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Biomedical subjects

N Ikeda

Publications and source records attributed to N Ikeda.

At least 289 records · Page 16Linked to original sources

A scanning electron microscopy and electron probe X-ray microanalysis (SEM-EPMA) of pink teeth.

Samples of postmortem pink teeth were investigated by scanning electron microscopy and electron probe X-ray microanalysis. Fracture surfaces of the dentin in pink teeth were noticeably rough and revealed many more smaller dentinal tubules than those of the control white teeth. Electron probe X-ray microanalysis showed that the pink teeth contained iron which seemed to be derived from blood hemoglobin. The present study confirms that under the same circumstance red coloration of teeth may occur more easily in the teeth in which the dentin is less compact and contains more dentinal tubules.

Animals↗

An infant fatality involving ajmaline.

An infant fatality following accidental ingestion of ajmaline is described. Ajmaline was determined by thin-layer chromatography and infrared spectrophotometry, and quantitated by high performance liquid chromatography. The ajmaline concentration in blood was 5.5 micrograms/mL. The toxicological data relevant to the interpretation of case findings are presented.

Ajmaline↗

A fatal case of sulindac-induced Lyell syndrome (toxic epidermal necrolysis).

A 37-year-old woman died after 18 days from her starting to take sulindac for low back pain. Based on her clinical course and the autopsy findings, the cause of her death was Lyell syndrome (toxic epidermal necrolysis) induced by sulindac. This case is described together with the legal aspects of medical malpractice to which it gave rise.

Adult↗

Effects of flecainide on the cellular electrophysiology of neonatal and adult cardiac fibers.

The acute cellular electrophysiologic actions of flecainide acetate on isolated neonatal and adult canine ventricular myocardium and Purkinje fibers were evaluated with standard microelectrode techniques. Flecainide, 0.1 to 10.0 micrograms/ml, produced concentration-dependent decreases in action potential amplitude, overshoot, and phase O Vmax of adult ventricular myocardium and Purkinje fibers. The greatest effects were on Vmax. Neonatal action potential characteristics were affected to a lesser degree by flecainide. Flecainide had disparate effects on myocardial and Purkinje fiber repolarization and refractoriness. In adult ventricular myocardium, action potential duration (APD) and effective refractory period (ERP) increased progressively with drug concentration. APD and ERP were increased to a lesser degree in neonatal myocardium. In adult Purkinje fibers, APD decreased progressively with increasing flecainide concentrations. ERP decreased at 0.1 and 1.0 microgram/ml, but returned to control values at 10.0 micrograms/ml. APD and ERP of neonatal Purkinje fibers responded to a lesser degree. At faster stimulation frequencies (2 to 4 Hz), flecainide produced significant frequency-dependent decreases in Vmax in adult Purkinje fibers. Such use-dependency was not evident in neonatal fibers. These data indicate a significantly lower sensitivity of immature cardiac tissues to the electrophysiologic effects of flecainide.

Action Potentials↗

Molecular cloning and expression in Escherichia coli of a cDNA encoding human pancreatic elastase 2.

We have cloned a DNA that is complementary to the messenger RNA that encodes human pancreatic elastase 2 from a human pancreatic cDNA library using a cloned cDNA for rat pancreatic elastase 2 messenger RNA. This complementary DNA contains the entire protein coding region of 807 nucleotides which encodes preproelastase of 269 amino acids, and 4 and 82 nucleotides of the 5'- and 3'-untranslated sequences, respectively. When this deduced amino acid sequence was compared with known amino acid sequences it showed 82% homology with rat pancreatic elastase 2. This deduced sequence also contains a 16-amino-acid peptide identical with the N-terminal sequence determined for native human pancreatic proelastase 2. Taking the above findings together, we conclude that the cloned cDNA encodes a mature enzyme of 241 amino acids including 16 and 12 amino acids for a signal peptide and an activation peptide, respectively. Moreover, the predicted key amino acid residues involved in determining the substrate specificity of mammalian pancreatic elastase 2 are retained in the human enzyme. Cloned human pancreatic elastase 2 cDNA was expressed in E. coli as a mature and pro-form protein. Both resulting proteins showed immunoreactivity toward anti-elastase serum and enzymatic activity. We have also cloned and sequenced a porcine pancreatic elastase 2 cDNA.

Amino Acid Sequence↗

Pulmonary bone marrow embolic phenomena. Antemortem reactions in traumatic immediate death.

This study is based on an examination of lung tissue from 11 cases of traumatic immediate death with fracture. According to our investigation, pulmonary bone marrow embolic phenomena, such as megakaryocytes associated with fat globules in pulmonary arterioles and a megakaryocyte embolism in a pulmonary capillary, develop in most traumatic immediate death cases with fracture. From the results, we suggest that these pulmonary bone marrow embolic phenomena can be certain evidence of antemortem violence in traumatic immediate death cases.

Adult↗