Biomedical subjects

K Okamura

Publications and source records attributed to K Okamura.

At least 163 records · Page 9Linked to original sources

PubMed1996

An immunohistochemical study of HLA-DR and alpha 1-antichymotrypsin-positive cells in the pulp of human non-carious and carious teeth.

The condition of the pulp tissue was classified into seven groups according to the progression of carious lesions from stages S0 (non-carious teeth) to S6 (exposed pulp). There was a small number of anti-HLA-DR antibody-positive cells in the pulp of the early carious teeth, and a markedly increased number at S5 and S6. The recruitment of a large number of anti-HLA-DR cells concomitant with a marked increase of other kinds of immunocompetent cells in the pulp of late-stage caries might indicate the occurrence of antigen presentation followed by both cell-mediated and humoral immune reactions. The number of anti-alpha 1-antichymotrypsin (ACT) antibody-positive macrophages showed a proportional increase with the development of caries, and these cells may be involved in protecting against the tissue damage caused by proteases released from inflammatory cells, as well as having a defensive role by phagocytosis of toxic micro-organisms and damaged tissue residues. Thus anti-HLA-DR and anti-ACT antibody-positive cells might participate in both an efficient immune system and a tissue-protective mechanism in the human dental pulp.

Adult↗

PubMed1996

Immunological and chemical types of reversible hypothyroidism; clinical characteristics and long-term prognosis.

OBJECTIVE: Spontaneous improvement occurs in about one-half of patients with primary hypothyroidism who reside in an iodine-sufficient area of Japan, but the pathogenetic factors related to reversible hypothyroidism are still not fully understood. We therefore investigated the clinical features and prognosis of patients with reversible hypothyroidism with or without iodine excess and antithyroid antibodies. DESIGN: Amelioration of hypothyroidism was diagnosed when the elevated serum TSH concentrations (serum TSH concentration > or = 40 mU/l) decreased by 50% or more during an iodine restriction period of 2-15 weeks without replacement therapy. Reversible hypothyroidism occurred in a post-partum group (n = 20) and a non-post-partum group (n = 91). The latter was then further classified into chemical (n = 28), immunological (n = 20), and mixed (n = 43) groups, according to the presence of iodine excess (serum non-hormonal iodine level > 50 micrograms/l or a history of excess iodine ingestion), antithyroid autoantibody, or both, respectively. MEASUREMENTS: Clinical characteristics and long-term prognosis were compared among the four groups. The rate at which hypothyroidism recovered was expressed as the number of days required for a 50% decrease in the serum TSH concentration. The level of thyroid echogenicity was measured by 10-MHz ultrasonography. RESULTS: In the chemical group, the mean age, male:female ratio, and serum non-hormonal iodine concentrations were all higher than those in the immunological group. The estimated rate at which hypothyroidism recovered was rapid (6.1 +/- 3.1 (mean +/- SD) days), the levels of thyroid echogenicity were near normal, and a histological examination (n = 7) revealed either colloid goitre or a normal thyroid in the chemical group. In the immunological and post-partum groups, the recovery rate was slow (16.8 +/- 9.6 days and 16.2 +/- 5.8 days, respectively). The levels of thyroid echogenicity were markedly reduced but increased after the spontaneous recovery of the thyroid function in both groups. Aspiration cytology suggested lymphocytic infiltration in all patients examined in the immunological (n = 6) and post-partum groups (n = 4). Relapse to overt hypothyroidism was observed more frequently in the immunological (38%) and mixed groups (35%) than in the chemical group (5%). CONCLUSION: Thyroid damage was more severe, recovery slower and the rate of relapse higher in the immunological than in the chemical type of reversible hypothyroidism.

Adult↗

PubMed1996

Reversible primary hypothyroidism with blocking or stimulating type TSH binding inhibitor immunoglobulin following recombinant interferon-alpha therapy in patients with pre-existing thyroid disorders.

OBJECTIVE: Treatment with recombinant interferon-alpha (rIFN-alpha) may induce autoimmunity. We have evaluated the effect of rIFN-alpha on pre-existing thyroid disease with special reference to changes in TSH receptor antibody. DESIGN AND PATIENTS: Five patients, who had a history of autoimmune thyroid disease diagnosed between 2 and 16 years earlier (three patients had Graves' disease while two had Hashimoto's thyroiditis), were treated with rIFN-alpha for chronic hepatitis C. Before, during and after rIFN-alpha therapy, we determined thyroid function, antithyroid antibody, thyroid echogenicity and the surface phenotype of the peripheral and intrathyroidal lymphocytes. RESULTS: Four of the patients developed overt hypothyroidism after 4-7 months of rIFN-alpha therapy, and two of them had a preceding history of low-uptake thyrotoxicosis. Recovery of thyroid function was observed in all four patients. Strongly positive blocking type TSH receptor antibody was detected and an increase in the percentage of CD19 positive cells in the intrathyroidal lymphocytes was also observed in three of the patients even though the goitre size increased in two of them. One of the patients became thyrotoxic later when stimulating type TSH receptor antibody became positive. Another patient suffered from reversible hypothyroidism although stimulating type TSH receptor antibody remained strongly positive throughout the clinical course. CONCLUSIONS: Our data thus indicated a high incidence of an unusual type of reversible hypothyroidism with TSH receptor antibodies in patients with chronic hepatitis C and pre-existing autoimmune thyroid disease after recombinant interferon-alpha therapy through a mechanism involving both the humoral and cellular immune systems.

Adult↗

PubMed1996

Blood gas profiles of fetuses with abnormal Doppler flow in the umbilical artery.

This study was designed to show how accurately the pulsed Doppler fetal blood flow velocimetry reflects fetal blood gas values. Abnormal Doppler umbilical artery (UA) velocimetry was defined when the value deviated from the 95% confidence interval of the normal fetuses. Fetal acidemia, hypoxemia, or hypercapnia was defined when the fetal blood gas taken by funipuncture during pregnancy deviated from the 95% confidence interval of the standard. Positive predictive values of abnormal UA Doppler with acidemia, hypoxemia, and hypercapnia were 26.3, 29.2, and 25.4%, respectively. When an absence or reversal of diastolic flow was observed, positive predictive values of absence or reversal of UA Doppler were 71.4 for acidemia, 71.4 for hypercapnia, and 71.4 for hypoxemia. In conclusion, although it is difficult to presume the fetal blood gas profile by Doppler velocimetry alone, we have to recognize the deterioration of the fetal blood gas profile when we observe the absence or reversal in diastolic flow in the UA.

Blood Flow Velocity↗

PubMed1996

Difficulty in differentiating thyrotropin secreting pituitary microadenoma from pituitary-selective thyroid hormone resistance accompanied by pituitary incidentaloma.

A 33-year-old woman with inappropriate secretion of TSH and a 2-mm pituitary microadenoma is described. She had a high serum free T4 concentration (31 pmol/L) with an inappropriately nonsuppressible serum TSH concentration (0.93 mU/L). The alpha/TSH molar ratio was 2.3 and magnetic resonance imaging with gadolinium enhancement identified an area of low signal intensity in the left lateral pituitary gland. However, TSH secretion was not completely autonomous. There was a significant response to exogenous TRH stimulation and suppression by T3 administration. Therefore, it was difficult to rule out a nonfunctioning pituitary adenoma with concomitant pituitary selective thyroid hormone resistance syndrome. A 2-mm microadenoma was excised via transsphenoidal surgery. The tumor cells were immunoreactive to antisera to alpha-subunit and minimally immunoreactive to antisera to TSHbeta. The patient's thyroid function normalized after surgery without medication. Because the adenoma could become large and intractable if the patient was treated inadequately, early diagnosis and treatment are important in patients with TSH secreting adenomas.

Adenoma↗

PubMed1996

Ender nailing for unstable surgical neck fractures of the humerus in elderly patients.

The purpose of this study was to assess the effects of stabilization of displaced and unstable surgical neck fractures of the humerus by Ender nailing followed by protected passive range of motion exercise of the shoulder. Thirty-four patients (29 women and 5 men) with such fractures were treated. The average age of patients was 69.5 years (range, 48-86 years), and the average followup period was 9.9 months (range, 6-22 months). Protected passive range of motion of the shoulder was started in 2 weeks after surgery for 25 patients and in 3 to 4 weeks for 9 patients. All patients experienced pain relief immediately after surgery. Bone union occurred at 5.9 weeks (range, 4-10 weeks) in all but 1 patient. The average range of motion of the shoulder at followup was 129.7 degrees elevation and 43.2 degrees external rotation. The average limitation of elbow extension was 4.3 degrees. The most important points of this procedure are to obtain immediate relief of pain, to stabilize the unstable fragment, and to begin protected passive range of motion of the shoulder before extensive adhesions develop.

Aged↗

PubMed1996

Power spectral analysis for autonomic influences in heart rate and blood pressure variability in fetal lambs.

Variability of R-R intervals and arterial blood pressure signals in chronically instrumented fetal lambs was analyzed by power spectral analysis based on an assumption of maximum entropy. There were four consistent components, very low (VL, 0.01-0.025 cycle/beat), low (L, 0.025-0.125 cycle/beat), middle (M, 0.125-0.2 cycle/beat), and high (H, 0.2-0.5 cycle/beat), in the normal heart rate variability and blood pressure spectra. Integrated peaks in the power spectrum were compared before and after the administration of sympathetic and parasympathetic blockades. beta-Sympathetic blockade reduced the spectral power in the VL and L frequency components. alpha-Sympathetic blockade reduced only the M frequency component in the spectrum of R-R interval variability. Parasympathetic blockade reduced the H and L frequency components in the R-R interval variability spectrum but increased these components in the systolic blood pressure variability spectrum. The results clearly demonstrate the association between fetal autonomic activity and change of power spectrum of heart rate and blood pressure variability.

Animals↗

PubMed1996

Biological behavior of human dental pulp cells in response to carious stimuli analyzed by PCNA immunostaining and AgNOR staining.

The change in proliferative and metabolic activities of human dental pulp cells responding to carious stimuli was studied by means of immunohistochemical staining for proliferating cell nuclear antigen (PCNA) and silver-binding nucleolar organizer region (AgNOR) staining. We classified the pulp tissues into five groups according to the progression of dental caries, ranging from grade 0 (the pulp of noncarious teeth) to grade 4 (the pulp of perforated carious teeth). PCNA-positive pulp cells were detected only in advanced dental caries (grades 3 and 4), and the difference in immuno-positive rate was significant between the two grades (p <0.001). However, the mean number of AgNORs per nucleus increased even in the early phase of dental caries, significant differences being detected between grades 1 and 2 (p<0.005), 2 and 3 (p<0.005), and 3 and 4 (p<0.001). Our data suggested that the metabolic activity of dental pulp cells was enhanced in the early phase of dental caries. However, proliferation of pulp cells occurred later in small degrees during fully developed caries such as grades 3 and 4. The slow and weak response in cellular proliferation might contribute to the usual fragility of the pulp to various assaults including caries or pulpitis.

Adult↗

PubMed1996

Spectral analysis of beat-to-beat intervals of the fetal heart obtained by Doppler ultrasound.

Fetal heart rate monitoring has been widely used for the early investigation of the fetal outcome in current clinical settings. Interpretation of fetal heart rate tracing is sometimes indecisive, especially when the fetus is premature. In contrast to adults, the frequency analysis of fetal heart rate fluctuations has been unsuccessful. In this study, we succeeded in nonstationary frequency analysis of fetal heart rate fluctuations, using noninvasive Doppler ultrasound to measure beat-to-beat intervals of fetuses. We used an autoregressive method based on a 24-cycle stationarity. A dual peak was observed in the range of 0-0.125 cycles/beat from at least 20 weeks of gestation which increased in the resting state with gestational age. The peak area increased remarkably with fetal movement. The integrated value of the peak area will provide a powerful approach to the understanding of the development of fetal autonomic function and to a new fetal monitoring.

Electrocardiography↗

PubMed1996

Acute exacerbation of masked hyperthyroidism after iodine restriction followed by thyrotoxic atrial fibrillation and cerebral embolism. A case report.

The authors present a seventy-two-year-old woman complaining of diffuse and firm goiter. At the first visit, she looked almost euthyroid with regular pulse rate of 78 per minute. After iodine restriction, however, she became severely thyrotoxic and developed cerebral embolism associated with atrial fibrillation due to Graves' hyperthyroidism. In conclusion, sudden withdrawal of dietary iodine might lead to exacerbation of Graves' hyperthyroidism resulting in serious cardiovascular or cerebrovascular complications, especially in elderly patients.

Aged↗

PubMed1996

Risk factors for brain infarction in patients with Cushing's disease. Case reports.

Two women aged 51 and 52 years old, respectively, developed a brain infarction before and after undergoing treatment for Cushing's disease. A biochemical remission was obtained more than ten years after the onset of signs or symptoms of Cushing's disease. The arteriosclerotic changes of the cerebral vessels progressed even during replacement therapy for posttreatment hypopituitarism after they underwent either ablative surgery or radiotherapy. One patient, who showed the signs of Nelson's syndrome, demonstrated severe progressive cerebrovascular sclerotic changes, especially around the irradiated site. It is thus suggested that hypercortisolemia, external pituitary irradiation, and posttreatment hypopituitarism may be risk factors for brain infarction. The early diagnosis and adequate treatment are therefore important to prevent cerebrovascular complications in patients with Cushing's disease.

Cerebral Infarction↗

PubMed1996

Embolization for ruptured superior mesenteric artery aneurysms.

Superior mesenteric artery (SMA) aneurysms are very uncommon. They are difficult to detect until they rupture and cause hypovolaemic shock. We performed embolization in four cases of aneurysm of branches of the superior mesenteric artery, succeeding in three cases without the need for surgical treatment. In the first case, the aneurysm was excised because of migration of a microcoil into the left hepatic artery. It was not retrieved because sufficient blood flow to the liver was shown on angiography after migration and no ischaemic change of liver was detected on laparotomy. In the second case, the aneurysm arose from the anterior pancreaticoduodenal artery. In the third case, the patient had two SMA aneurysms; one had been resected at surgery, another was revealed on follow-up angiography and embolized with microcoils. The fourth patient had a jejunal artery aneurysm with extravasation; haemostasis was achieved by packing it. In all four cases, no major complications were observed in the clinical course after embolization. Microcoils were considered to be the desirable embolic material, in order to prevent post-therapeutic ischaemic change. Embolization should be the treatment of choice for SMA aneurysms, because it is less invasive and takes less time than surgical treatment.

Adult↗

PubMed1996

Cloning of stress tolerance gene in Torulaspora delbrueckii No. 3110.

A cryptic plasmid (pSRY1) was found in Torulaspora delbrueckii No. 3110. A plasmid vector (pSRY21) was constructed by ligating it to pPR1-RIM-C ORF with a cycloheximide resistance gene (RIM-C). The transformation efficiency of the strain No. 3110 with pSRY21 by the protoplast-PEG method was increased by 3000-fold by treatment of the protoplasts with polylysine [poly(epsilon-L-lysine)]. Previously we have reported a mutant No. 3110, T1, which can neither assimilate nor accumulate trehalose. The mutant was salt- and temperature-sensitive. We cloned a DNA fragment from No. 3110, which, when introduced, complemented these mutant characters of T1. These results suggested an important role of metabolism of trehalose for the stress tolerance.

Cloning, Molecular↗

PubMed1996

Scanning electron microscopy of fragmentary marker chromosomes observed by light microscopy.

To study the fine structure of fragmentary marker chromosomes, we performed scanning electron microscopy (SEM) on samples isolated from two carriers (Case 1: 46, XY/47, XY, +mar/48, XY, +mar, +mar; Case 2: 47, XY, +mar). In both cases, light microscopic observation revealed that marker chromosomes lacked a centromere and were fragmented in appearance. However, SEM observation of the metaphasic cells in both cases showed three variations. One variation was a structure that seemed to be metacentric, another was a structure that seemed to be submetacentric, and the remaining one was essentially fragmentary. However, neither the usual chromatid nor centromere formations were observed in the metacentric-like and submetacentric-like structures, even when both cases were observed by SEM. Moreover, the marker chromosomes of the boy of Case I, who suffered from various clinical troubles, included a greater population of metacentric-like or submetacentric-like structures than of essentially fragmentary structures. The marker chromosomes of the fetus of Case 2, who suffered from no clinical problems, included a much greater population of essentially fragmentary structures than metacentric-like or submetacentric like structures. Therefore, SEM observation of fragmentary marker chromosomes that are visible on light microscopy might be used to define specific structures. Moreover, SEM observation might provide clinical criteria relating to the pathogenesis of fragmentary marker chromosomes found on light microscopy.

Abnormalities, Multiple↗

PubMed1996

Hypopituitarism associated with transient diabetes insipidus followed by an episode of painless thyroiditis in a young man.

A 16-year-old male complained of a headache and a high fever followed by polyuria. The endocrinological studies showed he had hypopituitarism and central diabetes insipidus, and magnetic resonance imaging (MRI) revealed a pituitary mass. Diabetes insipidus gradually improved and hydrocortisone treatment was begun at three months after onset, but a month later painless thyroiditis developed. An MRI demonstrated a spontaneous shrinkage of the pituitary mass nine months after onset. Lymphocytic hypophysitis followed by painless thyroiditis was the most probable diagnosis, although it is very uncommon especially among men.

Adolescent↗

PubMed1996

Direct fermentative production of acyltylosins by genetically-engineered strains of Streptomyces fradiae.

A tylosin-producer, Streptomyces fradiae, was transformed with plasmids carrying genes from Streptomyces thermotolerans that are involved in acyl modification of macrolide antibiotics. A transformant with pMAB3, in which macrolide 4"-O-acyltransferase gene (acyB1) and its regulatory gene (acyB2) are subcloned, produced several types of 4"-O-acyltylosins. A transformant with pAB11 delta EH containing macrolide 3-O-acyltransferase gene (acyA) in addition to the above two genes produced 3-O-acetyltylosin and 3-O-acetyl-4"-O-acyltylosins. Among the products of the latter transformant, 3-O-acetyl-4"-O-isovaleryltylosin (AIV) was detected as a minor component. When L-leucine, a precursor of isovaleryl-CoA, was added to the medium at the late stage of the fermentation, AIV content among the total macrolides increased ten-fold and AIV became a main product. This fact suggests that a high level of endogenous isovaleryl-CoA may be essential for the selective production of AIV by S. fradiae carrying pAB11 delta EH.

Acylation↗

PubMed1996

Endoscopic trigonoplasty in pediatric patients with primary vesicoureteral reflux: preliminary report.

PURPOSE: We investigated the preliminary surgical results of endoscopic trigonoplasty in pediatric patients with primary vesicoureteral reflux. MATERIALS AND METHODS: We performed endoscopic trigonoplasty in 6 pediatric patients (11 refluxing ureters). Reflux was grade II in 4 reno-ureteral units, grade III in 5, grade IV in 1 and grade V in 1 (international classification). Surgery was done using laparoscopic and endoscopic instruments. RESULTS: Vesicoureteral reflux disappeared 3 to 12 months postoperatively. Analgesics were administered postoperatively to 4 patients for 24 hours and to 2 for 48 hours. No bladder irritability or postoperative upper urinary tract dilatation was observed in the early postoperative period. CONCLUSIONS: Minimally invasive endoscopic trigonoplasty can be an effective surgical procedure for pediatric patients with vesicoureteral reflux.

Child↗

PubMed1996

Hyaluronan, CD44 and fibronectin in rabbit corneal epithelial wound healing.

Changes in hyaluronan (HA) concentration and stainability were investigated in the rabbit cornea after wounds made by exposure to n-heptanol. The HA concentration in the cornea increased gradually until day 14 after wounding, and then decreased. The HA concentration returned to the normal level 56 days after wounding. In the normal control cornea, HA staining was observed in the epithelium and stroma. The intensity of HA staining in the epithelium and stroma increased until day 3 after wounding, when the epithelium had completely covered the defect. At day 28, when the thickness of the corneal epithelium returned to the normal level, the intensity of HA staining in the epithelium also decreased. However, staining in the stroma was still strong. HA staining in the stroma decreased by day 56 after wounding. In parallel experiments, the immunostaining for CD44, an HA receptor, and fibronectin (FN) was carried out in the same model. The immunostaining in the epithelium of both CD44 and FN was synchronistic with the HA staining during the early stages after wounding. These events suggest that HA, CD44 and FN cooperatively play important roles in corneal epithelial wound healing.

Alcohols↗