A Case of Acute-Onset Type 1 Diabetes Mellitus with Diabetic Ketoacidosis Triggered by COVID-19

BACKGROUND It is well known that diabetes mellitus contributes to COVID-19 severity. Recently, there have been reports of an increase in the number of children with type 1 diabetes after the COVID-19 pandemic. CASE REPORT A 52-year-old woman presented to the Emergency Department with disturbance of consciousness, accompanied by a 1-day history of thirst, a fever of 38°C, and breathlessness. She had a positive coronavirus antigen test. Her initial vital signs assessment showed a heart rate of 120 beats per minute, blood pressure 90/50 mmHg, temperature 37.3°C, and respiratory rate 30 breaths/minute with an oxygen saturation of 100% with 10 L oxygen inhalation. Her initial laboratory test results showed a blood glucose level of 1507 mg/dl, HbA1c of 10.1%, ketone 2+, and blood gas pH 7.113. The patient was diagnosed with diabetic ketoacidosis (DKA). There were mild inflammatory findings with blood CRP 0.14 mg/dl and a white cell count of 12 400/μL, but no pneumonia on a chest CT scan. Therefore, the patient was diagnosed with COVID-19 and DKA. The patient was positive for anti-glutamic acid decarboxylase (anti-GAD antibody) and had markedly low levels 24-h urine C-peptide (CPR). She was diagnosed with acute-onset type 1 diabetes mellitus, as her blood examination showed a postprandial blood glucose level of 100 mg/dl and HbA1c of 5.7% 2 months before admission. After admission, fluid replacement and continuous intravenous insulin infusion therapy were started, and blood glucose and blood gas pH improved over 10 h. CONCLUSIONS There have been reports of cases of type 1 diabetes consequences of COVID-19, but the mechanism has not been elucidated.

Multivariate Statistical and Multiproxy Constraints on Earthquake-Triggered Sediment Remobilization Processes in the Central Japan Trench

Understanding the impact of earthquakes on subaqueous environments is key for submarine paleoseismological investigations seeking to provide long-term records of past earthquakes. For this purpose, event deposits (e.g., turbidites) are, among others, identified and stratigraphically correlated over broad areas to test for synchronous occurrence of gravity flows. Hence, detailed spatiotemporal petrographic and geochemical fingerprints of such deposits are required to advance the knowledge about sediment source and the underlying remobilization processes induced by past earthquakes. In this study, we develop for the first time in paleoseismology a multivariate statistical approach using X-ray fluorescence core scanning, magnetic susceptibility, and wet bulk density data that allow to test, confirm, and enhance the previous visual and lithostratigraphic correlation across two isolated basins in the central Japan Trench. The statistical correlation is further confirmed by petrographic heavy grain analysis of the turbidites and additionally combined with our novel erosion model based on previously reported bulk organic carbon 14C dates. We find surficial sediment remobilization, a process whereby strong seismic shaking remobilizes the uppermost few centimeters of surficial slope sediment, to be a predominant remobilization process, which partly initiates deeper sediment remobilization downslope during strong earthquakes at the Japan Trench. These findings shed new light on source-to-sink transport processes in hadal trenches during earthquakes and help to assess the completeness of the turbidite paleoseismic record. Our results further suggest that shallow-buried tephra on the slope might significantly influence sediment remobilization and the geochemical and petrographic fingerprints of the resulting event deposits.

SAT-563 The Unsuppressed Plasma Renin Activity May Not Enough for Management of Non-Surgically Treated Primary Aldosteronism

It is well known the primary aldosteronism (PA) is most common endocrinological hypertension and accounted for 10% among all hypertension population, and it develops cardiovascular disease more frequently than blood pressure matched essential hypertension. Those patients with bilateral hyperaldosteronism, called idiopathic hyperaldosteronism (IHA), or unwilling for surgical treatment are treated by mineralcorticoid receptor antagonists (MRAs). Although it had been unclear how titrate MRAs to prevent atherosclerotic cardiovascular events, a managemental target for those patients was recently reported as plasma renin activity (PRA) ≥ 1.0 ng/ml/hr to prevent cardiovascular events (Hundemer GL, et. al. Lancet Diabetes Endocrinol. 2018 Jan;6(1):51-59).

Thus, we investigated 77 cases of adrenal venous sampling performed patients with PA and followed up for 3 years in our hospital since 2007, including 24 males and 53 females, and their mean age was 56.3 ± 12.5 years old. All patients underwent AVS and showed bilateral hyperaldosteronism and treated with MRAs and followed up more than 3 years. We collected blood pressure, serum sodium and potassium concentration, estimated glomerular filtration ratio (eGFR), PRA, plasma aldosterone concentration (PAC), atherosclerotic parameter, such as mean intima media thickness (IMT), brachial-ankle pulse wave velocity (baPWV) and ankle-brachial index (ABI). We evaluated the relationship of those patients’ PRA and aldosterone to renin ratio (ARR) with eGFR, IMT, baPWV, and ABI. The change of mean IMT after 3 year-follow up were 0.03 ± 0.11 mm vs. 0.06 ± 0.09 mm for well controlled (PRA ≥ 1.0 ng/ml/hr) and poorly controlled (PRA < 1.0 ng/ml/hr), respectively, and no significant difference between them. In the other hand, the change of mean IMT after 3 year-follow up showed 0.03 ± 0.10 mm vs. 0.08 ± 0.10 mm for well controlled (PRA ≥ 1.0 ng/ml/hr and ARR <20) and poorly controlled (PRA < 1.0 ng/ml/hr or ARR ≥ 20), respectively, and the mean IMT increase was significantly lower in this group.

The mean IMT increase showed significantly lower only with PRA ≥ 1.0 ng/ml/hr and ARR <20 rather than PRA ≥ 1.0 ng/ml/hr alone.

In our results, both PRA ≥ 1.0 ng/ml/hr and ARR<20 are important to prevent or improve atherosclerosis, rather than only PRA ≥ 1.0 ng/ml/hr and should be titrated MRAs to achieve this target.

In conclusion, our result revealed the titration of MRAs is important to prevent atherosclerotic cardiovascular event and not only PRA ≥ 1.0 ng/ml/hr, but both PRA and ARR <20 should be achieved.

Successful Treatment of Amiodarone-induced Thyrotoxicosis Type 1 in Combination with Methimazole and Potassium Iodide in a Patient with Hashimoto's Thyroiditis

A patient with underlying Hashimoto's thyroiditis developed amiodarone-induced thyrotoxicosis type 1 that was successfully treated using methimazole in combination with potassium iodide. A 35-year-old woman admitted for perinatal care of twin-to-twin transfusion syndrome was given amiodarone for 7 days for paroxysmal ventricular contraction following pulseless ventricular tachycardia 1 day after delivery. She developed thyrotoxicosis one month after the discontinuation of amiodarone therapy and was negative for thyroid-stimulating hormone receptor antibody. An increased peak velocity of the superior thyroid artery suggested amiodarone-induced thyrotoxicosis type 1. Her thyroid function recovered after combination therapy with methimazole and potassium iodide.

Sustained fasting glucose oxidation and postprandial lipid oxidation associated with reduced insulin dose in type 2 diabetes with sodium-glucose cotransporter 2 inhibitor: A randomized, open-label, prospective study

AIMS/INTRODUCTION

Hyperglycemia impairs energy substrate oxidation as a result of glucotoxicity. We examined whether the reduction of plasma glucose using a sodium-glucose cotransporter 2 inhibitor, in inpatient diabetes management, has any effect on: (i) treatment period and basal-bolus dosage of insulin that achieve euglycemia; (ii) fasting/postprandial energy expenditure (EE); and (iii) energy substrate oxidation.

MATERIALS AND METHODS

This was a randomized, open-label, 7-day prospective study. Participants were type 2 diabetes patients with hyperglycemia, aged >20 years, with glycated hemoglobin >10%, daily mean preprandial blood glucose >11 mmol/L (200 mg/dL) and no previous antidiabetic medication. A total of 18 type 2 diabetes patients were randomized (1:1) to basal-bolus insulin titration algorithm (INS) alone or INS + dapagliflozin 5 mg/day (INS/DAPA). The main outcome measures were total daily insulin dose to achieve euglycemia, as well as EE and respiratory quotient during fasting and postprandial states, measured by indirect calorimetry.

RESULTS

The rate of euglycemia was higher in the INS/DAPA compared with INS group (100 vs 55.6%, P = 0.04), whereas the total daily dose of insulin was 19% lower and was accompanied by a decreased basal-bolus ratio (P = 0.02). Fasting and postprandial EE elevation were similar in both groups. The post-treatment fasting respiratory quotient significantly increased in the INS/DAPA group (0.72 ± 0.05 vs 0.79 ± 0.08, P = 0.04), and the postprandial respiratory quotient elevation was abolished; the opposite trend was observed in the INS group (P < 0.02).

CONCLUSIONS

INS/DAPA sustained fasting carbohydrate oxidation, postprandial lipid-derived EE (failed to increase carbohydrate-derived EE) and reduced basal insulin requirement might be related to further bodyweight loss.

CLINICAL TRIAL REGISTRY

National University Hospital Medical Information Network UMIN000018997.

Efficacy of intermittent empagliflozin supplementation on dietary self-management and glycaemic control in patients with poorly controlled type 2 diabetes: A 24-week randomized controlled trial

AIMS

To explore the effects of intermittent use of empagliflozin, a sodium-glucose co-transporter-2 inhibitor, on dietary self-management and glycaemic control in patients with inadequately controlled type 2 diabetes.

MATERIALS AND METHODS

We conducted a prospective, randomized, open-label, blinded-endpoint, parallel-group, comparative clinical trial of 50 patients with type 2 diabetes, treated with no more than three oral antidiabetic drugs (glycated haemoglobin [HbA1c] ≥52 mmol/mol but <86 mmol/mol). The participants were randomized to take 10 mg/d empagliflozin either every day (regular group, n = 25) or on the day on which they considered they had overeaten (intermittent group, n = 25) for 24 weeks. We limited empagliflozin prescription to half of the required period in the intermittent group. The primary endpoint was change in HbA1c at the end of the 24-week treatment period relative to baseline. The secondary outcomes included changes in body weight, daily energy intake and diabetes treatment-related quality of life (QoL). Energy intake was assessed using a diet-specific validated questionnaire rather than actual assessments of food intake.

RESULTS

The intake rate of empagliflozin was 96.7 ± 7.2% for the regular group and 45.7 ± 7.0% for the intermittent group. Interestingly, ΔHbA1c was identical in the two groups (-0.64 ± 0.19% and - 0.65 ± 0.17%, respectively). Body weight decreased (-2.72 ± 0.52 and - 1.50 ± 0.45 kg, respectively) and diabetes treatment-related QoL increased significantly from baseline in both groups. Energy intake, however, decreased significantly only in the intermittent group (-221.0 ± 108.3 kcal/d).

CONCLUSIONS

Intermittent empagliflozin supplementation is a useful therapeutic option that empowers dietary self-management, improves glycaemic control and is accompanied by body weight loss and an increase in diabetes treatment-related QoL in patients with inadequately controlled type 2 diabetes.

Effectiveness of dapagliflozin on vascular endothelial function and glycemic control in patients with early-stage type 2 diabetes mellitus: DEFENCE study

Background

Recent studies reported that sodium glucose cotransporter 2 (SGLT2) inhibitors can potentially reduce the risk of cardiovascular mortality in patients with type 2 diabetes mellitus (T2DM). However, there is little or no information on the therapeutic effects of SGLT2 inhibitors on the progression of atherosclerosis. This dapagliflozin effectiveness on vascular endothelial function and glycemic control (DEFENCE) study was designed to determine the effects of dapagliflozin, a SGLT2 inhibitor, on endothelial function in patients with early-stage T2DM.

Methods

DEFENCE is a prospective, randomized, open-label, blinded-endpoint, parallel-group, comparative clinical trial. Between October 2015 and August 2016, 80 T2DM patients treated with 750 mg of metformin (hemoglobin A1c ≥6.0 and <8.0%, n = 80) were enrolled and randomized to receive either 1500 mg/day metformin (the metformin group, n = 40), or 750 mg/day metformin supplemented with 5 mg/day dapagliflozin (the dapagliflozin group, n = 40), for 16 weeks. The primary endpoint was a change in flow-mediated dilation (FMD) from baseline to the end of the 16-week treatment period. The secondary outcomes include changes in indexes of glycemic control, lipid metabolism, and oxidative stress, body composition, and safety evaluation.

Results

Although FMD tended to improve only in the dapagliflozin group, ΔFMD was comparable between the two groups. Analysis of patients with HbA1c >7.0% showed significant improvement of FMD in the dapagliflozin group than metformin group (P < 0.05). HbA1c, fasting plasma glucose, plasma glucagon, and body weight significantly decreased in both groups. Interestingly, urine 8-hydroxy-2′-deoxyguanosin, a biomarker of oxidative stress, was significantly lower in the dapagliflozin group than metformin group at 16 weeks (P < 0.001).

Conclusions

Dapagliflozin add-on therapy to metformin for 16 weeks improved endothelial function, as assessed by FMD, in patients with inadequately controlled early-stage T2DM. Improvement in oxidative stress may contribute to the improvement in FMD.

Trial registration University Hospital Medical Information Network Clinical Trial Registry (UMIN000018754)

Electronic supplementary material

The online version of this article (doi:10.1186/s12933-017-0564-0) contains supplementary material, which is available to authorized users.

Role of protein kinase C-angiotensin II pathway for extracellular matrix production in cultured human mesangial cells exposed to high glucose levels

The intrarenal renin-angiotensin system has been implicated in the pathogenesis of diabetic nephropathy. This study investigates the mechanisms for glucose-induced increase in angiotensin II (AII) production by human mesangial cells (MCs) in relation to protein kinase C (PKC). We also examine whether locally produced AII mediates extracellular matrix protein production in high-glucose conditions. Human MCs were cultured in 5 or 33 mmol/l glucose for 8 days, and were incubated with or without 5 mmol/l GFX, a PKC inhibitor, 0.1 micromol/l candesartan cilexetil (CC), a specific type 1 AII receptor antagonist, for another 24 h. In addition, MCs grown in 5 mmol/l glucose were incubated with 0.1 micromol/l phorbol-12,13-dibutyrate (PDBu) for 24 h. AII, TGF-beta1, fibronectin and type IV collagen in the culture media were measured by ELISA. The amount of AII secreted from MCs exposed to high-glucose levels was significantly greater (P<0.01) than that in normal glucose levels. The increase in AII production was completely prevented by GFX. The addition of PDBu mimicked the effect of glucose on AII production. The glucose-induced increases in the production of TGF-beta1, fibronectin and type IV collagen were partially, but significantly restored (P<0.01) by CC, while GFX totally abolished these effects of glucose. These results suggest that elevated glucose levels stimulate AII production via mechanisms dependent on glucose-induced PKC activation in human MCs, and that locally produced AII partly mediates the increase in mesangial matrix synthesis in high-glucose conditions.

Origins of gene, genetic code, protein and life: comprehensive view of life systems from a GNC-SNS primitive genetic code hypothesis

We have investigated the origin of genes, the genetic code, proteins and life using six indices (hydropathy, alpha-helix, beta-sheet and beta-turn formabilities, acidic amino acid content and basic amino acid content) necessary for appropriate three-dimensional structure formation of globular proteins. From the analysis of microbial genes, we have concluded that newly-born genes are products of nonstop frames (NSF) on antisense strands of microbial GC-rich genes [GC-NSF(a)] and from SNS repeating sequences [(SNS)n] similar to the GC-NSF(a) (S and N mean G or C and either of four bases, respectively). We have also proposed that the universal genetic code used by most organisms on the earth presently could be derived from a GNC-SNS primitive genetic code. We have further presented the [GADV]-protein world hypothesis of the origin of life as well as a hypothesis of protein production, suggesting that proteins were originally produced by random peptide formation of amino acids restricted in specific amino acid compositions termed as GNC-, SNS- and GC-NSF(a)-0th order structures of proteins. The [GADV]-protein world hypothesis is primarily derived from the GNC-primitive genetic code hypothesis. It is also expected that basic properties of extant genes and proteins could be revealed by considerations based on the scenario with four stages.

Transfer of heme oxygenase 1 cDNA by a replication-deficient adenovirus enhances interleukin 10 production from alveolar macrophages that attenuates lipopolysaccharide-induced acute lung injury in mice

By using a direct, intratracheal inoculation of an adenovirus encoding heme oxygenase 1 (Ad.HO-1), model gene therapy for acute lung injury induced by inhaled pathogen was performed. Data demonstrated that Ad.HO-1 administration is as effective as the pharmacologic upregulation of the endogenous HO-1 gene expression by hemin to attenuate neutrophilic inflammations of the lung after aerosolized lipopolysaccharide (LPS) exposure. Interestingly, immunohistochemical analysis revealed that the HO-1 gene was transferred not only to the airway epithelium, but to the alveolar macrophages (AMs). Moreover, overexpression of exogenous HO-1 in the macrophages provided a high level of endogenous interleukin 10 (IL-10) production from the macrophages, and additional experiments using IL-10 knockout mice demonstrated that the increase in IL-10 in the macrophages was critical for the resolution of neutrophilic migration in the lung after LPS exposure. These results suggest that AMs not only are barriers for efficient gene transfer to the respiratory epithelium, but also represent logical targets for Ad-mediated, direct, in vivo gene therapy strategies for inflammatory disorders in humans.

Longitudinal study of the mental health of caregivers caring for elderly patients with dementia: effect of institutional placement on mental health

One hundred and three family caregivers of relatives with dementia were longitudinally surveyed to examine the course of caregivers' mental health after the relatives had been placed in full-time care facilities. Mental health was assessed twice, with a 6-month interval, using the Japanese version of the 60-item General Health Questionnaire. The degree of social dysfunction was significantly reduced within 6 months after placement, while the other indicators of mental health (e.g. anxiety-insomnia, depression, somatic symptom and psychiatric morbidity) were not reduced within this term. However, anxiety-insomnia and psychiatric morbidity were significantly reduced more than 6 months after placement. Analyses by caregivers' lineal relations to the relatives indicated that only daughters-in-law showed a significant decrease in anxiety-insomnia and a marginal reduction in psychiatric morbidity. This study suggests that caregivers' social dysfunction was more greatly reduced than anxiety-insomnia and psychiatric morbidity within a relatively short term after placement, and that its effects on mental health might vary with the lineal relations.

[Pleural B cell lymphoma presenting as paraplegia]

A 54-year-old man felt pain on the right side of his chest. Two months later, paraplegia developed. A chest CT scan revealed a pleural effusion and a mass lesion along the right parietal pleura. The lesion extended directly into the adjacent part of the spinal canal and compressed the spinal cord. Cytologic examination of the pleural effusion revealed atypical lymphoid cells, and examination of a transcutaneous biopsy specimen showed monotonous atypical B lymphocytes. The diagnosis was pleural malignant lymphoma. Chemotherapy induced a partial remission, but 14 months after the first examination he died of central nervous system involvement. Pleural lymphoma can directly compress the spinal cord and cause paraplegia. Early diagnosis and therapy greatly affect the outcome in patients with spinal cord compression.

[Primary pulmonary lymphoma diagnosed from monoclonality of lymphocytes in a transbronchial biopsy specimen]

A 57-year-old man was found on a routine chest X-ray examination to have three infiltrative shadows: two in the right lung field and one in the left. Examination of a transbronchial biopsy specimen revealed infiltration of many small lymphocytes under the bronchial mucosa. In situ hybridization showed that they were monoclonal, and primary pulmonary lymphoma was diagnosed. The patient also had liver cirrhosis, diabetes mellitus, and hypertension. He was treated with a combination of pirarubein, cyclo-phosphamide, vindesine, prednisolone, and etoposide, but the tumors did not shrink. Therefore, as of the time of this writing he was being given only etoposide.

[Eosinophilic pneumonia presenting as a mass shadow]

A 35-year-old man underwent routine chest roentgenography and a mass shadow was seen in the left lung field. Examination of a transbronchial lung biopsy specimen revealed that many eosinophils had infiltrated under the bronchial mucosa and into the alveolar septum. The total serum IgE concentration was high, and skin tests with Aspergillus antigen and serum precipitating antibodies against Aspergillus were positive. The mass lesion disappeared without any therapy, and a cystic lesion remained. Mediators released from eosinophils were thought to have damaged the lung tissue. We should have administrated corticosteroids as soon as possible.

A possible origin of newly-born bacterial genes: significance of GC-rich nonstop frame on antisense strand

Base compositions were examined at every position in codons of more than 50 genes from taxonomically different bacteria and of the corresponding antisense sequences on the bacterial genes. We propose that the nonstop frame on antisense strand [NSF(a)] of GC-rich bacterial genes is the most promising sequence for newly-born genes. Reasons are: (i) NSF(a) frequently appears on the antisense strand of GC-rich bacterial genes; (ii) base compositions at three positions in the codon are nearly symmetrical between the gene having around 55% GC content and the corresponding NSF(a); (iii) amino acid compositions of actual proteins are also similar to those of hypothetical proteins from the GC-rich NSF(a); and (iv) proteins from NSF(a) of 60% or more GC content are flexible enough to adapt to various molecules encountered as novel substrates, due to the high glycine content. To support our proposition, using a computer we generated hypothetical antisense sequences with the same base compositions as of NSF(a) at each base position in the codon, and examined properties of resulting proteins encoded by the imaginary genes. It was confirmed that NSF(a) of GC-rich gene carrying about 60% GC content is competent enough for a newly-born gene.

[A case of cervico-mediastinal tuberculous lymphadenitis]

A 27-year-old female presented to our hospital because of anterior chest pain and left cervical tumor. Her chest X-ray film showed bilateral swelling of the superior mediastinum, which was composed of multiple mediastinal masses with obliteration of adjacent mediastinal fat on chest CT film. A specimen obtained from a left cervical lymph node histologically showed granuloma formation with central caseous necrosis, and the diagnosis of cervicomediastinal tuberculous lymphadenitis was therefore made. Both cervical tumor and mediastinal masses decreased in size following antituberculous chemotherapy. Mediastinal tuberculous lymphadenitis in young adults is rare. It is difficult to differentiate this condition from other mediastinal tumors, although its CT findings are characteristic.

Guanylate kinase of Escherichia coli K-12

We have identified the gene gmk, in the same operon as rpoZ, spoT, and recG at about 82 minutes on the Escherichia coli chromosome. The gmk (GMP kinase) gene encodes a peptide of 23,592 Da, possessing extensive similarity to the amino acid sequence of guanylate kinase from yeast. To confirm that gmk truly encodes guanylate kinase and to explore some of its enzymatic features, we have overproduced the product of gmk and purified it to homogeneity. Unlike guanylate kinases purified from eukaryotic sources, E. coli guanylate kinase is multimeric, and ionic conditions dictate its protomeric state; under low ionic conditions it appears to be a tetramer while under high ionic conditions it is a dimer. Kinetic analysis reveals that guanylate kinase, again, unlike eukaryotic guanylate kinases, binds GMP cooperatively and that the observed cooperatively changes with ionic strength. These results indicate that, despite extensive sequence similarity to its eukaryotic counterparts, E. coli guanylate kinase is structurally and enzymatically different.

Unusually biased nucleotide sequences on sense strands of Flavobacterium sp. genes produce nonstop frames on the corresponding antisense strands

From investigation of eight Flavobacterium sp. genes encoding enzyme proteins, it was found that six genes had nonstop frames (NSFs) on the antisense strands, and base sequences of the genes are mainly composed of repeating triplet sequence(s), 5'-GNC-3' (where G and C are guanine and cytosine, and N is either of the four bases), in the reading frames. Thus, we concluded that the biased nucleotide sequences on the sense strands produce NSFs on the corresponding antisense strands. Furthermore, from the precise alignments of both nucleotide and amino acid sequences of two related Flavobacterium sp. genes, nyIB and nyIB', it was found that base replacements might have occurred symmetrically in the codons. That is, transversions between G and C were observed at high frequencies at the first and third positions of codons, but not at the second positions. At the first position, AG base transitions were observed much more than similar CT transitions, whereas CT transitions were found at the third positions at a relatively high frequency. These suggest that symmetrical base replacements in codons might be the main contribution to evolution in Flavobacterium sp. genes.

Residual guanosine 3',5'-bispyrophosphate synthetic activity of relA null mutants can be eliminated by spoT null mutations

It was known previously that 1) the relA gene of Escherichia coli encodes an enzyme capable of guanosine 3',5'-bispyrophosphate (ppGpp) synthesis, 2) an uncharacterized source of ppGpp synthesis exists in relA null strains, and 3) cellular degradation of ppGpp is mainly due to a manganese-dependent ppGpp 3'-pyrophosphohydrolase encoded by the spoT gene. Here, the effects of spoT gene insertions and deletions are compared with analogous alterations in neighboring genes in the spo operon and found to be lethal in relA+ strains as well as slower growing in relAl backgrounds than delta relA hosts. Cells with null alleles in both the relA and spoT genes are found no longer to accumulate ppGpp after glucose exhaustion or after chelation of manganese ions by picolinic acid addition; the inability to form ppGpp is reversed by a minimal spoT gene on a multicopy plasmid. Strains apparently lacking ppGpp show a complex phenotype including auxotrophy for several amino acids and morphological alterations. We propose that the SpoT protein can either catalyze or control the alternative pathway of ppGpp synthesis in addition to its known role as a (p)ppGpp 3'-pyrophosphohydrolase. We favor the possibility that the SpoT protein is a bifunctional enzyme capable of catalyzing either ppGpp synthesis or degradation.

Characterization of the spoT gene of Escherichia coli

The Escherichia coli spoT gene encodes a guanosine-3',5'-bispyrophosphate (ppGpp) 3'-pyrophosphohydrolase known to be responsible for cellular (ppGpp) degradation. The DNA sequence of the spoT region is presented. The spoT gene is deduced to be 702 codons long, with a probable UUG initiation codon, and a deduced mass of 79,342 daltons. Two spoT mutations (spoT202 and spoT203) have been localized to an open reading frame by complementation of function as well as by genetic marker rescue. The ability to overexpress the spoT gene is limited, but enough ppGppase activity can be made to reverse ppGpp accumulation during the stringent response to amino acid starvation. The spoT gene is located within a larger spo operon and is flanked by two smaller genes. The first gene in the operon encodes omega, a protein that copurifies with RNA polymerase (Gentry, D. R., and Burgess, R. R. (1986) Gene (Amst.) 48, 33-40). The spoT gene is the second gene in the operon; it is followed by a third open reading frame deduced to encode a protein with a mass of 25,343 daltons. Insertion of a kanamycin resistance gene in the omega gene reduces spoT gene expression as judged by lowered ppGppase activity, relA-dependent reduction of growth rate, and abolition of spoT mutant complementation activity. These effects are reversed by expression of the spoT gene, but not the omega gene, in trans. Transcription of the spo operon occurs in a clockwise direction on the E. coli chromosome and is probably directed by at least two promoters.

Induction of stringent response by streptomycin in Bacillus subtilis cells

A stringent response was induced in Bacillus subtilis vegetative cells by streptomycin. This was confirmed as follows: In B. subtilis stringent cells (BR16S), stable RNA synthesis was repressed, and pppGpp and ppGpp were transiently synthesized in the presence of required amino acids and streptomycin. However, these phenomena were not observed in the isogenic relaxed strain (BR16R) under the same conditions. On the other hand, tetracyclines did not induce the response, and, moreover, the stringent response to streptomycin upon pretreatment of the stringent cells with the antibiotics was released.

Accumulation of relA gene-independent ppGpp in Bacillus subtilis vegetative cells upon temperature shift-down

Both Bacillus subtilis BR16S (rel+) and BR16R (relA-) cells accumulated ppGpp after a temperature shift-down from 37 to 0 degree C. This indicates that a ppGpp accumulation system is present in B. subtilis vegetative cells, which is induced upon cold-shock treatment and is mediated by a relA gene-independent product.

Induction of Bacillus subtilis sporulation by decoyinine and the concomitant disappearance of ppGpp in vegetative cells

Sporulation of Bacillus subtilis, growing exponentially in the presence of rapidly metabolizable nutrients, was induced by addition of decoyinine (an antibiotic inhibitor of GMP synthesis), and intracellular amounts of ppGpp were determined after 2 M formic acid extraction by polyethyleneimine (PEI)-cellulose thin-layer chromatography. Consequently, it was found that the ppGpp in vegetative cells abruptly disappeared after the addition of decoyinine. This indicates that the disappearance of ppGpp is closely correlated to the initiation of B. subtilis sporulation.

Disappearance of guanosine 5'-diphosphate 3'-diphosphate in Bacillus subtilis vegetative cells upon carbon source deprivation

Bacillus subtilis was grown in a nutrient medium, mNSMP, and a synthetic medium, mS6(C), in which spore formation was initiated after vegetative growth and exhaustion of carbon source or glucose. The amounts of intracellular phosphorylated compounds were analyzed at intervals by 2 M formic acid extraction and polyethyleneimine (PEI)-cellulose thin-layer chromatography followed by autoradiography. A hyperphosphorylated nucleotide, guanosine 5'-diphosphate 3'-diphosphate (ppGpp), was accumulated in cells during vegetative growth in both mNSMP and mS6(C), and then the nucleotide was degraded upon initiation of sporulation in both cases. Furthermore, after the nucleotide had disappeared in cells cultivated in mS6(C) upon exhaustion of the carbon source, it could be reformed in the sporulating cells by addition of glucose to the medium. These results suggest that the ppGpp in vegetative cells may function in the regulation of B. subtilis sporulation.

Presence of guanosine 5'-diphosphate 3'-diphosphate in Bacillus subtilis vegetative cells

Extracts of Bacillus subtilis vegetative cells with 2 M formic acid contained a large amount of a hyperphosphorylated nucleotide ("spot 4" nucleotide). The compound always comigrated with authentic guanosine 5'-diphosphate 3'-diphosphate (ppGpp) on two-dimensional polyethyleneimine (PEI)-cellulose thin-layer chromatography performed with three different solvent systems. Furthermore, all dephosphorylated 32P-labeled derivatives from the "spot 4" nucleotide comigrated on a one-dimensional PEI-cellulose plate with those from authentic ppGpp present in the same reaction mixture, when the compounds were hydrolyzed with snake venom phosphodiesterase or alkali. The level of the "spot 4" nucleotide (ppGpp) in the cell extracts was 0.14 nmol P/A660, corresponding to about one-third of the guanosine 5'-triphosphate (GTP) level and about 10% of the adenosine 5'-triphosphate (ATP) level. These results indicate that a "magic spot" nucleotide, ppGpp, is present at a high level in B. subtilis cells vegetatively growing in mNSMP.

Properties of unprimed poly(A)-poly(U) synthesis by Caulobacter crescentus RNA polymerase

Some properties of unprimed poly(A)-poly(U) synthesis by DNA-dependent RNA polymerase from Caulobacter crescentus were examined. The reaction required ATP and UTP as substrates and manganese as a divalent cation. Rifampicin completely inhibited the reaction at a concentration of 1 micron/ml, and the enzyme catalyzed the polymer synthesis well regardless of the presence of GTP, CTP or both. The chain length of the poly(A)-poly(U) synthesized was about one hundred base pairs, as estimated from a sedimentation velocity and the molar ratio of [3H]AMP to [gamma-32P]ATP incorporated into the poly(A)-poly(U). The reaction was dependent on the square of the enzyme concentration and the enzyme dimers formed complexes with poly(A)-poly(U) during the reaction.

Isolation and chemcial properties of A-protein from filamentous phage Fd

A-Protein was isolated from a purified male-specific filamentous phage fd particle. A-Protein has a molecular weight of approximately 60,000 daltons, as estimated by polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate. The amino-terminal residue was glycine as determined by the dansylation technique. Amino acid analysis showed that histidine, arginine, and cysteine, which are not contained in B-protein, are present in A-protein.