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Biomedical subjects

S Mashimo

Publications and source records attributed to S Mashimo.

At least 19 recordsLinked to original sources
PubMed2000

Globule-coil transition of denatured globular protein investigated by a microwave dielectric technique.

A mechanism for the gel-glass transition of denatured globular protein has been explained from the viewpoint of the globule-coil transition with microwave dielectric measurements using a time domain reflectometry (TDR) method. Boiled egg white, which is an aqueous gel of egg white prepared by heat treatment at 100 degrees C, becomes a glass on drying. In the gel state, the relaxation processes corresponding to the orientation of bulk water and the micro-Brownian motion of peptide chains of denatured protein were observed around 10 GHz and 10 MHz, respectively. When the gel-glass transition occurred, the relaxation strength for bulk water decreased rapidly as evaporation and breaking of water structure occurred. Simultaneously, the relaxation strength for micro-Brownian motion increased abruptly, as the structure of globular protein varied from globule state to coiled state. It is considered that the protein molecule spreads out and takes up a coiled state by reductions of hydrophobic and hydrophilic interactions of the globular protein. These reductions occur through a decrease in the amount of water.

Animals↗
PubMed1999

Time domain reflectometry: measurement of free water in normal lung and pulmonary edema.

The free water content of lung tissue was investigated by dielectric spectroscopy in normal lungs and in pulmonary edema induced by oleic acid in rats. The dielectric relaxation in a frequency range of 10(7) to 10(10) Hz was measured with the time domain reflectometry method at 25 degreesC. Three dielectric relaxation processes were analyzed for the lung tissue. A high-frequency process around 10 GHz was attributed to the orientation of free water molecules based on the relaxation time [log tauh (in s) = -11.03]. The dielectric strength (Delta epsilon) of this high-frequency peak (Delta epsilonh) should reflect the amount of free water in the tissue. Because the measured Delta epsilonh depended on the air content of the lung samples, the value of Delta epsilonh was corrected for the air content of each sample as determined by the point-counting method in the area where the time domain reflectometry data were obtained. The lungs of rats that received an injection of oleic acid had a significantly increased free water content [(Delta epsilonh of lung/Delta epsilon of pure water) x density of pure water] compared with that in the normal lung (0.76 vs. 0.59 g/cm3). These results indicate that free water occupies approximately 60% of the total volume of normal lung tissue and that there is an increase in free water in pulmonary edema.

Animals↗
PubMed1997

In vivo dielectric analysis of free water content of biomaterials by time domain reflectometry.

A method of in vivo analysis of the free water content in living organisms by dielectric analysis in the time domain is described. Human skin is chosen as an example of living tissue. The cells suitable for the measurement of various layers of human skin and calculation procedures for the waveform reflected from the probe end are described. The approach was confirmed to be effective for the determination of the water content through measurement of the standard samples, keratin-water mixtures. This method was also applied to human skin in vivo. Water content data measured with a probe specially designed for surface layer analysis were sensitive to humidity around the subject. The formula expressing the relation between the electrical field character of the probe, the permittivity depth profile, and the measured permittivity was used to analyze the water content profile as a function of the depth from the skin surface. The use of several kinds of probes, differing in their electric field characteristics, permitted evaluation of the water content depth profile of human skin. This procedure is easy and applicable to any sample due to its simplicity. The measurement needs only a touch of the probe on a sample spot. It is therefore a promising method of physicochemical research on living organisms and biomaterials.

Body Water↗
PubMed1997

Histamine-induced cortisol secretion from bovine adrenocortical cells: co-incubated with bovine adrenal medullary cells.

Histamine at concentrations higher than 10(-9) M significantly elicited cortisol secretion from bovine adrenocortical (BAC) cells co-incubated with bovine adrenal medullary (BAM) cells, suggesting that BAM cells are responsible for histamine-induced cortisol secretion. Cortisol secretion from BAC cells co-incubated with BAM cells was also elicited by both an H1 agonist, 2-methylhistamine, and an H2 agonist, 4-methylhistamine. However, 4-methylhistamine was much less effective than 2-methylhistamine. Histamine-induced cortisol secretion was inhibited not only by H1 antagonists (pyrilamine and diphenhydramine) but also by H2 antagonists (cimetidine and ranitidine). Histamine effectively increased 45Ca uptake and IP3 production in BAM cells. These responses were antagonized by the H1 antagonist but not by the H2 antagonist. Histamine-induced cortisol secretion from BAC cells co-incubated with BAM cells was inhibited by beta-adrenoceptor antagonists, propranolol and timolol, as well as an NK1-receptor antagonist, D-Arg1-D-Trp7,9-Leu11-substance P. These results indicate that histamine can induce cortisol secretion from BAC cells at physiological concentrations through H1 receptors on BAM cells, and catecholamine and substance P may participate in histamine-induced cortisol secretion.

Adrenal Cortex↗
PubMed1996

Dielectric properties of human fetal organ tissues at radio frequencies.

The in vitro dielectric properties of human fetal organ tissues were measured in the frequency range from 100 kHz to 500 MHz at 24 degrees C. The dielectric measurements were performed by using a network analyzer (HP4195A) and a coaxial line capacitive sensor. The tested samples, including skin, muscle, heart, lung, liver, kidney, spleen, and brain tissues, were obtained from the legal abortion of five women with 14-16 weeks gestation periods.

Abortion, Legal↗
PubMed1996

[A case of solitary metastasis from renal cell carcinoma to the thyroid gland].

A case of solitary metastasis with renal cell carcinoma to the thyroid gland is presented. The patient was a 54-year-old man found to have an abnormal mass in the neck. He had a past history of radical nephrectomy orignating from the right renal cell carcinoma 5 years earlier (pT2N0M0, G2 > 3, alveolar type, clear cell subtype). Ultrasonography revealed a tumor mass in the right hemithyroid gland. Right hemithyroidectomy was performed on April 19, 1995. Histopathologically, the removed thyroid tumor showed clear cell carcinoma. The possibility of a primary thyroid tumor was ruled out by immunohistochemical thyroglobulin staining, and the present case was thus diagnosed as of metastatic thyroid tumor of renal cell carcinoma. The present case is the 12th case of thyroid solitary metastasis of renal cell carcinoma reported in Japan to date.

Carcinoma, Renal Cell↗
PubMed1996

[Extracorporeal shock wave lithotripsy in an 8-month-old infant].

An 8-month-old boy who presented with pyrexia and vomiting was referred to the pediatric clinic of Kitasato University Hospital. He was found to have hematuria, proteinuria and pyuria. Abdominal X-ray film showed calcification suggesting renal staghorn calculus in the bilateral kidneys. At 10-months and 11-months, we succeeded in treating him with extracorporeal shock wave lithotripsy (ESWL) without complications.

Humans↗
PubMed1995

Dielectric study of the cooperative order-disorder transition in aqueous solutions of schizophyllan, a triple-helical polysaccharide.

Schizophyllan exists in aqueous solution as a triple helix, which is intact at room temperature. Its aqueous solution forms some ordered structure at low temperatures but undergoes a sharp transition to a disordered structure as the temperature is raised. The transition temperature Tc is about 7 and 18 degrees C for H2O and D2O solutions, respectively. This transition was followed by time-domain reflectometry to investigate dynamic aspects of the transition. In addition to a major peak around 10 GHz, the dielectric dispersion curve of a 20 wt % schizophyllan in D2O exhibited a small peak around 100 MHz below Tc and around 10 MHz above Tc. The major peak is due to bulk water, whereas the 100 MHz peak is assigned to "bound" or "structured" water, and that around 10 MHz to side-chain glucose residues. However, unlike usual bound water reported for biopolymer solutions, this "structured" water disappears abruptly when the temperature becomes close to Tc without accompanying a conformational transition of the main chain. The above assignment is consistent with the structure of the ordered phase derived from previous static data that it consists of side-chain glucose residues along with nearby water molecules surrounding the helix core that are interacting with each other loosely through hydrogen bonds, and spreads radially only a layer of one or two water molecules but a long distance along the helix axis.

Carbohydrate Conformation↗
PubMed1995

[Clinical experience with the artificial urinary sphincter AMS 800 for male incontinence].

BACKGROUND: The aim of this study is to evaluate the therapeutic efficacy of artificial urinary sphincter AMS 800 implants for male patients with urinary incontinence. METHODS: Eleven male patients with urinary incontinence were treated by implantation of the artificial urinary sphincter AMS 800 between 1988 and 1992. Patient age at the surgery ranged from 14 to 79 years, with a mean age of 58 years. At presentation, 9 patients (82%) had true incontinence and 2 had overflow incontinence, and medical treatments and/or surgical procedures (Teflon injections in 2 and Sling procedure in 1) had been attempted previously elsewhere in all patients. The etiologies of incontinence were post-prostatectomy (transurethral resection in 4 and radical retropubic prostatectomy in 4) in 8 patients (73%) and myelomeningocele, spinal cord injury, pelvic trauma in one each. There were 5 patients with abnormal cystometrogram, and 2 of them were performing intermittent self catheterization. Vesicoureteral reflux was determined in 2 patients preoperatively, which were surgically corrected one year before AMS800 implant in a patient and simultaneously in another patient. The cuff was placed around the bulbous urethra (9), pendulous urethra (1) or bladder neck (1). The device was activated 6 weeks post implantation, and the assessment of therapeutic effects was started 2 weeks after activation. RESULTS: Follow up ranged from 3 weeks to 75 months, with a mean of 56 months, if 3 cases done explantation due to periprosthetic infections were excluded. After AMS 800 implantation 5 patients (45%) were completely continent, 4(36%) required the use of not more than 1 pad per day, while a patient was not satisfied with the results and another patient was not definitive because of early explantation before device activation. Hence complete or near complete continence was achieved in 9 patients (81%). A patient is performing intermittent self catheterization in conjunction with the AMS 800 without any complications up until now. There were 3 periprosthetic infections (27%) associated with 2 cuff erosions, that consequently required explantation. Besides periprosthetic infection, neither complications nor mechanical device failures was experienced. CONCLUSION: In conclusion, the AMS 800 artificial urinary sphincter was safe with reasonable mechanical reliability and offered acceptable and satisfactory urinary control to the selected patients with incontinence.

Adolescent↗
PubMed1994

Emphysematous pyelonephritis, ureteritis, and cystitis in a diabetic patient.

This paper presents a case of gas-forming infection of the urinary tract in a diabetic patient. Plain film and computed tomography scans of the abdomen greatly facilitated clarification of the entire inflammatory process. The patient was cured by early nephrectomy conducted following unsuccessful treatment by percutaneous drainage.

Cystitis↗
PubMed1994

[Changes of plasma endothelin level in the early post-renal transplantation period].

Endothelin (ET) has been suggested to be involved in acute graft rejection of kidney transplantation and cyclosporin A (CsA) nephrotoxicity. For clarification of the pathophysiological role of ET in the early post-transplantation period, plasma endothelin-1 (ET-1) was measured by specific radioimmunoassay in renal transplant recipients, patients on maintenance hemodialysis (HD) and healthy volunteers. Twelve transplant recipients were used in this study, 8 of whom were living related subjects and 4 cadaver. Plasma ET-1 and graft function were measured each day, from 1 day prior and 7 days following transplantation and every week up to 5 weeks postoperatively. Plasma ET was measured in 20 other transplant recipients with stable function (serum creatinine < or = 1.8 mg/dl), 20 maintenance HD patients with no residual renal function and 6 healthy volunteers. Mean plasma ET-1 was 13.0 +/- 4.5 pg/ml in 20 recipients with stable graft function, 21.7 +/- 6.5 in 20 HD patients and 1.5 +/- 0.4 in healthy volunteers. These differences are statistically significant (p < 0.02). Plasma ET-1 showed significant decrease from 21.8 +/- 7.2 pg/ml prior to transplantation to 12.8 +/- 4.0 when urinary output reached more than 1000 ml in living and cadaveric transplantation subjects. All three acute vascular rejections clearly indicated histologically increased plasma ET-1 accompanied by an increase in serum creatinine. A significant positive liner correlation was noted between plasma ET-1 and serum creatinine during the first week following living transplantation. Two patients with clinically and histologically suspected CsA nephrotoxicity showed transient increase in plasma ET-1.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗