right ICA, despite there being no stenosis or occlusion of the right ICA.Conclusions: We suggest that carotid surgery may affect the ocular circulation of the opposite side, and reversed OA flow as a collateral pathway from the external carotid artery may occur in the absence of carotid artery stenosis. Good circulation of the CRA and SPCA may preclude manifestation of ophthalmic symptoms even if the OA flow is reversed.

[A case of reversed ophthalmic artery flow without occlusion of the internal carotid artery].

BACKGROUND: We report a case of reversed ophthalmic artery (OA) flow showing neither occlusion of the internal carotid artery (ICA) nor ophthalmic symptoms. CASE: An 82-year-old man had transient blindness in both eyes. After left carotid endarterectomy, ophthalmic symptoms improved in the right and left eyes. Afterwards, he had a relapse in the left eye. RESULTS: There was no unusual impression in the ophthalmic examinations, but color Doppler imaging showed reduced flow in the left OA, reversal of flow direction in the right OA. The central retinal artery (CRA) and short posterior ciliary arteries (SPCA) were not detected in the left eye but were detected in the right eye. Digital subtraction angiography demonstrated that the right OA was not contrasted with the right ICA, despite there being no stenosis or occlusion of the right ICA. CONCLUSIONS: We suggest that carotid surgery may affect the ocular circulation of the opposite side, and reversed OA flow as a collateral pathway from the external carotid artery may occur in the absence of carotid artery stenosis. Good circulation of the CRA and SPCA may preclude manifestation of ophthalmic symptoms even if the OA flow is reversed.

yam8(+), a Schizosaccharomyces pombe gene, is a potential homologue of the Saccharomyces cerevisiae MID1 gene encoding a stretch-activated Ca(2+)-permeable channel.

The Saccharomyces cerevisiae MID1 gene encodes a stretch-activated Ca(2+)-permeable channel. In a protein database, we found a Schizosaccharomyces pombe gene whose predicted protein shows 26% identical and 62% similar to the Mid1 channel in amino acid sequence. cDNA derived from this gene, designated yam8(+), was isolated by reverse transcription-polymerase chain reaction (RT-PCR). Further analysis showed that the Yam8 protein consists of 486 amino acids and has 6 hydrophobic segments. The yam8(+) cDNA, placed under the S. cerevisiae TDH3 promoter, partially complemented the mating pheromone-induced death (mid) phenotype of the S. cerevisiae mid1 mutant. The expression of the yam8(+) cDNA in the mid1 mutant cells partially remediated the mid phenotype and resulted in a slight increase in Ca(2+) uptake activity. These findings suggest that Yam8 is a potential homologue of Mid1.

Genetic engineering of the unsaturation of fatty acids in membrane lipids alters the tolerance of Synechocystis to salt stress.

The role of unsaturated fatty acids in membrane lipids in the tolerance of the photosynthetic machinery to salt stress was studied by comparing the desA-/desD- mutant of Synechocystis sp. PCC 6803, which contained monounsaturated fatty acids, with the wild-type strain, which contained a full complement of polyunsaturated fatty acids. In darkness, the loss of oxygen-evolving photosystem II activity in the presence of 0.5 M NaCl or 0.5 M LiCl was much more rapid in desA-/desD- cells than in wild-type cells. Oxygen-evolving activity that had been lost during incubation with 0.5 M NaCl in darkness returned when cells were transferred to conditions that allowed photosynthesis or respiration. Recovery was much greater in wild-type than in desA-/desD- cells, and it was prevented by lincomycin. Thus, the unsaturation of fatty acids is important in the tolerance of the photosynthetic machinery to salt stress. It appears also that the activity and synthesis of the Na+/H+ antiporter system might be suppressed under high-salt conditions and that this effect can be reversed, in part, by the unsaturation of fatty acids in membrane lipids.

[Use of sulfonylurea (SU) in the treatment of diabetes mellitus].

The main action of SU in the treatment of diabetes mellitus is the stimulation of insulin secretion, and the extrapancreatic action including stimulation of insulin actions in glycogen synthesis and inhibition of glucose production in liver is also reported. The indication of SU in the treatment of diabetes mellitus is for NIDDM usually after diet therapy or suitable exercise therapy. In IDDM and several special cases including diabetic ketoacidosis, severe infection, pregnancy, poor-controlled NIDDM, gangrane, surgery operation, severe renal or hepatic failure et al. insulin therapy should be started. In mild NIDDM, gliclazide, tolbutamide or acetohexamide is used, and in more severe NIDDM glibenclamide is used. The action time of chlorpropamide is very long, usually from 20 to 60 hours, therefore special care should be taken for hypoglycemia. As the causes for secondary failure, transition from NIDDM to IDDM, failure of diet therapy, glucose toxity and others are considered.

Surgical treatments for orthopaedic complications in long-term haemodialysis patients--a review of 546 cases over the last 8 years.

We reviewed 546 operative cases in haemodialysis patients during the past 8 years between June 1990 and May 1998. The average age of the 257 male and the 289 female patients was 57.1 years. The average period of haemodialysis was 14 years and 4 months. We discussed the etiology, pathological focus, frequency, symptoms, problems and operative indications. Carpal tunnel syndrome occurred most frequently, occupying 289 cases. Short-term postoperative results were positive in the initial case within 6 months after the occurrence of the first symptoms. Because no effective method preventing recurrence existed, synovectomy was used as much as possible in the initial operation. Surgical treatment was used for amyloid arthropathy in 15 shoulders. It was effective in cases resistant to any conservative treatment. For the knee joint, the arthroscopic synovectomy was performed in 8 cases, and total knee replacement in 6 cases. The results of the total knee replacement cases were good. However, recurrences were observed in 40% of the synovectomy cases. In the hip joint, the curettage and bone grafting were performed in 7 hips of 6 patients. All bone grafts were consolidated and there was no case of postoperative pathological fracture. In some cases with destructive spondyloarthropathy, the vertebrae involved spontaneously fused without severe kyphotic deformity. A case with mild pain and without neurological deficit can be treated conservatively. A case with severe pain, instability, and myelopathy indicates operative measures must be taken. Attention must be paid for a possible collapse of the grafted bone after the cervical level two anterior fusion. Haemodialysis patients are vulnerable to infection. This diagnosis is difficult to distinguish due to the weakened state of the immune system. Rigorous attention is required to prevent and detect infection in cases using artificial joints or instrumentation. The treatment of bone and joint disturbances from dialysis-related amyloidosis has become surgical due to the advancement of dialysis control. However, it remains one of the more conservative treatments. Determining the cause and establishing a method of treatment are desired as early as possible.

Characterization of delta 9 acyl-lipid desaturase homologues from Arabidopsis thaliana.

Two cDNAs, ADS1 and ADS2, were isolated from Arabidopsis. These cDNAs encoded proteins homologous to delta 9 acyl-lipid desaturases of cyanobacteria and acyl-CoA desaturases of yeast and mammals. The expression of ADS1 and ADS2 was organ-dependent. Cold temperature up-regulated the ADS2 expression, whereas it down-regulated the ADS1 expression.

Glycerol-3-phosphate acyltransferase in plants.

Glycerol-3-phosphate acyltransferase (GPAT) catalyzes the transfer of an acyl group from an acyl donor to the sn-1 position of glycerol 3-phosphate. The plant cell contains three types of GPAT, which are located in the chloroplasts, mitochondria and cytoplasm, respectively. The enzyme in chloroplasts is soluble and uses acyl-(acyl-carrier protein) as the acyl donor, whereas the enzymes in the mitochondria and the cytoplasm are bound to membranes and use acyl-CoA as the acyl donor. cDNAs for GPAT of chloroplasts have been cloned from several plants, and the gene for the enzyme has been cloned from Arabidopsis thaliana. The amino acid sequences deduced from the nucleotide sequences of cDNAs indicate that the product of translation is a precursor of about 460 amino acid residues, which consists of a leader sequence of about 70 amino acid residues and a mature protein of about 400 residues, with a molecular mass of about 42 kDa. Genetic engineering of the unsaturation of fatty acids has been achieved by manipulation of the cDNA for the GPAT found in chloroplasts and has allowed modification of the ability of tobacco to tolerate chilling temperatures.

Membrane lipid unsaturation modulates processing of the photosystem II reaction-center protein D1 at low temperatures.

The role of membrane lipid unsaturation in the restoration of photosystem II (PSII) function and in the synthesis of the D1 protein at different temperatures after photoinhibition was studied in wild-type cells and a mutant of Synechocystis sp. PCC 6803 with genetically inactivated desaturase genes. We show that posttranslational carboxyl-terminal processing of the precursor form of the D1 protein is an extremely sensitive reaction in the PSII repair cycle and is readily affected by low temperatures. Furthermore, the threshold temperature at which perturbations in D1-protein processing start to emerge is specifically dependent on the extent of thylakoid membrane lipid unsaturation, as indicated by comparison of wild-type cells with the mutant defective in desaturation of 18:1 fatty acids of thylakoid membranes. When the temperature was decreased from 33 degrees C (growth temperature) to 18 degrees C, the inability of the fatty acid mutant to recover from photoinhibition was accompanied by a failure to process the newly synthesized D1 protein, which accumulated in considerable amounts as an unprocessed precursor D1 protein. Precursor D1 integrated into PSII monomer and dimer complexes even at low temperatures, but no activation of oxygen evolution occurred in these complexes in mutant cells defective in fatty acid unsaturation.

Human plasma leptin in obese subjects and diabetics.

Leptin is the protein product of the ob gene, an adipocyte-specific gene, recently discovered in mice. Plasma leptin levels were determined in six normals, twenty-one subjects with impaired glucose tolerance, and forty-nine untreated NIDDM subjects. They increased with the augmentation of obesity (body mass index, BMI kg/m2) and were higher in females than in males: in BMI less than 25 kg/m2 the values of plasma leptin were 2.24 +/- 0.25 ng/ml (n=29) in males and 3.01 +/- 0.39 ng/ml (n=13) in females (P<0.054), respectively, in BMI between 25 kg/m2 and 30 kg/m2 they were 3.14 +/- 0.31 ng/ml (n=10) in males and 10.66 +/- 2.86 ng/ml (n=7) in females (P<0.0018) and in BMI higher than 30 kg/m2 their levels were 8.98 +/- 1.5 ng/ml (n=11) and 11.74 +/- 2.2 ng/ml (n=6) (P<0.23), respectively. The severity of diabetes mellitus judged from the fasting plasma glucose level had no influence on the plasma leptin levels during OGTT, but the leptin levels decreased significantly during a tolerance test (P<0.001), and similar results were also seen during a breakfast test. The fasting plasma leptin in the male with FBS less than 140 mg/dl had a significant correlation with the fasting plasma IRI level, but this correlation disappeared after taking obesity into consideration. Thus the plasma leptin was chiefly dependent on the body weight and gender and had no special relation to diabetic severity.

Targeted mutagenesis of acyl-lipid desaturases in Synechocystis: evidence for the important roles of polyunsaturated membrane lipids in growth, respiration and photosynthesis.

Acyl-lipid desaturases introduce double bonds (unsaturated bonds) at specifically defined positions in fatty acids that are esterified to the glycerol backbone of membrane glycerolipids. The desA, desB and desD genes of Synechocystis sp. PCC 6803 encode acyl-lipid desaturases that introduce double bonds at the delta12, omega3 and delta6 positions of C18 fatty acids respectively. The mutation of each of these genes by insertion of an antibiotic resistance gene cartridge completely eliminated the corresponding desaturation reaction. This system allowed us to manipulate the number of unsaturated bonds in membrane glycerolipids in this organism in a step-wise manner. Comparisons of the variously mutated cells revealed that the replacement of all polyunsaturated fatty acids by a monounsaturated fatty acid suppressed growth of the cells at low temperature and, moreover, it decreased the tolerance of the cells to photoinhibition of photosynthesis at low temperature by suppressing recovery of the photosystem II protein complex from photoinhibitory damage. However, the replacement of tri- and tetraunsaturated fatty acids by a diunsaturated fatty acid did not have such effects. These findings indicate that polyunsaturated fatty acids are important in protecting the photosynthetic machinery from photoinhibition at low temperatures.

Effects of aminoguanidine on glucagon and insulin release from rat pancreatic islet.

Aminoguanidine (AG) is a potential therapeutic agent for preventing the generation of advanced glycation end products in diabetes mellitus. In this study, the effects of AG on glucagon and insulin secretion in in vitro rat pancreatic islets were investigated. The islets were aseptically isolated and cultured in tissue culture medium 199 for 48 h with or without 9.1 mM AG (1 mg/ml). After the culture, 50 islets were perifused in Krebs-Ringer bicarbonate buffer containing 20 mM arginine or 1 U/ml pancreozymin in the presence of 3.3 mM glucose. Islets previous exposed to AG showed similar glucagon response to control islets at a 20 mM arginine concentration, and insulin response, too. Glucagon release caused by 1 U/ml pancreozymin from the islets previously exposed to AG was also not different from that of the control islets, but the release of insulin was much lower than that of control. These results suggest that AG would not be toxic to alpha-cells but toxic to beta-cells at high concentrations, although there is slightly different sensitivity to beta-cell secretagogues.

Pancreatic amylin content in human diabetic subjects and its relation to diabetes.

To evaluate the pancreatic amylin in the pathogenesis of non-insulin-dependent diabetes mellitus (NIDDM), we determined the pancreatic amylin (IRA) and insulin (IRI) contents of pancreata obtained at autopsy from diabetics and nondiabetics. IRA was extracted from the tail of the pancreas using formic acid and assayed with a human amylin kit. Following gel filtration of amylin on a Sephadex G-50 column, it was eluted in a similar fraction to insulin. The pancreatic IRA content was significantly higher (p < 0.01) in NIDDM subjects compared with nondiabetics, with the mean values being 4.25 +/- 1.62 and 0.085 +/- 0.022 microgram/g, respectively. The IRA content of two IDDM pancreata was low. No significant relationship was found between the IRA and the IRI contents or between the IRA content and the duration of diabetes. However, there was a tendency for the IRA content to increase in longstanding diabetes. Men had a significantly higher pancreatic IRA content than women. The four subjects with very high IRA levels ( > 10 micrograms/g) were all elderly men with a long duration of diabetes. Thus, although the pancreatic amylin content was increased in NIDDM, no significant relationship to the clinical features of the disease was found.