Biomedical subjects

I Suzuki

Publications and source records attributed to I Suzuki.

At least 145 records · Page 8Linked to original sources

PubMed1995

Identification and characterization of two nitrogen-regulated genes of the cyanobacterium Synechococcus sp. strain PCC7942 required for maximum efficiency of nitrogen assimilation.

Two nitrogen-regulated genes were found in the genomic DNA region upstream of the nirA operon involved in uptake and utilization of nitrate in Synechococcus sp. strain PCC7942. The two genes (nirB and ntcB) are transcribed divergently from nirA and encode proteins of 349 and 309 amino acid residues, respectively. The levels of nirB and ntcB transcripts were low in cells growing on ammonium and increased upon transfer of ammonium-grown cells to nitrate-containing medium. The deduced NirB protein sequence has no similarities to other known proteins, whereas the deduced NtcB protein sequence is homologous to bacterial transcriptional activators of the LysR family. Defined mutants constructed by interrupting nirB or ntcB with a drug resistance marker grew as fast as the wild-type strain on ammonium but grew slower than the wild-type strain on nitrate or nitrite. The nirB mutant had higher activities of nitrate reductase, glutamine synthetase, and glutamate synthase than the wild-type strain, but its nitrite reductase activity was 40% of the wild-type levels. The mutant excreted nitrite into the medium during growth on nitrate, showing that nitrite reductase limits nitrate assimilation. These findings suggested that nirB is required for expression of maximum nitrite reductase activity. When grown on ammonium, the nirB mutant grew normally but cultures of the ntcB mutant still showed a yellowish-green color typical of nitrogen-limited cells. NtcB seems to regulate utilization of fixed nitrogen by controlling the expression of a certain gene(s) involved in nitrogen metabolism.

Amino Acid Sequence↗

PubMed1995

A novel nitrite reductase gene from the cyanobacterium Plectonema boryanum.

The gene (nirA) for nitrite reductase was cloned from the nonheterocystous, filamentous cyanobacterium Plectonema boryanum. The predicted protein consists of 654 amino acids and has a calculated molecular weight of 72,135. The deduced amino acid sequence from positions 1 to 511 is strongly similar to the entire sequence of the ferredoxin-dependent nitrite reductases from other phototrophs, while the remainder of the protein is unique to the Plectonema nitrite reductase. The C-terminal portion of the protein (amino acids 584 to 654) is 30 to 35% identical to [2Fe-2S] ferredoxins from higher plants and cyanobacteria, with all of the four Cys residues involved in binding of the [2Fe-2S] cluster in the ferredoxins being conserved. Immunoblotting analysis of the extracts of P. boryanum cells showed that the NirA polypeptide has an apparent molecular mass of 75 kDa. An insertional mutant of nirA lacked the 75-kDa polypeptide, had no nitrite reductase activity, and failed to grow on nitrate and nitrite, indicating that the novel nirA is the sole nitrite reductase gene in P. boryanum and that the NirA polypeptide with the ferredoxin-like domain is the apoprotein of the functional nitrite reductase. As in Synechococcus sp. strain PCC7942, nirA is the first gene of a large transcription unit (> 7 kb in size) and is repressed by ammonium and derepressed simply by deprivation of ammonium from the medium. The development of nitrite reductase activity was, however, found to require the presence of nitrate in the medium.

Amino Acid Sequence↗

PubMed1995

En bloc petrosectomy using a Gigli saw for petroclival lesions. Technical note.

The authors report a new technique for en bloc petrosectomy using a Gigli saw as an alternative to drilling the petrous bone in the combined supra- and infratentorial approach or the transpetrosal-transtentorial approach. It is simple and easy and avoids postoperative cosmetic deformity. This technique has been performed in 11 petroclival lesions without injuring the semicircular canals, the cochlea, or the facial nerve.

Craniotomy↗

PubMed1995

Degradation of cystathionine gamma-lyase in rat liver lysosomes: effect of leupeptin treatment.

Highly purified lysosomes from the livers of normal and leupeptin-treated rats were subjected to immunoblot analysis, using antibodies against rat liver cystathionine gamma-lyase. Normal lysosomes showed small amount of single band at about 40 kDa, whereas the leupeptin-treated lysosomes showed large amounts of a major band at about 40 kDa and a minor band at about 35 kDa. These observations suggest that cystathionine gamma-lyase is sequestered into lysosomes at the original subunit molecular weight and is degraded in the lysosome by way of the sequential formation of an intermediate with distinct molecular weight.

Animals↗

PubMed1995

Changes in cystathionine gamma-lyase in various regions of rat brain during development.

Developmental changes in the activities of cystathionine beta-synthase and cystathionine gamma-lyase were measured in six regions of rat brain. On day-1, no differences were observed in the activities of cystathionine beta-synthase and cystathionine gamma-lyase among these regions, the values being about 40 nmol/h/mg protein, and 3 nmol/h/mg protein, respectively. Cystathionine beta-synthase activity increased gradually during development at almost the same rate in each region, reaching the adult level at week-4 (about 4-fold). Cystathionine gamma-lyase activity also increased during development, reaching adult level at week-2. But, the increase of enzyme activity in the cerebellum (about 1.8-fold) was clearly lower than that in the other regions (about 4-fold). Cystathionine gamma-lyase content in the various regions of week-3 rat brain estimated by immunoblotting was consistent with the enzyme activity, and the enzyme level in the cerebellum was lower than that in the other regions. Cystathionine content of cerebellum in week-3 increased rapidly during development, and was about five-fold more than that on day-1. However, cystathionine content in the other regions did not change during development. These findings indicated that at least one reason of the high content of cystathionine in the 3 weeks rat cerebellum was due to the low level of cystathionine gamma-lyase.

Animals↗

PubMed1995

[A benign clear cell tumor of the lung that grew gradually over five years].

A 38-year-old man was found to have an abnormal shadow in his chest X-ray film during a general medical examination. A nodule with a homogeneous density and a clear margin was seen in the upper lobe of the right lung. Since this shadow gradually enlarged during a five-year follow-up period, he was admitted to our hospital. Chest contrast and dynamic CT scans and aortography showed characteristics of a benign tumor with somewhat rich vascularity. The doubling time of this tumor was about 430 days. Transbronchial brushing for cytologic study and a transbronchial biopsy showed no malignancy. However, the tumor was surgically resected because of its gradual growth over the five years. The resected tumor was histologically diagnosed as a benign clear cell tumor of the lung. This disease was first described by Leibow and Castleman in 1963, as a benign pulmonary tumor similar to metastatic renal cell carcinoma. This disease is extremely rare and only 61 cases have been reported: twenty cases, including the present case, in Japan and 41 in other countries.

Adenocarcinoma, Clear Cell↗

PubMed1995

Pancreatic arteriovenous malformation involving adjacent duodenum in a patient with gastrointestinal bleeding.

Gastrointestinal bleeding caused by arteriovenous malformation (AVM) of the pancreas is extremely rare. A 56-yr-old man with AVM of the head of the pancreas who was presented with recurrent episode of melena is described herein. The preoperative diagnosis was confirmed by angiographic study, and he was successfully treated with pancreatoduodenectomy. Histological examination of the resected specimen revealed pancreatic AVM involving the adjacent duodenal wall.

Arteriovenous Malformations↗

PubMed1995

Evaluation of long-term results of Caroli's disease: 21 years' observation of a family with autosomal "dominant" inheritance, and review of the literature.

A 5-year-old girl underwent laparotomy in 1972 because of hepatomegaly and mottled radiopacities shown by cholangiography. Polycystic segmental dilatation of the intrahepatic bile ducts, typical of Caroli's disease, was found. Thereafter she remained in good health for over 21 years with careful medical management. In 1972 mottled radiopacities of the hepatic parenchyma were also demonstrated by cholangiography in her 9-year-old brother, who, however, remained asymptomatic until hematemesis due to esophageal varices suddenly occurred in 1993. At the time of the pre-operative evaluation for esophageal transection, his condition was definitively diagnosed as Caroli's disease. Their father was in good health, but in 1993 was shown by CT to have the same disease. The mode of inheritance is likely to be autosomal dominant, although Caroli's disease or congenital hepatic fibrosis is generally considered autosomal recessive (McKusick number 263200) (1). If we had not examined the father, this particular family would have been accepted as an example of autosomal recessive inheritance. We suggest that further family studies are needed to exclude the autosomal dominant mode of inheritance, and that at least some of the recessive cases in the literature are, in fact, autosomal dominant. Well-documented cases of "classical" Caroli's disease in the literature were reviewed with special reference to the long-term results. In addition, an international questionnaire aimed at establishing the further clinical course of the patient was sent to authors who reported cases after 1968.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1995

[Neural control of tracheal smooth muscle during cough].

Contraction of tracheal smooth muscle during mechanically induced coughing was studied in dogs. Recordings of smooth muscle tension were obtained from the cervical trachea, which is not influenced by intrathoracic pressure. We observed that during breathing at rest, tracheal smooth muscle contracts and relaxes in synchrony with phrenic nerve activity. When cough occurs, the tracheal smooth muscle contracts continuously and tonically with no rhythmic correlation to phrenic nerve activity. Sometimes the contraction starts before the phrenic nerve activity increases. A neuromuscular blocking agent caused a significant decrease in phrenic nerve activity in response to mechanical stimulation. The correlation between phrenic nerve activity and tracheal smooth muscle tension during normal breathing was also observed after afferent inputs from pulmonary mechanoreceptors were interrupted. During coughing, however, this correlation was lost. From these results we conclude that the neural control of tracheal smooth muscle is at least partially independent of phrenic nerve activity during coughing. Because coughing was attenuated by neuromuscular blocking agents, we speculate that there is a positive feedback mechanism from receptors in the chest wall or airway, which increases the magnitude of coughing.

Animals↗

PubMed1995

[Coronary artery-to-pulmonary artery fistula with aneurysm: two cases report].

We performed the operation for coronary artery-to-pulmonary artery fistula with aneurysm in two patients. The coronary angiograms of one patient, who was a 63-year-old female, revealed coronary artery-to-pulmonary artery fistula originated from the left coronary artery with 3 aneurysms of 2 cm in diameter, respectively. The angiogram of another patient, who was a 77-year-old female, revealed coronary artery-to-pulmonary artery fistula originated from both coronary arteries with the giant aneurysm of 7 cm in diameter. We decided to operate by the reason of possibility of rupture of the aneurysms, and performed resection of the fistulas and the aneurysms with the closure of the drainage openings into the pulmonary artery with the aid of cardiopulmonary bypass. It was recommended to resect the coronary aneurysm before growing big in the patient with the coronary artery-to-pulmonary artery fistula.

Aged↗

PubMed1995

[Fibronectin].

Explore the source record for details and available documents.

Adolescent↗

PubMed1994

Effect of vitamin B6 deficiency on the expression of glycogen phosphorylase mRNA in rat liver and skeletal muscle.

The effect of vitamin B6 deficiency on the expression of glycogen phosphorylase mRNA in rat liver and skeletal muscle was investigated. The level of phosphorylase mRNA in the muscle of vitamin B6-deficient rats was reduced to 40% of that in the control rats. By contrast, the phosphorylase mRNA level was increased 5-fold in the liver of the deficient animals. It was also found that the expression of the beta-actin gene, generally regarded as a 'housekeeping' gene, was unaffected by B6 deficiency in the muscle but was enhanced in the liver of the deficient animals. These observations suggest that vitamin B6 may modulate the transcriptional activation of the phosphorylase gene in a tissue-specific manner.

Actins↗

PubMed1994

Right atrial myxoma developing 4 years following patch closure of an atrial septal defect: report of a case.

We report herein the rare case of a 13-year-old boy in whom a right atrial myxoma developed 4 years following patch closure of an ostium secundum atrial septal defect, at which time no other atrial abnormality had been observed. The myxoma arose from the atrial septum in the area between the orifices of the coronary sinus and inferior vena cava. The suture line was not involved. Gross and histopathological findings were characteristic of atrial myxoma. Atrial myxomas are usually considered to be slow-growing neoplasms; however, this case demonstrates that the initial period of growth may be quite rapid in some cases.

Adolescent↗

PubMed1994

Induction of oral tolerance after feeding of ragweed pollen extract in mice.

The induction of oral tolerance following the feeding of ragweed pollen and its extract was investigated in BALB/c mice. Antibody class-specific immune suppression could be observed, and the IgE response was specifically suppressed, depending on the amount of ragweed pollen extract fed when subsequently immunized with ragweed extract together with A1(OH)3 as an adjuvant. A multiple feeding was more effective than a single feeding of antigen, and the IgE response was completely suppressed when 20 mg of pollen extract was fed for 5 consecutive days. On the other hand, IgG production was not suppressed even though a large amount of ragweed pollen or its extract was fed. Furthermore, no secretion of antigen-specific IgA into saliva was observed in control animals or those fed ragweed pollen extract. Thus, pollen extract feeding may be potentially useful for the prophylaxis or therapy of allergic rhinitis induced by ragweed.

Administration, Oral↗

PubMed1994

Risk factors for lung cancer in Rio de Janeiro, Brazil: a case-control study.

The association between the risk of lung cancer and tobacco smoking, dietary factors and occupational exposures was examined in a hospital-based case-control study. The study involved 123 consecutive cases and 123 controls, matched by age (+/- 3), sex, and race. In this first study of lung cancer risk in Brazil, we found that tobacco smoking is the strongest risk factor with an odds ratio (OR) for current and former smokers of 22 (CI, 6.5-76) and 7.7 (CI, 2.2-27), respectively. An OR of 2.8 (CI, 1.0-7.7) was found for users of black tobacco in the form of hand-rolled cigarettes) in combination with conventional cigarettes, after adjustment for life-time consumption of any kind of tobacco; users of conventional cigarettes only were considered as a reference group. Cessation of smoking had an important influence in reducing the lung cancer risk, whereas early initiation of smoking increased the risk. Among dietary factors, frequent consumption of meat (P < 0.01) and pasta (P = 0.02) were positively associated with lung cancer risk after adjusting for smoking and income. No association was found with green/yellow vegetables or fruits. We were unable to detect any significant association related to occupational exposures. This study confirmed the association of lung cancer with smoking as the most important predictor of risk. It also indicates the increase in risk associated with the use of black tobacco in combination with conventional cigarettes.

Adult↗

PubMed1994

Effect of pH on sulfite oxidation by Thiobacillus thiooxidans cells with sulfurous acid or sulfur dioxide as a possible substrate.

The oxidation of sulfite by Thiobacillus thiooxidans was studied at various pH values with changing concentrations of potassium sulfite. The optimal pH for sulfite oxidation by cells was a function of sulfite concentrations, rising with increasing substrate concentrations, while that by the cell extracts was unaffected. The sulfite oxidation by cells was inhibited at high sulfite concentrations, particularly at low pH values. The results from kinetic studies show that the fully protonated form of sulfite, sulfurous acid or sulfur dioxide, is the form which penetrates the cells for the oxidation.

Acidithiobacillus thiooxidans↗

PubMed1994

Diaphragmatic electrical activity during controlled and assisted mechanical ventilation in conscious human subjects.

Breathing during mechanical ventilation was analyzed in 8 conscious healthy volunteers by application of intermittent positive pressure ventilation through a mouthpiece. In controlled mechanical ventilation (CMV), the respiratory rate and tidal volume were fixed at 110 and 120% of the subject's corresponding spontaneous breathing parameters. The diaphragmatic electromyogram (EMGdi) decreased significantly but become synchronous with the rhythm of the CMV. In assisted mechanical ventilation (AMV), the EMGdi response developed prior to and during the inspiratory phase of AMV. Application of an unexpected mechanical breath elicited the EMGdi. As the triggering sensitivity was decreased, the EMGdi prior to and during a mechanical breath was augmented, however, its rate of rise was unaffected. Our results suggest that the EMGdi during mechanical ventilation in conscious subjects is initiated by the respiratory center, however, this activity is modulated strongly by input from the pulmonary afferents and from the cerebral cortex.

Cerebral Cortex↗

PubMed1994

[Surgical treatment of thrombosed aortic dissection].

We have performed the graft replacement of descending thoracic aorta for 6 patients with aortic dissection having non-opacified false channel on their initial CT and aortography from April 1990 to January 1993. We report the findings obtained from preoperative CT and aortographic findings and from operation with these patients. We also report the microscopic study of aortic wall resected at operation. In all the six patients were found by CT and angiography performed at the admission non-opacified false channel. In one patient, a re-dissection occurred at the mid-descending aorta four weeks later and extended into the abdominal aorta. Intimal tears were found during operation both at distal to the left subclavian artery and at mid-descending aorta in this patient, and microscopically the outer media of aortic wall had been ruptured and the advential scarring were more conspicuous than usual. In the other 5 patients, the local opacification was gradually increased in size during the follow up period. The site of local opacification was at the distal to the left subclavian artery in 3 and at the mid-descending aorta in 2. The operation for these patients revealed the existence of intimal tear at the involved aorta but the false channel had been closed. Microscopically, the involved aorta formed pseudoaneurysm and false channel had been closed with the organized thrombus. From these findings we conclude that surgical treatment should be considered for the aortic dissection when re-dissection occurred or local opacification was increased in size during follow up period, even if initial CT and aortography showed non-opacified false channel.

Aged↗