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Biomedical subjects

Y Kadota

Publications and source records attributed to Y Kadota.

At least 55 records · Page 3Linked to original sources
PubMed1993

Infraglottic aspect of canine vocal fold vibration: effect of increase of mean airflow rate and lengthening of vocal fold.

The mucosal upheaval (MU), where the mucosal wave starts and propagates upward, appears only when the vocal fold vibrates. The location of the MU histologically and the effect of changes in mean air flow rate (MFR) and vocal fold length on occurrence of the MU were studied in twelve excised canine larynges. The lower surface of the vocal fold was marked to serve as a landmark for subsequent study. Cricothyroid approximation was performed to lengthen the vocal fold. After taking high-speed pictures or recording stroboscopic images from the tracheal side, a small cut wound was made at the mark. This wound served to compare the position of the MU with the histologically identified location of the mark. The larynx was then sectioned in the frontal plane. Before lengthening the vocal fold, the MU occurred on the area where the lamina propria became thinner and where the muscular layer neared the epithelial layer. After lengthening the vocal fold, the MU actually shifted medially compared with its original position. The subglottic area surrounded by the bilateral MUs became longer and thinner. Whether or not complete glottal closure during a vibratory cycle was achieved did not alter these findings. In contrast, with a fixed vocal fold length the MU appeared more laterally as MFR increased, but, based on the relation with the mark, its location on the vocal fold did not change from its original position before increase of MFR.

Animals↗
PubMed1993

Renal function after sevoflurane or enflurane anesthesia in the Fischer 344 rat.

Sevoflurane is metabolized to inorganic fluoride, a potential nephrotoxin. To evaluate the nephrotoxic potential of sevoflurane, 1-yr-old male Fischer 344 rats were anesthetized with 10 minimal alveolar anesthetic concentration (MAC) h sevoflurane or enflurane with or without pretreatment with biotransformation-enhancing agents. Peak serum fluoride levels reached 35 microM with sevoflurane anesthesia after pretreatment with phenobarbital and 40 microM after enflurane anesthesia after pretreatment with isoniazid. One day after anesthesia, sevoflurane-anesthetized rats concentrated urine normally in response to subcutaneous administration of 1-deamino-8-D-arginine vasopressin and exhibited no increase in urinary excretion of N-acetyl beta-glucosaminidase. Isoniazid-treated, enflurane anesthetized rats developed a 31% reduction in maximal urinary concentrating ability and a 3.5-fold increase in excretion of N-acetyl-beta-glucosaminidase. Sevoflurane produced no evidence of fluoride-induced nephrotoxicity in noninduced or enzyme-induced rats. Under similar conditions, enflurane produced laboratory evidence of nephrotoxicity.

Anesthesia, Inhalation↗
PubMed1993

Observations on the blood and perineurial permeability barriers of surviving nerve allografts in immunodeficient and immunosuppressed rats.

The authors investigate whether there are any permeability changes in the endoneurial blood-nerve barrier and the perineurium-nerve barrier of surviving nerve allografts. In a normal nerve, the blood-nerve barrier regulates the passage of substances from endoneurial blood vessels into the endoneurium, whereas the perineurium-nerve barrier protects the endoneurium from agents that escape from permeable epineurial vessels and accumulate around the nerve. Nerves from ACI rats were transplanted into immunologically deficient nude rats or normal Fischer rats immunosuppressed with cyclosporin A. None of the nerve allografts was rejected. The blood-nerve barrier of nerve allografts at 2 and 6 weeks postoperatively was permeable to intravenously injected horseradish peroxidase, which spread into endoneurial tissue. Electron microscopy revealed that horseradish peroxidase escaped from endoneurial vessels through intercellular junctions between endothelial cells. At 24 weeks, the blood-nerve barrier of nerve allografts had recovered and the endoneurial vessels, like those in normal nerves, were impermeable to horseradish peroxidase. The perineurium-nerve barrier of nerve allografts remained impermeable to horseradish peroxidase at all times. Axons were grouped into numerous minifascicles at nerve anastomosis zones at 24 weeks. Each nerve fascicle was surrounded by an impermeable perineurium. These results demonstrate that regenerated axons in long-term surviving nerve allografts and at anastomosis zones are protected by permeability barriers. It is concluded that permeability barriers of nerve allografts are not permanently altered by a foreign environment (grafts to nude rats) even when immunosuppression with cyclosporin A is required to prevent allograft rejection (grafts to Fischer rats).

Animals↗
PubMed1993

[Histological analysis of aging ciliary body].

The aging changes in human ciliary body were studied by histological analysis. Thirty four autopsy eyes were fixed in 2.5% formalin and 1.0% glutaraldehyde mixture. The age distribution was 12 eyes below 50 years of age 13 eyes between 60 and 70 years of age, and 9 eyes over 80 years of age. Serial sections of the ciliary body were made parallel to the limbus and vertical to the ciliary processes. From four areas (transitional portion between pars plana and pars plicata, posterior portion of pars plicata, middle portion of pars plicata, and anterior portion of pars plicata) a central section was selected. Histological analysis was done with the use of Azur II stained light microscopic pictures. The basement membrane of non-pigmented epithelium below 50 years of age was thinner than between 60 and 70 years of age. This finding may be related with lowering aqueous humor secretion with aging. Non-pigmented epithelium, blood vessels in the stroma, and muscle fibers in muscle tissue showed aging changes. The pigment epithelium, basement membrane, and muscle fibers in muscle tissue did not show aging changes in light microscopical analysis, but study of their fine structure is necessary.

Aged↗
PubMed1993

[Cefuzonam penetration into cerebrospinal fluid].

We studied the penetration of cefuzonam (CZON) into the cerebrospinal fluid (CSF) in 20 patients with neurosurgical diseases. Influences of the presence of meningeal reaction and the intensity of brain damage on CSF penetration of CZON were also examined. Concentrations of CZON in serum and CSF were determined using the thin-layer cup method before and 1, 2, 4, and 6 hours after 2 g of CZON was administered intravenously. The serum concentration at 1 hour was 60.4 +/- 31.3 (mean +/- S.D.) microgram/ml, then rapidly decreased to 2.1 +/- 2.3 micrograms/ml at 6 hours. In contrast, the CSF concentration gradually increased, reached a peak level of 0.319 +/- 0.313 micrograms/ml at 4 hours and then slowly decreased to 0.273 +/- 0.249 micrograms/ml at 6 hours. The CSF penetration ration: CZON ([CSF]/[serum]) was 5.6% at 4 hours. The peak CSF concentration in patients with meningeal reaction (0.465 +/- 0.364 micrograms/ml at 2 hours) was about 2-fold higher than that in those without the reaction (0.249 +/- 0.223 micrograms/ml at 4 hours). The peak CSF concentrations in patients with slight, moderate, and severe brain damage were 0.231 +/- 0.133 micrograms/ml at 4 hours, 0.270 +/- 0.232 micrograms/ml at 4 hours, and 0.680 +/- 0.467 micrograms/ml at 2 hours, respectively. CSF penetration of CZON was augmented in patients with meningeal reaction or severe brain damage. These findings indicate that the concentration of CZON in CSF after intravenous administration is sufficient for treatment of meningitis or infections after neurosurgical operations caused by such bacteria as Escherichia coli, Klebsiella pneumoniae, Haemophilus influenzae, and Streptococcus pneumoniae.

Adult↗
PubMed1992

Changes in erythrocyte membrane fluidity by endotoxin in rats.

The effect of endotoxin on fluidity and lipid composition of the erythrocyte membrane was studied in rats following the intraperitoneal administration of endotoxin (30 mg.kg(-1) body weight). Erythrocyte membrane fluidity measured with 16-stearic acid spin label (16-SAL) was significantly decreased in the endotoxin-treated rats as compared with control. A decrease of lysophosphatidylcholine in the membrane lipid was evident in the endotoxin-treated rats. The cholesterol to phospholipid molar ratios and other phospholipid fractions did not differ significantly in the two groups. The levels of plasma Beta-glucuronidase activity and lipoperoxide were significantly increased in the endotoxin-treated rats when compared to controls. There were significant correlations between the parameter of 16-SAL in erythrocytes and plasma Beta-glucuronidase activities or lipoperoxide from both endotoxin-treated and control groups, P < 0.005 or P < 0.02 respectively. In conclusion endotoxin decreased rat erythrocyte membrane fluidity in vivo. Since membrane fluidity is closely related to the vital functions of the membranes, the change described could be related to the abnormality of cell membrane functions in endotoxin shock state.

Journal Article↗
PubMed1992

Skull base reconstruction in cases of intracranial teratoma extending into the extracranial structures.

Recently experienced were two cases of postnatally diagnosed intracranial teratoma, one a mature teratoma and the other an immature teratoma, both extending into the extracranial structures. In each case, tumor resection was performed in which a barrier was created between the intracranial and extracranial spaces with a temporalis muscle flap. The technical aspect of skull base reconstruction is described, and previously reported cases of intracranial teratoma involving the skull base are reviewed.

Brain Neoplasms↗
PubMed1991

[Clinical studies of isosorbide dinitrate spray in postoperative patients].

We investigated the effect of isosorbide dinitrate (ISDN) single spray, containing 1.25 mg of ISDN, on cardiovascular and respiratory functions in eight postoperative patients. Concentrations of plasma ISDN and its metabolites were also investigated. Hemodynamic as well as blood gas studies were performed at 4 points (before, plus 10, 30 and 60 minutes after administration of ISDN) and the blood levels of ISDN and its metabolites were measured at 5 points (before, plus 5, 10, 30 and 60 minutes after administration of ISDN). Mean arterial pressure (MAP), mean pulmonary arterial pressure (MPAP), cardiac index (CI), pulmonary capillary wedge pressure (PCWP) and central venous pressure (CVP) decreased significantly and heart rate (HR) increased significantly at 10 and 30 minutes after the spray. The maximum changes observed of each parameters were MAP 7%, MPAP 22%, CI 9%, PCWP 33%, CVP 36% and HR 6%. Systemic and pulmonary vascular resistance indices did not change significantly throughout the study. PaO2 decreased significantly only at 10 minutes after the spray. Plasma ISDN concentration showed the maximum value of 56.3 ng.ml-1 at 5 minutes after the spray. After this value, the concentrations decreased rapidly. From this study, we conclude that single spray of ISDN is effective in decreasing preload promptly, but it is not effective in decreasing afterload. When using the spray, we should pay attention to pulmonary oxygenation.

Adult↗
PubMed1990

Regrowth of damaged neurosecretory axons to fenestrated vessels of implanted peripheral tissues.

A major target of neurosecretory axons (NSA) is the basal lamina around fenestrated blood vessels (FBV) in the neural lobe of the pituitary gland. We have posed the question of whether there is neurovascular specificity. Do mature, regenerating NSA terminate selectively on the FBV of the neural lobe compared with the FBV of other tissues that normally are not innervated by NSA? Three types of tissue were transplanted between inbred Fisher rats. Fragments, about 1 mm3, of pineal, adrenal medulla, and neural lobe were grafted bilaterally to the hypothalamic, retro-chiasmatic area, which includes bundles of NSA from supraoptic and paraventricular neurosecretory nuclei exclusively, but no FBV. Two and 4 weeks later, the grafts were prepared for the immunohistochemical localization of NSA and for electron microscopy. NSA-FBV proximity was measured, and the number of NSA, FBV, and of NSA-FBV associations was counted per surface area of each graft. Regenerating NSA can associate as closely with FBV of other tissues as they can with the FBV of the neural lobe. There does not appear to be specificity with respect to the closeness of association between neurosecretory terminals and fenestrated capillaries. However, the number of these associations is greater in neural lobe grafts than in adrenal or pineal grafts at 4 weeks. The number of FBV is also greatest in neural lobe grafts at this time, an increase that would provide a greater opportunity for NSA-FBV associations.

Adrenal Medulla↗
PubMed1988

[A case of clivus chordoma showing hemorrhage in the posterior fossa].

We are reporting a rare case of clivus chordoma with fatal hemorrhage in the posterior fossa. A 38-year-old woman afflicted with sudden onset of severe headache and vomiting. On neurological examination, she was mildly lethargic. She had slight dysarthria and nystagmus, but no cranial nerve abnormalities. Craniogram revealed erosive changes in the right petrous bone. CT scan showed a massive intracerebellar hemorrhage and isodense mass in the sphenoid sinus, which were not enhanced by contrast medium. She became comatose and died 3 days later. No operation was performed. Autopsy revealed massive hemorrhage in the posterior fossa and yellowish, gelatinous tumor extending from the right clivus to the sphenoid sinus. Histological examination showed a chordoma. This case demonstrates that the hemorrhage associated with brain tumor, especially in posterior fossa, produces a significant sudden elevation of intracranial pressure and leads clinically to a rapid loss of consciousness and death soon after the onset.

Adult↗