Remarkable postcataract against-the-rule astigmatism after phacoemulsification in 83 of 809 cases

We analyzed 83 cases of remarkable postcataract against-the-rule (AR) astigmatism (greater than 1.5D) occurring in a total of 809 Kelman's phacoemulsification aspiration procedures, all using 10-0 polyester sutures in a double-running fashion to close the corneoscleral incisions. All operations were done by one surgeon, using the same surgical procedure and the same number of sutures. The induction and spontaneous regression of several types of astigmatism were analyzed over six months. In cases of preoperative oblique and AR astigmatism, shifts (2.09 +/- 0.22D, 1.93 +/- 0.13D, respectively) after the first week were much smaller than those of preoperative with-the-rule astigmatism. Thereafter, degrees of oblique and AR astigmatism increased and remained higher even six months after surgery. The induction and spontaneous regression of postoperative AR astigmatism was similar to that of oblique astigmatism. Compression of the lids on the eye may be a more important factor than previously considered.

Effects of dorsal root entry zone lesions on CSF and plasma neuropeptides and catecholamines

Effects of dorsal root entry zone lesions (DREZLs) on cerebrospinal fluid (CSF) and plasma concentrations of neuropeptides, catecholamines, and cyclic nucleotides were studied in 9 patients with intractable chronic pain. Contents of beta-endorphin-like-material in CSF decreased in all patients 12-17 days following DREZLs during which complete to good pain relief was achieved. Contents of beta-endorphin-like-material in CSF increased again about one month after DREZLs in two and remained unchanged in one of three patients tested, who complained of partial reappearance of pain. Contents of beta-endorphin-like-materials in plasma showed no significant changes after DREZLs. Substance P, noradrenaline, adrenaline, and cyclic nucleotide levels in both CSF and plasma were variable among the subjects and did not change significantly following the operations. Thus, the results suggest that production of beta-endorphin-like-material in the central nervous system is decreased by DREZL, though the increase in its turn-over might not be neglected. The mechanisms of the decrease in contents of beta-endorphin-like-material in CSF after DREZLs were discussed in terms of our current knowledge of pain and pain inhibitory systems.

Changes in intracellular pH of mouse hippocampal slices responding to hypoxia and/or glucose depletion

Effects of hypoxia and/or glucose depletion on apparent intracellular pH, (pHi)app, were studied in hippocampal slices of mouse brain using the fluorescence pH indicator BCECF (2',7'-bis(carboxyethyl)carboxyfluorescein). In the presence of glucose (11 mM), (pHi)app of the CA1 pyramidal cell layer decreased with hypoxia but rapidly recovered with reoxygenation. The response in (pHi)app to hypoxia was consistent with changes in lactate content. By superfusion with a hypoxic and glucose-devoid solution, (pHi)app decreased in the first 5 min, but then increased in two phases: during a 5- to 7-min period and again during the latter period of superfusion. BCECF fluorescence rapidly diminished in this latter period. These changes in (pHi)app could not be explained only by the lactate content in the slices. Some other mechanisms may also regulate the (pHi)app in the slices during and after hypoxia and glucose depletion.

[Digital imaging microscopy for intracellular Ca2+ in cultured single rat vascular smooth muscle cells using fluorescent Ca2+ indicator "fura-2"]

We presented the principle and methodology of digital imaging microscopy for intracellular Ca2+ in cultured single vascular smooth muscle cells of the rat using fluorescent Ca2+ indicator "fura-2". The methods seemed useful for studying the physiological and pathological phenomena in a single smooth muscle cell. Analysis of the spatial and temporal dynamics of intracellular Ca2+ might be crucial for studying the active sites of vasoactive or anesthetic drugs in a vascular smooth muscle cell as well as for understanding pathophysiology of the arterial spasm.

Outcome of preoperative against-the-rule astigmatism after phacoemulsification: characteristic changes over time. Part II

To determine the outcome of preoperative against-the rule (AR) astigmatism among 1,648 phacoemulsification and aspiration (PEA) procedures, we analyzed the post-cataract time course of astigmatism over 6 months in 618 eyes divided into three groups. In preoperative AR astigmatism less than 0.75 dptr (n = 208), the astigmatism increase 1 week postoperatively was rapid. In preoperative AR astigmatism greater than or equal to 1.5 dptr (n = 185), no difference in the power of astigmatism was apparent between 1 and 3 months postoperatively. The third group (0.75 less than or equal to preoperative AR astigmatism less than 1.5 dptr, n = 143) showed intermediate characteristics. The eyes with preoperative low AR astigmatism showed exacerbation of astigmatism after the PEA procedure, whereas the degree of astigmatism, corneal curvatures and the rate of AR astigmatism became lower in the eyes with higher preoperative AR astigmatism.

Sudden against-the-rule astigmatism 6 months after intraocular lens implantation with the Kelman phacoemulsification procedure: 4 of 809 cases

Of 809 eyes that underwent the Kelman phacoemulsification and aspiration (KPE) procedure, we report on 4 patients (0.49%) who developed sudden against-the-rule (AR) astigmatism after intraocular lens implantation. These patients had had with-the-rule astigmatism preoperatively to 3 months postoperatively and suddenly developed AR astigmatism 6 months after surgery. To study the development and progression of AR astigmatism in these patients (group A), we compared their 6-month time course with that of 257 patients (group B) with postoperative AR astigmatism. In group A, the degree of astigmatism was not significantly different from group B astigmatism preoperatively (1.03 +/- 0.16 vs. 1.04 +/- 0.04 dptr) and 6 months postoperatively (1.32 +/- 0.13 vs. 1.26 +/- 0.05 dptr). However, 1 week postoperatively, the astigmatism of the 4 cases was much greater (5.72 +/- 0.14 dptr) than that of the others (2.32 +/- 0.07 dptr). These rare 4 cases, which had no other unusual characteristics, are indicative of the importance of a careful follow-up even if the post-KPE course seems uneventful.

Postcataract against-the-rule astigmatism after phacoemulsification procedure. Characteristic changes over time

To further determine whether postoperative astigmatism is related to the amount of preoperative astigmatism, we analyzed two types of against-the-rule (AR) astigmatism induced by phacoemulsification and aspiration (PEA) procedures. The operations all utilized 10-0 polyester (Mersilene) in double running fashion for the closure of the corneoscleral incisions. The induction and spontaneous regression of several types of astigmatism were analyzed over 6 months. Surgery was all done by one surgeon, with the same surgical procedure and the same number of sutures. In postoperative AR astigmatism less than 0.7 D at 6 months, although the amount of the astigmatism 1 week postoperatively was remarkably increased (2.66 +/- 0.17 D), postoperative astigmatism was decreased 6 months following surgery. On the other hand, in postoperative AR astigmatism greater than 1.5 D at 6 months, the power of the astigmatism 1 week postoperatively (2.12 +/- 0.13 D) was not much higher than the preoperative level (1.38 +/- 0.08 D), but tended to continue increasing even 6 months after surgery. There was no difference in the power of astigmatism between 1 and 3 months postoperatively. The eyes with preoperative astigmatism (e.g. 1.38 +/- 0.08 D) and especially preoperative AR astigmatism (e.g. 1.60 +/- 0.11 D), showed an increase of their astigmatism after the PEA procedure. We discussed some risk factors which may induce greater postoperative AR astigmatism.

Mechanoreceptors of the hard palate of the Mongolian gerbil include special junctions between epithelia and Meissner lamellar cells: a comparison with other rodents

As a part of our comparative morphological study of mechanoreceptors in rodent oral mucosae, the hard palate of the mongolian gerbil (a kind of sand rat) was investigated by light and electron microscopy. Subepithelial connective tissue papillae of palatine rugae contained a dense distribution of lamellated corpuscles that showed an ultrastructure similar to that of Meissner corpuscles of primates. The corpuscles in the palate of the mongolian gerbil, however, frequently formed compound large corpuscles with a palisade-like extension. Antemolar rugae predominated in containing such compound "Meissner" corpuscles. Superficial cytoplasmic lamellae of the corpuscles closely adhered to overlying epithelial cells without an intervening basal lamina. Although a small number of simple corpuscles was seen in the first antemolar rugae, no similar corpuscles were encountered in other parts of the palate. On the other hand, numerous Merkel cell-nerve endings were seen in epithelial pegs and sometimes in epithelial ridges of palatine rugae. Quinacrine labelling showed that intermolar rugae contained a rather dense distribution of Merkel cells in comparison with antemolar rugae. The present and previous data indicate that the pattern of palatine mechanoreceptors of the mongolian gerbil is analogous to that of the mouse, but not of the rat.

Short-term mineralization of dentin and enamel in the mouse embryonic molars cultured in serum-free, chemically-defined medium

The present study was designed to demonstrate the short term mineralization of dentin and enamel, and to investigate the effects of sodium beta-glycerophosphate (Na-beta-GPO4) on calcification in a serum-free, chemically-defined medium. The first mandibular molars at the bell stage dissected from 18-day-old mouse embryos were used as explants, which were cultured by an improved flotation method. Calcification of enamel in the 18-day-old embryonic molars occurred within the 6th day of culture. In another experiment, the molar germs were cultured in a serum-free, chemically-defined medium supplemented with 1, 5 and 10 mM Na-beta-GPO4. Promotion of tooth mineralization was recognizable at very low concentrations, such as 1 mM Na-beta-GPO4, in 18-day-old embryonic tooth germs. The culturing system reported here shortens the time required for dentin and enamel calcification to one half or one third of that reported previously and therefore should prove useful for examining regulations for cytodifferentiation and morphogenesis in tooth germs and the mineralization of dentin and enamel.

Differential effects of protein kinase C activation on catecholamine secretions evoked by stimulations of various receptors in the rat adrenal medulla

Catecholamine secretions during continuous receptor stimulations by histamine, muscarine and bradykinin in the rat adrenal medulla commonly consisted of two phases, a transient initial secretion followed by a sustained secretion. On activating protein kinase C (PKC) by phorbol dibutyrate (PDBu), both phases of histamine-evoked secretion were inhibited whereas the initial phase alone was inhibited with muscarine. In contrast, bradykinin-evoked secretion as a whole was potentiated. Similar modes of modulations were exhibited when the secretions with these agonists were elicited in muscarine- or bradykinin-pretreated medullae in which PKC had been activated by endogenous processes. It is suggested that PKC may selectively affect the receptors or/and GTP-binding proteins to cause the differential effects on the secretory response in the rat adrenal medulla.

Observation of spinal canal and cisternae with the newly developed small-diameter, flexible fiberscopes

Small-diameter (0.5-, 0.9-, and 1.4-mm) flexible fiberscopes were developed for visual diagnosis of spinal canal diseases. The fiberscopes were introduced via a Tuohy needle into the subarachnoid and epidural spaces of ten patients with various pain syndromes. Clear visualization of the subarachnoid space was achieved using the fiberscopes. The epidural space could be visualized only during withdrawal of the fiberscope. In five cases, the fiberscope could be advanced up to the level of the cisternae without causing the patient any discomfort. A slight headache and transient fever were noted after the examination in five and two cases, respectively, but no other complications occurred. Interestingly, preexisting pain diminished (two cases) or disappeared (one case) after the myeloscopy in three of five cases in which the myeloscopy revealed aseptic adhesive arachnoiditis. Further studies should be carried out to evaluate the usefulness of this technique.

[Anesthetic management of pheochromocytoma by continuous intravenous injection of prostaglandin E1]

We had five cases of surgical removal of pheochromocytoma by continuous intravenous injection of prostaglandin E1. During anesthesia, we used Swan-Ganz catheter for circulatory monitoring and measured plasma catecholamines. When PGE1 dose was increased from 0.05 to 0.1 and 0.15 microgram.kg-1.min-1, total systemic vascular resistance and mean arterial pressure were decreased but heart rate and cardiac output were not significantly altered from the preanesthetic values. Plasma catecholamines were also similar to the preanesthetic values. Therefore, the results suggest that the mechanism of suppression of hypertension by PGE1 is by affecting vascular beds directly rather than by diminishing catecholamine excretion from sympathetic nerve and adrenal medulla. During manipulation of pheochromocytoma, mean arterial blood pressure increased extremely. Although PGE1 was injected at a rate of 0.3 to 0.5 microgram.kg-1.min-1 in some cases, we could not suppress the elevation of blood pressure. PGE1 alone could not normalize blood pressure and heart rate, and other cardiovascular agents were necessary.

Structure of triphosphonoglycosphingolipid containing N-acetylgalactosamine 6-O-2-aminoethylphosphonate in the nervous system of Aplysia kurodai

A phosphonoglycosphingolipid, named F-21, was found in the nervous system of Aplysia kurodai by two-dimensional thin-layer chromatography (Abe, S., Araki, S., and Satake, M. (1986) Biomed. Res. (Tokyo) 7, 47-51). F-21 was isolated from the nervous tissue of Aplysia in this study, and its chemical structure was characterized as follows, where 2-AEP is 2-aminoethylphosphonate. (Formula; see text) The major aliphatic components of the ceramide portion were palmitic acid (75%), stearic acid (22%), octadeca-4-sphingenine (43%), and anteisononadeca-4-sphingenine (54%). Some information on the steric interactions in the sugar moiety was obtained by NMR spectroscopy. The ring protons of the internal galactose, H1, H3, and H4 and the H3 of the side chain galactose were shifted, as compared to the corresponding protons of dephosphonylated F-21. This may indicate the interactions between the 2-AEP residue of N-acetylgalactosamine and the internal galactose and between the N-acetyl group of N-acetylgalactosamine and the side chain galactose, implying a sterically restricted and unique structure that may relate to some biological functions of F-21.

Stimulatory effect of guanine nucleotides on prostaglandin E1 binding to murine renal outer medulla

Prostaglandin E1 (PGE1) specifically bound to the membrane prepared from murine renal outer medulla. The extent of binding of [3H]PGE1 to the membrane was increased about 4-fold by guanosine triphosphate (GTP) and its analogs, but the dissociation of bound [3H]PGE1 from the membrane was in turn enhanced by GTP gamma S. Scatchard plot analyses revealed that GTP gamma S increased the binding affinity more than 2-fold without a major change in the number of binding sites. When [3H]PGE1-bound proteins were cross-linked in the membrane by dithiobis (succinimidyl propionate), bound [3H]PGE1 was no longer dissociated by GTP gamma S treatment, suggesting that cross-linking produced a stable complex of PGE receptor with a GTP-binding protein. The cross-linked [3H]PGE1-specifically bound proteins solubilized from the membranes labeled with [3H] PGE1 in the presence or absence of GTP gamma S were eluted as an apparently single radioactive peak at the same position of Mr = 15000 by gel filtration, indicating that the PGE receptor forms a complex with a GTP-binding protein regardless of the treatment with GTP gamma S by which [3H]PGE1 binding is promoted. The ability of GTP gamma S to stimulate [3H]PGE1 binding was eliminated by pretreatment of the membrane with pertussis toxin, but not cholera toxin, indicating that the PGE receptor is coupled to a pertussis toxin-sensitive GTP-binding protein.

[Surgical treatment of hypoplastic left heart syndrome: a successful case report]

A successful case of Norwood operation for a 5-day-old infant with hypoplastic left heart syndrome is reported. Norwood procedure and central shunting with a 4 mm PTFE tube was performed. Cerebral and coronary artery were perfused independently during reconstruction of aorta in order to shorten the time of circulatory arrest. Post operative UCG documented un-obstructive systemic output from the right ventricle, well regulated pulmonary arterial blood flow and widely patent interatrial communication. This baby was discharged the hospital 66 days after surgery. He has been clinically well for six month after the operation.

The ultrastructure of the ganglionated nerve plexus in the nasal vestibular mucosa of the musk shrew (Suncus murinus, insectivora)

A ganglionated nerve plexus (GNP) found in the nasal vestibular mucosa of the adult musk shrew, and most likely belonging to the nervus terminalis, was studied by electron microscopy. The GNP, which contained ganglion cells and both myelinated and unmyelinated nerve fibers, was located in the subepithelial layer of the mesial vestibular mucosa of the snout processes. The ganglion cells were characterized by an eccentrically located round nucleus, dispersed mitochondria and Golgi apparatuses, and many small vesicles. Nissl bodies were rare. The ganglion cells, solitary or in a small group, were entirely covered with satellite cell sheaths. Semiserial sections suggested that a given ganglion cell directly extends one nerve process and plural modified cilia. There were no synaptic contacts between the ganglion cells and efferent nerve elements. On the other hand, it was seen that the epithelium overlying the GNP contained many nerve terminals which probably originated from the GNP. It is suggested that the ganglion cells in the nasal vestibular GNP of the musk shrew represent primary sensory neurons.

Endochondral calcification by hypertrophic chondrocytes in the Meckel's cartilage grafted into the isogenic mouse spleen

We found that when the midsection of Meckel's cartilage bars obtained from mice on the eighteenth day of gestation were grafted into isogenic mouse spleen, chondrocytes induced an endochondral calcification. Concurrent with the onset of calcification throughout Meckel's cartilage matrix, periodic banded thick collagen fibrils and matrix vesicles were observed around the chondrocytes. Although most of the chondrocytes prior to grafting were hypertrophic cells, they survived for seven days in the splenic tissue and had well-developed secretory organelles. The cells which were surrounded by calcified matrix were relatively small, spherical, and showed a morphology closely resembling that of osteocytes. These findings suggest that the life span of hypertrophic chondrocytes is influenced by the microenvironment of the spleen.

Effects of isoflurane on spinal inhibitory potentials

The effects of isoflurane on segmental spinal cord potentials and heterosegmental slow positive potentials in response to fore- and hindpaw stimulation were studied in the rat. The heterosegmental slow positive potential and late (second) component of the slow positive wave (P2) of segmental spinal cord potential, thought to be primary afferent depolarization, an agent of presynaptic inhibition activated by a feedback loop via supraspinal structures, were greatly suppressed by the anesthetic. In contrast the negative wave (N1) of segmental spinal cord potential, believed to be synchronized activity of dorsal horn neurons, was only minimally affected. No differential effects of isoflurane on spinal cord potentials activated by fore- and hindpaws were found. Thus, the inhibitory activities of the spinal cord, particularly those produced by a feedback loop via supraspinal structures, are suggested to be highly vulnerable to isoflurane.

Endothelial modulation of norepinephrine-induced constriction of rat aorta at normal and high CO2 tensions

Endothelial modulation of norepinephrine (NE)-induced constriction of the isolated rat aorta was studied at normal (PCO2, 41 +/- 0 mmHg) and high CO2 tensions (PCO2, 91 +/- 1 mmHg). In preparations with intact endothelium, increased CO2 tension resulted in rightward shift of the NE dose-response curve with attenuation of maximal contraction. This effect of CO2 was not modified by indomethacin. Treatment with hemoglobin or rubbing of the endothelium meant that increased CO2 tension still resulted in rightward shift of the NE dose-response curve but without altering the maximal contractile response. The basal guanosine 3',5'-cyclic monophosphate (cGMP) levels in control and NE-treated aortic preparations were not affected by increasing the CO2 tension. Thus the inhibitory action of CO2 on NE-induced contraction in the presence of endothelium may not be derived from facilitation of endothelium-derived relaxation factor (EDRF)-induced cGMP synthesis. Increasing the CO2 tension attenuated the sustained contraction induced by the addition of NE and Ca2+ (2.5 mM) to intact endothelium preparations previously bathed in Ca2(+)-free solution. Further addition of Ca2+ (total 5.0 mM) did not increase the contraction. These findings suggest that the intrinsic activity of NE is greatly modified by endothelium at a high CO2 tension. Vasodilation during hypercapnia may be induced at least in part by synergistic actions of EDRF and CO2 on smooth muscle cells.

A comparative electron microscopic analysis of mechanoreceptors in the hard palate of the mouse (Mus musculus; Rodentia) and the musk shrew (Suncus murinus; Insectivora)

These mechanoreceptors were studied with particular regard to their type and the distribution. In both species they were concentrated in the crests of transverse palatine rugae. In the mouse, Meissner corpuscles, glomerular corpuscles, and Merkel cell nerve endings were seen in every palatine ruga, though the first antemolar ruga also contained simple and atypical lamellated corpuscles. In contrast, the palatine rugae of the musk shrew contained only simple corpuscles and Merkel cell nerve endings. Meissner corpuscles in the mouse palate were frequently aggregated to form a palisade-like, huge corpuscle. Anterior intermolar rugae especially contained a larger number of such huge corpuscles. Simple corpuscles in the palate of the musk shrew were more densely distributed in the anterior than in the posterior rugae. In both species Merkel cell nerve endings were localized within epithelial downgrowths of the rugal crest. These downgrowths tended to increase in number anteroposteriorly.

Structure of phosphonoglycosphingolipid containing pyruvylated galactose in nerve fibers of Aplysia kurodai

A phosphonoglycosphingolipid, designated as FGL-IIb, was identified in nerve fibers of Aplysia kurodai by two-dimensional thin layer chromatography (Abe, S., Araki, S., and Satake, M. (1986) Biomed. Res. (Tokyo) 7, 47-51). FGL-IIb was isolated from the nervous system of A. kurodai by Iatrobeads column chromatography using three solvent systems. Pyruvic acid was identified by thin layer chromatography as its 2,4-dinitrophenylhydrazone and established by permethylation studies to be attached as a ketal to O-3 and O-4 of the terminal galactose of the oligosaccharide chain in FGL-IIb. By sugar analysis, permethylation studies, fast atom bombardment-mass spectrometry, and proton magnetic resonance spectrometry, the structure of FGL-IIb was concluded to be [3,4-O-(1-carboxyethylidene)]Gal beta 1----3GalNAc alpha 1----3(Fuc alpha 1----2) (2-aminoethylphosphonyl----6)Gal beta 1----4Glc beta 1----1ceramide. Its major aliphatic components were palmitic acid, octadeca-4-sphingenine and anteisononadeca-4-sphingenine. This is the first report of the occurrence of pyruvylated galactose as a constituent of animal sphingolipid.

A simple, disposable, and improved organ culture system for maintaining three-dimensional development of mouse embryonic molars

Mandibular first molars from 17-d-old mouse embryos were cultured in vitro for 2 to 4 d by a simple, disposable, improved floatation method. This method consisted of using a 24-well multidish and a plastic culture chamber with a membrane filter. The improved floatation method, as well as our previous method, was capable of the three-dimensional development of tooth germs. Cytodifferentiation of odontoblasts and ameloblasts and formation of extracellular matrices were accelerated by the present culture system, in comparison with our previous method. All the molars cultivated by this method were very similar in morphology to in vivo. On Day 2 of culture the terminal cytodifferentiation of odontoblasts and the formation of predentin were ascertained in the bucco-lingual sections of the cultured molars. A thick layer of predentin was formed at the tip of the cusp and gradually decreased toward the cervical loop and the fissure between the buccal and lingual cusps. On Day 4 in vitro, secretory ameloblasts produced enamel matrix, and the mineralized enamel showed showed prismatic structure very similar to that in vivo. Dentin and predentin also were normal in ultrastructure. The extracellular matrices (enamel, dentine, and predentin) were formed in line with the pattern of the cusp and the formation of matrices normally started at the tip of the cusp. We conclude that the three-dimensional development of whole tooth germs in vitro may be very important for normal expression of the developmental program intrinsic to mouse embryonic molars.

In vitro effects of calcitonin and/or parathyroid hormone on odontogenesis of mouse embryonic molars

Mandibular first molars of mouse embryos were cultivated for examination of the effects of calcitonin (CT) and/or parathyroid hormone (PTH) on the odontogenesis of the molars, and for determination of whether and how CT, which is a PTH antagonist, has an influence on the effect of PTH on odontogenesis. On the second day, the inner enamel epithelium in the control group had already differentiated into pre-ameloblasts. Typical odontoblasts had secreted a layer of predentin. On the fourth day of culture, the pre-ameloblasts achieved terminal differentiation into secretory ameloblasts, and enamel and dentin had already been deposited. PTH (1 unit/mL) inhibited the odontogenesis of the cultured molars during the designated culture periods (two and four days), while CT (0.5 unit/mL) stimulated odontogenesis. On the second day, the development of the molars in the CT + PTH group showed an intermediate stage between the control and PTH-treated explants, but on day 4 it corresponded to that of the controls. Moreover, when the molars exposed to PTH for two days were untreated and treated with CT for an additional two days, the former produced a small quantity of enamel matrix, while the latter formed a large amount of the matrix. These histological findings were also supported by a morphometric analysis of the enamel matrix in the cultured molars. The present results suggest that CT stimulates, but PTH suppresses, the odontogenesis of the mouse embryonic molars, and that CT is an antagonist to the inhibitory effect of PTH on odontogenesis.

Epithelial cytodifferentiation and extracellular matrix formation in enamel-free areas of the occlusal cusp during development of mouse molars: light and electron microscopic studies

Mandibular first molars in mice ranging in age from 18 days prenatal to 5 days postnatal were used for light and electron microscopic examinations of the enamel-free area (EFA) during development of the occlusal cusp (mesiobuccal cusp). Notable morphological changes in the inner enamel epithelium and the cells of the stratum intermedium were observed. At prenatal age of 18 days, the inner enamel epithelium of the EFA (EFA epithelium) was composed of a layer of columnar cells and covered by the cells of the stratum intermedium. Two days after birth, the EFA epithelium was made up largely of preameloblasts, with mitochondria located in the proximal side of the cells toward the stratum intermedium. The cells of the stratum intermedium were irregularly shaped, with wide intercellular spaces between them. At a postnatal age of 3 days, most of the EFA epithelial cells resembled maturation-stage ameloblasts, being short and columnar in shape and having nuclei located in their proximal side. Distal cell membranes were folded, and mitochondria were scattered throughout the cytoplasm. In 4-day-old mice, the EFA epithelium was found to be formed of short columnar or cuboidal cells with distinct intercellular spaces. The cells of the stratum intermedium could no longer be detected, and cells of the EFA epithelium could not be distinguished from those of the stellate reticulum. Odontoblasts of the EFA were arranged and polarized parallel to the basal lamina, and odontoblastic processes extended toward the cusp tip. The orientation of thin and thick collagen fibers within predentin and dentin was also parallel to the basal lamina. Even after dentin mineralization, disrupted basal lamina and long, aperiodic, fine fibrils were found between the epithelium and the dentin. Following the disappearance of the basal lamina and fine fibrils, stippled material and crystals appeared on the dentin surface. The mineralized matrix, which x-ray microanalytical energy peaks identified as containing calcium and phosphorus, was continuous with enamel in the distal slope of the cusp at the cusp tip. Thus, the inner enamel epithelium of the EFA differentiated into secretory cells capable of enamel-like matrix formation.(ABSTRACT TRUNCATED AT 400 WORDS)

Intraperineural localization of lamellated sensory corpuscles in the skin and oral mucosae of the adult cat and miniature pig

Lamellated sensory corpuscles in the perioral tissues of the adult cat and the adult miniature pig were studied by light and electron microscopy. In the cat lip, over half of the lamellated corpuscles existed in an aggregate form associated with other nerve elements and blood capillaries in peripheral nerve swellings, while the remainder existed in an isolated form. Conversely, almost all the lamellated corpuscles in the miniature pig existed in an aggregate form in nerve swellings. Most of the intraperineural lamellated corpuscles showed ultrastructural characteristics of simple corpuscles. However, some of the intraperineural lamellated corpuscles exhibited interlaced arrangements of tortuous axon terminals and cytoplasmic lamellae resembling the arrangement in Meissner corpuscles. Immunohistochemical staining using anti-neuron specific enolase also revealed the presence of intraperineural, Meissner-like corpuscles in the cat lip. This study indicates that intraperineural localization of lamellated corpuscles is common in carnivora and artiodactyla and that the intraperineural lamellated corpuscles are heterogeneous in their ultrastructural pattern.

[The metabolism of glucose monitored by 13C-NMR in the gerbil brain in vivo-natural course and application to the ischemic model]

Glucose metabolism is altered in various pathologic conditions in the brain, i. e. ischemia, epilepsy and hypoglycemia. Therefore, analysis of glucose metabolism in pathologic conditions needs careful investigation of that in steady state. 13C-NMR method allows continuous sequential monitoring of changes in metabolism of glucose in vivo. The natural abundance of 13C is quite low (1.1%) and by administering 13C labelled in various skeleton in glucose, it is possible to monitor the metabolites in vivo. In this study, 13C glucose labelled in 1-position of carbon was employed to investigate the metabolic pathways in the control and transient ischemic gerbil brain with reperfusion. Male mongolian gerbils weighing 60-80 g were employed in this study. The gerbils were anesthetized by intraperitoneal administration of pentobarbital. The right skull was exposed and a surface coli was placed directly above the skull bone. After the operation, the animals were fastened to the NMR probe vertically. 500 mg/kg of [1-13C] glucose was injected via femoral catheter. 13C-NMR spectra were serially obtained before and after injection with GX-270 NMR spectrometer (JEOL, Tokyo, Japan, 6.34 T). In other series of experiments, 30 minutes of cerebral ischemia were induced after 15 minutes of glucose injection by the bilateral common carotid artery occlusion. In the normal gerbil brain, after administration of [1-13C] glucose (500 mg/kg), alpha and beta-anomers of [1-13C] glucose peak appeared abruptly and reached its peak level at 7.5-15 min acquisition period. The C2 peak representing glutamate and/or glutamine appeared later. The C3 and C4 peak started to appear even later at 30-40 min.(ABSTRACT TRUNCATED AT 250 WORDS)

Morphogenesis of mineralized tissues induced by neonatal mouse molar pulp isografts in the spleen

Tooth pulps dissociated intact with EDTA were isografted for up to 40 days, and examined by light and electron microscopy for hard tissue morphodifferentiation. Grafts formed tubular dentine and osteodentine. Tubular dentine, penetrated regularly by elongated odontoblast processes, resembled normal dentine and was formed when the original odontoblasts continued normal matrix secretion. Osteodentine was formed by spindle-shaped cells with large round nuclei which presumably were transformed pulp cells, and incorporated the same elements as found in cells of non-tubular dentine. Occasionally, odontoblasts were contiguous with both the regular dentine and the osteodentine. Thus in EDTA-dissociated pulps transplanted to the spleen, the original odontoblasts produce tubular dentine and other pulp cell differentiate to form osteodentine.

Changes in spontaneous firing patterns of rat hippocampal neurones induced by volatile anaesthetics

1. The effects of the volatile anaesthetics, halothane, isoflurane and enflurane, on rat hippocampal CA1 and CA3 neurones in in vitro preparations were studied by intracellular recording methods. 2. The three anaesthetics, at concentrations similar to those used clinically (0.2-1.2 mM), initially increased and then subsequently decreased the spontaneous firing of CA1 neurones without affecting the resting membrane properties or the EPSPs evoked by focal stimuli. 3. The anaesthetics at these concentrations depressed both the fast after-hyperpolarization of the soma spike and the post-tetanic hyperpolarization induced by repetitive stimulation. They also decreased the IPSPs evoked by focal stimuli. 4. The threshold for spike generation was gradually elevated by as much as 4-6 mV during application of the anaesthetics at these concentrations. The subthreshold potential oscillations (which are likely to be associated with periodic alterations in non-inactivating Ca2+ and Na+ currents) were enhanced in the low concentrations (0.2-0.5 mM), but were depressed in the high concentrations (0.8-1.2 mM). 5. The results suggest that the transient increase in the firing frequency was caused by a depression of both the spike after-hyperpolarization and the post-tetanic hyperpolarization, and that the reduction of spontaneous firing was mainly due to an elevated threshold for spike generation. 6. The three anaesthetics altered the pattern of spontaneous spike-firing in CA3 neurones from solitary spiking to burst firing without affecting the resting membrane properties. 7. The effects of the anaesthetics on the active membrane properties and the postsynaptic potentials in CA3 neurones were similar to the effects in CA1 neurones. 8. In the majority of CA3 neurones, soma spikes elicited by depolarizing current pulses were followed by a Ca2+-dependent after-depolarization, which was in turn followed by a prolonged after-hyperpolarization (post-burst hyperpolarization). The anaesthetics facilitated the after-depolarizing potential, while they depressed the post-burst hyperpolarization. Combination of the two effects would give rise to the highly stereotyped burst (about 1 Hz in frequency) in the presence of the volatile anaesthetics.

Influence of 1,25-dihydroxyvitamin D3 on cell proliferation during odontogenesis of the mouse embryonic molars in vitro

Mandibular first molars from 17-day-old mouse embryos were cultured for 2 and 4 days in alpha-MEM supplemented with 10% newborn bovine serum containing 0.02% ethanol or 0.1, 1.0 or 10 ng/ml 1,25-(OH)2D3. After embedding, every 6th section was stained and mitotic features of inner dental epithelium (IDE) and dental papilla cells (DP) were counted under a light microscope. On the 2nd day, no significant differences were observed in the IDE and DP mitotic indexes among the control, ethanol, and the three vitamin D groups. On the 4th day, the indexes for all groups decreased. But the IDE indexes for all vitamin D groups were significantly different from those for the control (P less than 0.01) and ethanol (P less than 0.05) groups, whereas the DP index was significant (P less than 0.05) only in the 10 ng/ml vitamin D group. The present results suggest that vitamin D3 may have an influence on cell proliferation of IDE and DP in mouse embryonic molars in vitro.

Relation between spinal cord and epidural blood flow

To test applicability of monitoring regional spinal cord blood flow by measuring regional epidural blood flow, both were simultaneously measured by the hydrogen clearance method in response to changes in PaCO2 and mean arterial blood pressure in rats anesthetized with pentobarbital. An excellent correlation was found between regional spinal and epidural blood flow over a physiological range of PaCO2 (27.8-66.7 torr) and blood pressure (30-130 torr), while a poor correlation was demonstrated between regional spinal or epidural blood flow and regional muscle blood flow in response to these same physiological parameters. Moreover, the rates of change in regional spinal and epidural blood flows were almost the same in response to both PaCO2 and blood pressure. These results suggest that both regional spinal and epidural blood flow are regulated by a similar mechanism and suggest that regional spinal cord blood flow can be monitored by regional epidural blood flow.

Effects of pentobarbital and ketamine on brain injury-induced anti-ischemic activity

Survival rates following incomplete brain ischemia induced during pentobarbital anesthesia were significantly higher in mice with a minor brain injury, inflicted one week before, than in those given a sham operation. Improvement of the survival rates in mice with brain injury, however, became insignificant when brain ischemia was imposed during ketamine anesthesia, suggesting that the actions of certain factors or protective mechanisms against brain ischemia, developed by brain injury, are antagonized by ketamine and/or potentiated by barbiturate anesthesia.

Effects of hypoxia on rat hippocampal neurones in vitro

1. The effects of hypoxia on the rat hippocampal CA1 neurones in tissue slices of the rat brain were studied in vitro by intracellular recording. 2. In response to superfusion of a hypoxic medium equilibrated with 95% N2-5% CO2, a majority of the neurones showed a hyperpolarization of 5-15 mV in amplitude and 4-12 min in duration. The hyperpolarization was, in turn, followed by a slow depolarization which within 20 min of hypoxic exposure reached a plateau level of about 25 mV above the pre-hypoxic resting potential. Both the initial hyperpolarization and subsequent depolarization were associated with a reduction in membrane resistance. 3. The hyperpolarization reversed in polarity at a membrane potential of -83 mV. There was an almost linear relationship between amplitude of the hyperpolarization and membrane potential. The hyperpolarization was markedly enhanced in potassium-free media and was depressed in high-potassium solutions. 4. The hyperpolarization was not significantly affected by low-chloride or low-sodium medium or by solution containing tetraethylammonium (10 mM), 4-aminopyridine (1.5 mM) or caesium (3 mM). Moreover, intracellular injection of ethyleneglycol-bis-(beta-aminoethylether)N,N-tetraacetic acid (EGTA) did not alter the hyperpolarization. On the other hand, barium (0.5 mM)-containing medium reduced the amplitude of the hyperpolarization by 20-40%. 5. Superfusion of ouabain (5-7 microM)-containing medium in normoxic conditions produced hyperpolarizing and depolarizing responses similar to those elicited by hypoxic exposure. The slow depolarization was also mimicked by elevation of the extracellular potassium concentration to 10-20 mM. 6. Evoked i.p.s.p.s were abolished within 4 min of hypoxic exposure while evoked e.p.s.p.s were maintained for about 20 min of hypoxic superfusion. Soma spikes of the neurones elicited by a depolarizing pulse were also well preserved. Their threshold was, however, raised, concomitant with a decrease in the peak amplitude. 7. When the slice was reoxygenated after 20-40 min of hypoxic exposure, the neurones immediately began to repolarize and showed a transient hyperpolarization of 5-10 mV in amplitude and 1-2 min in duration. The membrane potential, input resistance and action potential returned to the pre-hypoxic levels after 15-20 min of reoxygenation. The amplitude of the reoxygenation-induced hyperpolarization was not significantly changed when the membrane was hyperpolarized or depolarized. The hyperpolarization was eliminated by potassium-free medium or solution containing ouabain (1 microM).(ABSTRACT TRUNCATED AT 400 WORDS)

The development of mandibular molar tooth germs isografted in the mouse spleen

Tooth germs taken from 13-day-old embryonic mice and isografted in the spleen of adult mice were examined by light and electron microscopy. Well-organized tooth structures from the early cap stage to fully developed and mineralized mature teeth were obtained up to day 60 after transplantation. Germs on day 2 were similar to those prior to the onset of grafting but reached the late cap stage of development on day 4. On day 6, enamel and dentine formation were initiated and inner enamel epithelium and dental papilla cells were polarized. On days 10-15, enamel-matrix secretion was completed and almost all ameloblasts had become resorptive enamel epithelium. India ink injected from the recipient caudal vein accumulated to the capillaries within the pulp throughout the newly-formed vessels. On day 20, defined root formation had begun but occasionally irregular and cellular osteodentine was formed in root areas. On day 30, transplants were covered with reduced enamel epithelium and acellular cementum was formed at the root areas together with rudimentary periodontal ligament fibres. Cellular cementum became thicker up to day 40. There was little evidence of cellular infiltration from recipient tissue up to day 60. The spleen seems to be a suitable site for transplantation of tooth germs.

Opiate-antagonist reversal of neurological deficits--experimental and clinical studies

The proximal left M1 and the common trunk of A2 were clipped in 12 adult dogs. Naloxone was injected after placing the clips onto 6 dogs. Neither the systemic blood pressure nor the local cerebral blood flow were influenced by naloxone. In another group of 6 dogs with chronic right hemiplegia, naloxone proved passably effective in improving the hemiplegia. Eight patients with neurological deficits of various etiologies were administered levallorphan. The improvement in motor performance and/or elevation of mental activity was observed more or less in all but 2 of the patients. It was considered that the effect of opiate antagonists is based partially on the facilitation of synaptic transmission exaggerated by the arousal response.