Search PubMed⌕ Search

Biomedical subjects

K Doi

Publications and source records attributed to K Doi.

At least 145 records · Page 8Linked to original sources

Ethylnitrosourea (ENU)-induced apoptosis in the rat fetal tissues.

Ethylnitrosourea (ENU), a well known DNA alkylating agent, induces anomalies in the central nervous system (CNS), craniofacial tissues and male reproductive organs. In this study, pregnant rats were treated with 60 mg/kg ENU at day 13 of gestation, and their fetuses were examined from 1 to 48 hours after treatment (HAT) to find a clue for clarifying the mechanisms of the ENU fetotoxicity and teratogenicity. From 3 to 12 HAT, the moderate to marked increase in the number of pyknotic cells was detected in the fetal CNS, craniofacial mesenchymal tissues, gonads and so on. These pyknotic cells had nuclei positively stained by the TUNEL method, which is widely used for the detection of apoptotic nuclei, and they also showed electron microscopic characteristics identical to those of apoptotic cells. The present results strongly suggest that excess cell death by apoptosis in the fetal CNS, craniofacial tissues and gonads may have a close relation to the later occurrence of anomalies reported in these tissues following ENU-administration.

Alkylating Agents↗

Teratologic studies on rat perinates and offspring from dams treated with ethylnitrosourea (ENU).

Ethylnitrosourea (ENU), a well known DNA alkylating agent, induces anomalies in the central nervous system (CNS), craniofacial tissues, limbs and male reproductive organs. Recently we clarified that excess cell death caused by apoptosis occurred in these organs and tissues of rat fetuses from dams treated with ENU at day 13 of gestation (GD13). In this study, we examined fetuses at GD21 and offspring at 10 weeks of age after ENU administration to pregnant rats at GD13 in order to clarify the relationship between ENU-induced apoptosis in the fetal tissues and teratogenicity of ENU. Severe intrauterine growth retardation was observed in the ENU group, and the body weight of the offspring in the ENU group was significantly lower than that of the control group throughout the experiment. In addition, a high incidence of microencephaly, ectrodactyly and curved caudal vertebrae was observed in the offspring from dams treated with ENU at GD13. Judging from the results of our previous and present studies, it was strongly suggested that ENU-induced apoptosis in rat fetal tissues may play an important role in the induction of anomalies in the corresponding tissues.

Abnormalities, Drug-Induced↗

Aortic atheromatous lesions developed in APA hamsters with streptozotocin induced diabetes: a new animal model for diabetic atherosclerosis. 1. Histopathological studies.

To develop an adequate animal model for atherosclerosis in large vessels of patients with diabetes, i.e. diabetic macroangiopathy, we induced diabetes in APA hamsters with a single injection of streptozotocin (SZ) and examined the aorta histopathologically and immunohistochemically. As a result, hyperglycemia and hyperlipidemia were continuously observed for 26 weeks after the SZ injection (WAI) in APA hamsters. Fatty streaks characterized by a subendothelial accumulation of many foam cells were observed, limited to the aortic arches as early as 6 WAI. In addition to larger fatty streaks developing with the duration of diabetes, fibrous plaques and plaques containing calcium deposits or cholesterol clefts developed at 26 WAI. These lesions are generally similar to the atheromatous lesions developed in humans. Moreover, depositions of apolipoprotein E and advanced glycation end-products immunohistochemically detected in the lesions were very similar to those found in humans. The diabetic APA hamster is therefore considered to be a useful model for studying the formation of atheromatous lesions in diabetic patients.

Alloxan↗

Development of a digital image database for chest radiographs with and without a lung nodule: receiver operating characteristic analysis of radiologists' detection of pulmonary nodules.

OBJECTIVE: We developed a digital image database (www.macnet.or.jp/jsrt2/cdrom_nodules.html ) of 247 chest radiographs with and without a lung nodule. The aim of this study was to investigate the characteristics of image databases for potential use in various digital image research projects. Radiologists' detection of solitary pulmonary nodules included in the database was evaluated using a receiver operating characteristic (ROC) analysis. MATERIALS AND METHODS: One hundred and fifty-four conventional chest radiographs with a lung nodule and 93 radiographs without a nodule were selected from 14 medical centers and were digitized by a laser digitizer with a 2048 x 2048 matrix size (0.175-mm pixels) and a 12-bit gray scale. Lung nodule images were classified into five groups according to the degrees of subtlety shown. The observations of 20 participating radiologists were subjected to ROC analysis for detecting solitary pulmonary nodules. Experimental results (areas under the curve, Az) obtained from observer studies were used for characterization of five groups of lung nodules with different degrees of subtlety. RESULTS: ROC analysis showed that the database included a wide range of various nodules yielding Az values from 0.574 to 0.991 for the five categories of cases for different degrees of subtlety. CONCLUSION: This database can be useful for many purposes, including research, education, quality assurance, and other demonstrations.

Adult↗

Remnant-like particle cholesterol, triglycerides, and insulin resistance in nonobese Japanese type 2 diabetic patients.

OBJECTIVE: The aim of the study was to investigate the relationships between remnant-like particle (RLP) cholesterol, triglycerides, and insulin resistance in nonobese Japanese type 2 diabetic patients. RESEARCH DESIGN AND METHODS: A total of 86 nonobese Japanese type 2 diabetic patients (72 men and 14 women, aged 40-83 years, BMI 20.1-26.6 kg/m2) were studied. BMI, HbA1c levels, and fasting concentrations of plasma glucose, serum lipids (RLP cholesterol, total cholesterol, HDL cholesterol, and triglycerides), and serum insulin were measured. Insulin resistance was estimated by the homeostasis model assessment (HOMA-IR). The subjects were divided into two groups according to the value of HOMA-IR. Values >2.5 were indicative of the insulin-resistant state, and values <2.5 were indicative of the insulin-sensitive state. RESULTS: The insulin-resistant group had significantly higher RLP cholesterol and triglyceride levels and lower HDL cholesterol levels compared with the insulin-sensitive group. Univariate regression analysis showed that insulin resistance was positively correlated with BMI (r = 0.254, P = 0.019), HbA1c levels (r = 0.278, P = 0.011), RLP cholesterol levels (r = 0.315, P = 0.004), and triglyceride levels (r = 0.332, P = 0.002) and was negatively correlated with HDL cholesterol levels (r = -0.301, P = 0.006) in our diabetic patients. Multiple regression analysis showed that insulin resistance was independently associated with serum triglyceride levels, which explained 13.5% of the variability of insulin resistance in our nonobese Japanese type 2 diabetic patients. CONCLUSIONS: These results indicate that 1) nonobese Japanese type 2 diabetic patients with insulin resistance are characterized by high RLP cholesterol and triglyceride levels, and low HDL cholesterol levels; and 2) the level of serum triglycerides is an independent predictor of insulin resistance in these patients.

Apolipoproteins↗

[Endoscopic sinus surgery in flowing water].

A balloon has been developed that completely fills the choana, preventing water from leaking into the pharynx even when the water is entering into the nasal cavity at a rate of 1000 ml per minute. The balloon enables endoscopic sinus surgery (ESS) to be safely performed in "flowing water". This surgical technique is similar to that used in transurethral resections of the prostate because the tip of the endoscope is kept clean, and blood, debris and resected tissues are continuously removed by the water flow. In addition, the water pressure helps to suppress bleeding. This technique enables ESS to be performed with greater ease and efficiency. We have performed ESS in flowing water on 38 patients with chronic sinusitis under local anaesthesia. No complications, such as water leakage into the pharynx, were encountered, and only a few patients felt discomfort from the insertion of the balloon. Even if the balloon had burst, an emergency could have been easily prevented by withdrawing the endoscope from the nasal cavity and stopping the flow of water. Ultrasonography (USG) was used to examine the water-filled nasal cavity during surgery (SSD-2000 and Micro Tip Radial (ASU-101); Aloka, Ltd., Japan). Using USG, the middle turbinate, the inferior turbinate and the nasal septum could be visualized in a single coronal image. When the sensor was in the posterior ethmoid sinus, the orbit and its optic nerve could also be visualized. Since this surgery is performed under local anesthesia, eye movements can rapidly alter the position of the optic nerve. Thus, visualization of the optic nerve's exact position is extremely important. Unfortunately, USG is not very useful for localizing structures and guiding the surgeon to distant tumors or cysts located behind thick bones, since ultrasound can not penetrate hard masses or bones. In this situation, navigation systems are more reliable than USG. Nevertheless, USG is often useful for depicting surgical sites, especially during a crisis, if the medial wall of the orbit is thin or if the skull base has been broken, exposing the dura. USG can also provide early warning of an impending complication. USG also has several practical advantages over navigation systems: the cost of USG is much lower, preparation for surgery is unnecessary, visual information can be obtained in real time, and measurement accuracy (estimated to be about 2 mm for navigation systems) is not a consideration. Thus, USG can be easily used to avoid complications in most surgeries for chronic sinusitis. Flowing water also allows the nasal eavity to be completely washed and sterilized at the end of the surgery. This not only prevents post-operative infection, but enables sinus function to be more quickly recovered. In addition, the pressure from the balloon also prevents post-operative nasal hemorrhaging. This allows patients to be safely discharged from the hospital at an earlier time. The balloon can also be used for non-surgical purposes. For example, emergent epistaxis can be easily stopped by the insertion of this balloon, even if the doctor is not an otorhinolaryngologist. In addition, the balloon's soft pressure allows it to be left in the nose for long periods without any complications. We conclude that this simple balloon, which we have named the "Noda Balloon", is extremely useful for nasal treatments.

Adolescent↗

[Usefulness of temporal subtraction images of chest computed radiography for detection of metastatic pulmonary nodules].

Temporal subtraction is a technique by which a previous chest radiograph is subtracted from a current radiograph in order to enhance interval changes. Our purpose in this study was to evaluate the usefulness of temporal subtraction for the detection of metastatic pulmonary nodules. We examined 19 cases of metastatic nodules less than 15 mm in diameter (8.4 mm on average). Temporal subtraction images were created based on the matching of local lung areas in pairs of chest radiographs. By using the subtraction images, the detectability of nodules was clearly improved in 5 cases and moderately improved in 8 cases; there was no improvement in 6 cases. The subtraction images were especially useful for nodules superimposed over normal structures, such as rib, mediastinum, and diaphragm, as well as for small nodules. In 6 of the 19 cases, the nodules had been missed clinically; however, the temporal subtraction images clearly demonstrated half of missed small nodules. Temporal subtraction made it possible to enhance subtle interval changes and helped in detecting small pulmonary metastases. This technique seems promising for augmenting the capabilities of computed radiography of the chest.

Adult↗

Restoration of prehension with the double free muscle technique following complete avulsion of the brachial plexus. Indications and long-term results.

BACKGROUND: Recent interest in reconstruction of the upper limb following brachial plexus injuries has focused on the restoration of prehension following complete avulsion of the brachial plexus. METHODS: Double free muscle transfer was performed in patients who had complete avulsion of the brachial plexus. After initial exploration of the brachial plexus and (if possible) repair of the fifth cervical nerve root, the first free muscle, used to restore elbow flexion and finger extension, is transferred and reinnervated by the spinal accessory nerve. The second free muscle, transferred to restore finger flexion, is reinnervated by the fifth and sixth intercostal nerves. The motor branch of the triceps brachii is reinnervated by the third and fourth intercostal nerves to restore elbow extension. Hand sensibility is restored by suturing of the sensory rami of the intercostal nerves to the median nerve or the ulnar nerve component of the medial cord. Secondary reconstructive procedures, such as arthrodesis of the carpometacarpal joint of the thumb, shoulder arthrodesis, and tenolysis of the transferred muscle and the distal tendons, may be required to improve the functional outcome. RESULTS: The early results were evaluated in thirty-two patients who had had reconstruction with use of the double free muscle procedure. Twenty-six of these patients were followed for at least twenty-four months (mean duration, thirty-nine months) after the second free muscle transfer, and they were assessed with regard to the long-term outcome as well. Satisfactory (excellent or good) elbow flexion was restored in twenty-five (96 percent) of the twenty-six patients and satisfactory prehension (more than 30 degrees of total active motion of the fingers), in seventeen (65 percent). Fourteen patients (54 percent) could position the hand in space, negating simultaneous flexion of the elbow, while moving the fingers at least 30 degrees and could use the reconstructed hand for activities requiring the use of two hands, such as holding a bottle while opening a cap and lifting a heavy object. The results were analyzed to identify factors affecting the outcome. CONCLUSIONS: The double free muscle procedure can provide reliable and useful prehensile function for patients with complete avulsion of the brachial plexus.

Accessory Nerve↗

Evaluation of bone contusions with fat-saturated fast spin-echo proton-density magnetic resonance imaging.

OBJECTIVE: To evaluate the efficacy of fast spin-echo proton-density magnetic resonance imaging (MRI) with fat saturation sequences in the evaluation of bone contusions at the knee. METHODS: Analysis of 46 consecutive knee MRI examinations performed on patients referred from a sports medicine clinic after knee trauma. All examinations included coronal fast spin-echo proton-density fat saturation, fast spin-echo proton-density and fast spin-echo T2-weighted sequences. All 3 coronal sequences were blindly reviewed independently of each other by 3 experienced musculoskeletal radiologists to identify and grade bone contusions. RESULTS: Thirty-five bone contusions were identified in 24 patients. All bone contusions were identified on fast spin-echo proton-density fat saturation sequences, which was significantly greater than the percentage identified on either fast spin-echo T2-weighted sequences (21/35, 60%, p < 0.001) or fast spin-echo proton-density sequences (10/35, 29%, p < 0.001). Fourteen (40%) of the contusions were identified only on the fast spin-echo proton-density fat saturation sequences. The average grade of contusion for all 35 examinations was also significantly higher on the fast spin-echo proton-density fat saturation sequences than on the fast spin-echo proton-density and fast spin-echo T2-weighted sequences (p < 0.05). CONCLUSION: Fast spin-echo proton-density fat saturation sequences are more sensitive in the detection of bone contusions than fast spin-echo proton-density and fast spin-echo T2-weighted sequences. Assessment of other structures in the knee with fast spin-echo proton-density fat saturation MRI provides good spatial resolution and adequate T2-weighted information. It may have advantages over the more heavily T2-weighted fast spin-echo T2 fat saturation and inversion recovery sequences.

Adult↗