An autoradiographic study of the renewal of mouse bronchiolar epithelium following bromobenzene exposure

We report an experimental model of germanium dioxide (GeO2)-induced neuropathy in rats. More than 6 months administration of GeO2 to young rats produced neuropathy characterized by segmental demyelination/remyelination and nerve edema. Electron microscopic studies demonstrated that changes in Schwann cells, such as an increased cytoplasmic volume or disintegration of the cytoplasm, were the earliest pathological findings. Schwann cell mitochondria contained high electron-dense materials. Subsequent removal of necrotic Schwann cell debris and myelin by invading macrophages was evident. These findings suggested that the Schwann cells themselves are the primary target of the toxin. The deposition of electron-dense granules in the intra-axonal vesicles, which was suggestive of glycogen granules in mitochondria, was observed in the advanced stage of the neuropathy. The findings of endoneurial edema with splitting of myelin lamellae were noted at the early stage of demyelination. Nerve edema may be the result of GeO2-induced endothelial cell injury.     

The action of cysteine of PHA-stimulation of lymphocytes. II. Influence on incorporation of 3H-uridine and 14C-leucine

The influence of short-term preincubation and continuous cultivation with L-cysteine hydrochloride on incorporation of 14C-leucine nad 3H-uridine in cultures of PHA-stimulated and unstimulated lymphocytes was studied. Preincubation during 1 and 2 hours in presence of cysteine inhibited incorporation of these compounds during the first few days of incubation. After 2-hr preincubation, incorporation was first somewhat depressed and then markedly enhanced. Continual presence of cysteine in the medium markedly inhibited incorporation of 3H-uridine and 14C-leucine from the first to last day of incubation.     

Dexamethasone treatment of the guinea pig fetus: its effects on the incorporation of 3H-thymidine into deoxyribonucleic acid

Pregnant guinea pigs of 50 to 53 days' gestation (term 63 days) were anesthetized with ether, and their fetuses were injected intramuscularly with 30 mg of dexamethasone or sterile saline. One week later, the fetuses were injected with 3H-thymidine intramuscularly under direct vision at laparotomy; after one hour, the incorporation of thymidine into deoxyribonucleic acid (DNA was analyzed in various fetal tissues. The relative labeling of DNA was significantly depressed in the cerebral hemispheres, cerebellum, medulla oblongata, and midbrain of the treated fetuses compared to their littermate controls. The relative labeling of the DNA of lungs, kidneys, heart, and adrenals was also significantly reduced. Increasing the dose of dexamethasone produced a progressive inhibition of the incorporation of 3H-thymidine into DNA. A variable recovery from the inhibition became apparent by 14 days following exposure to dexamethasone. The evidence suggests that exposure of the fetus to dexamethasone may exert a potentially deleterious effect on fetal tissues.     

Effects of handling and etherization on incorporation of [3H] lysine into protein of mouse brain and liver

An oxygen jet method ventilating patients during laryngoscopy has been applied to fiberoptic bronchoscopy. A 3.5 mm plastic tube 24.5 cm long was inserted into the trachea through the mouth. An intermittent jet of oxygen at 3.5 atm (50 psi) was applied to this tube using a 1.5 mm ID plastic catheter to ventilate the patient. Anesthesia was accomplished with intravenous thiamylal and Innovar. The patients were paralyzed with continuous succinylcholine. The technique has subsequently been used without complications in more than 1,000 patients. A fluidic ventilator was developed for delivering and controlling the oxygen jet. The airway pressure can be monitored continuously and, by the use of fluidic devices, the jet can be set to cut off automatically if the airway pressure is too high. The above techique for laryngoscopy with the fluidic ventilator was used in 28 patients undergoing fiberoptic bronchoscopy (Olympus 5.7 mm diameter). The airway pressure was continuously monitored with a line attached to the suction port of the bronchoscope. Arterial PCO2 ranged from 23 to 42 mmHg and PO2 from 105 to 325 mmHg. The high PO2 levels were maintained even during suctioning. General anesthesia for fiberoptic bronchoscopy can be performed using an endotracheal tube not smaller than 8 mm internal diameter (ID). The advantages of the oxygen jet technique are that it can be used in smaller patients and that the upper airway can be examined.     

Regulation of thrombospondin in the regenerating mouse facial motor nucleus

Thrombospondin (TSP) is a multifunctional extracellular matrix protein that plays a role in neuronal migration and axonal outgrowth in the developing central nervous system. In the current study we have examined the localization and regulation of TSP immunoreactivity (TSP-IR) during neuronal regeneration in the axotomized facial motor nucleus using Western blotting and light and electron microscopy. Transection of the facial nerve led to a gradual increase in TSP-IR in the regenerating motoneurons, peaking 4-7 days after injury (DAI). In addition to regenerating neurons, axotomy also caused a rapid upregulation of TSP-IR on activated microglia throughout the facial nucleus, with a maximum of 2-3 DAI, and a second increase at 14-21 DAI on microglial aggregates surrounding degenerating motoneurons and in neuronophagic microglia. In summary, injury leads to the induction of thrombospondin on axotomized neurons and activated microglia, peaking at the times of maximal posttraumatic microglial proliferation and during neuronal phagocytosis. Since thrombospondin is a multimodal extracellular matrix protein with a variety of cell attachment sites, thrombospondin might serve to link microglia and injured neurons, followed by microglial proliferation and removal of the neuronal debris.     

Decreased in vitro incorporation of 3H-thymidine into spleen cell DNA of antigenically stimulated rabbits treated in the postnatal period with nucleic acid from adult donors

This study investigates the long term or residual effects resulting from severe and extended exposure to stress. The samples were prisoners of war who were intended in Japan (high stress group) or Europe (low stress group) during the Second World War. They were examined in the following three areas: neuropsychological, psychiatric, and physical/neurological. Significant differences were found in all three spheres between the two groups. Second, to examine further the effect of length of internment on these variables, the low stress group was divided into long term and short term internment duration groups, and then the three groups were compared. Significant differences were found among these three groups. These results are discussed in relation to a traditional model of explanation.     

Magnetic resonance imaging of regenerating and dystrophic mouse muscle

Magnetic resonance imaging allows serial visualization of living muscle. Clinically magnetic resonance imaging would be the first step in selecting a region of interest for assessment of muscle disease state and treatment effects by magnetic resonance spectroscopy. In this study, magnetic resonance imaging was used to follow dystrophy and regeneration in the mdx mouse, a genetic homologue to human Duchenne muscular dystrophy. It was hypothesized that images would distinguish normal control from mdx muscle and that regenerating areas (spontaneous and after an imposed injury) would be evident and evolve over time. T2-weighted images of hind-limb muscles were obtained on anaesthetized mice in a horizontal bore 7.1-T experimental magnet. Magnetic resonance images of mdx muscle appeared heterogeneous in comparison to homogeneous images of control muscle. Foci of high intensity in mdx images corresponded to dystrophic lesions observed in the histologic sections of the same muscles. In addition, it was possible to follow chronologically the extent of injury and repair after an imposed crush injury to mdx muscle. These results should make it possible to obtain meaningful magnetic resonance spectra from particular regions of interest in muscle as viewed in magnetic resonance images (i.e., regenerating, degenerating, normal muscle) acquired during neuromuscular diseases and treatment regimens.     

An autoradiographic study on the localization of 131I-labeled thyroid hormones in the tissues of the pig

Autoradiographic studies on the localization of 131I-labeled thyroxine and triiodothyronine in the various organs and tissues of the pig have been conducted. The isotopes were compared as to the intensity of radioactivity on the basis of the concentration of developed silver grains in the tissues following the respective radioactive hormone injections. In general, for an identical dose of the isotope and with analogous processing procedures, the autoradiographs of most of the tissues after triiodothyronine were relatively more radioactive than after thyroxine. In both the hormone treatments, the tissues from younger pigs were relatively more radioactive than the tissues of older pigs. The various tissormones. Based on differential localization of radioactivity, the pigs excreted more radioiodine through bile, pancreatic and salivary secretions and in urine.     

Kinetic analysis of ATP-synthetase and ATPase in regenerating rabbit liver

The activities of ATP-synthetase and ATPase in rabbit liver were evaluated by kinetic analysis of rapid changes in ATP during alteration of oxygen supply, and were compared between normal and hepatectomized rabbits. Velocity constants of ATP-synthetase and ATPase were computed on the assumption that ATP-synthetase and ATPase follow the pseudo-first order reaction of ADP and ATP, respectively. The velocity constant of ATPase increased from the control value of 0.21 to 0.48 (min-1) in the remnant rabbit liver at 24 h after 70% hepatectomy. The velocity constant of ATP-synthetase increased from the control value of 4.05 to 5.24 (min-1) after the hepatectomy. These results indicate that both ATP-synthetase and ATPase are accelerated due to liver regeneration.     

3H]Neurotensin receptor densities in human postmortem brain tissue obtained from normal and schizophrenic persons. An autoradiographic study

[3H]Neurotensin binding and autoradiographic techniques were used to determine the distribution and density of neurotensin receptors in normal and schizophrenic postmortem brain tissue. Coronal hemi-brain blocks of tissue were cut at the level of the caudate and hippocampus from frozen brain tissue obtained from normal individuals with no known psychiatric or neurologic illnesses and from schizophrenic subjects off- or on-antipsychotic drugs at the time of death. Each hemi-block was further divided, sectioned, thaw mounted on to slides, incubated with [3H]neurotensin and apposed to film. Digitized images were analyzed for binding densities. Areas of intense binding include the substantia nigra, the entorhinal cortex, superficial layers of the cingulate, middle frontal, and insular cortices; and with moderate binding in nucleus accumbens, and caudate. Schizophrenic patients off- (3 months or more) or on-antipsychotic drugs at the time of death were tested; all patients showed a reduced level of neurotensin receptors in the caudate (68% of normals), cingulate (34%) and prefrontal cortices (25%).     

Renewal of DNA in Purkinje cell nuclei of mouse cerebellum. A 9-month follow-up autoradiographic study

3H thymidine was injected into pregnant mice in order to label the DNA in the dividing Purkinje cell (PC) precursors of the embryonic cerebellum. The retention of 3H-DNA was evaluated in PC nuclei of animals at the age of 25 days, 3, 6 or 9 months by light microscope autoradiography. The number of silver grains decreased in the whole nuclei by 13.6% and 19.6% in animals 6- and 9-month-old, respectively. In the nucleolar region, the loss of DNA radioactivity was more profound; the silver grain counts decreased by 22.6% and 29.1% in 6- and 9-month-old animals, respectively. No significant differences in the volume and dry mass concentration were found in the PC nuclei of 25 PD and 9 PM old animals. Therefore, the observed changes in grain density counts represent the actual measure of 3H-DNA loss, and/or "spontaneous" renewal of the DNA molecule in PC nuclei, as well as its higher expression in the nucleolar region. Furthermore, it follows from the comparison of our data with those present in the literature, that DNA synthesized in nerve cell precursors before their withdrawal from the mitotic cycle is more stable than that synthesized in postmitotic neurones. This suggests that the repair of DNA in mature neurones might be of an error-prone type.     

An autoradiographic study of the development of the entorhinal and commissural afferents to the dentate gyrus of the rat

The development of the entorhinal, ipsilateral associational, and commissural afferents to the dentate gyrus have been studied autoradiographically, following the injection of small amounts of tritiated proline into the medial and lateral parts of the entorhinal cortex, and into fields CA3c and CA4 of the hippocampus, in a series of rats, on the third, sixth, and twelfth postnatal days. Clear labeling of the entorhinal afferents were found at the third postnatal day, and from the earliest stage studied the afferents from the two parts of the entorhinal cortex appear to be spatially segregated within the stratum moleculare of the dentate gyrus: the fibers from the lateral entorhinal area occupying the outermost one-third, or so, of this stratum, while those from the medial entorhinal cortex occupy its middle zone. The ipsilateral hippocampo-dentate associational pathway is present at the third postnatal day, but the commissural projection (which shares with it the inner part of the stratum moleculare) could not be labeled until the sixth postnatal day. By the twelfth day the characteristic adult pattern of distribution of the terminals of the two hippocampo-dentate pathways is established. Although this pattern is best accounted for on the basis of a temporal competition for the available synaptic sites on the proximal parts of the dendrites of the granule cells, the spatial segregation of these two fiber systems from those arising in the entorhinal cortex, is probably due to the selective fasciculation of fibers in each group of afferents and to their early cytochemical specificity.     

Neurosteroid modulation of [3H]flunitrazepam binding in the medulla: an autoradiographic study

Neurosteroids bind to unique sites on the GABA(A) receptor complex and modulate receptor function. The effects of neurosteroids on GABA(A) receptors have been well characterized in forebrain regions. However, little is known about their effects on GABA(A) receptors in the medulla, especially those areas involved in autonomic reflex pathways. Stimulation of [3H]flunitrazepam binding to the GABA(A) receptor by two progesterone metabolites, 3alpha-hydroxy-5alpha-pregnan-20-one (3alpha-OH-DHP) and 3beta-hydroxy-5alpha-pregnan-20-one (3beta-OH-DHP), was studied using autoradiographic methods in the medulla and cerebellum of female rats at estrus. [3H]Flunitrazepam binding was enhanced by 3alpha-OH-DHP in every nucleus examined in the medulla and cerebellum. This effect was stereoselective since 3beta-OH-DHP had no effect on binding in any region. No differences were observed in the degree of stimulation of [3H]flunitrazepam binding by 3alpha-OH-DHP among medullary brain regions. However, in the cerebellum, the stimulation of binding was significantly greater in the granular layer than in the molecular layer. Stimulation of [3H]flunitrazepam binding by 3alpha-OH-DHP in nuclei involved in the baroreflex pathways supports previous studies which report that neurosteroids modulate autonomic regulation of blood pressure. These actions may also underlie alterations in autonomic function during pregnancy.     

Aspects of 1,25-dihydroxyvitamin D3 binding sites in fish: an autoradiographic study

The distribution of specific binding sites for vitamin D3 in adult female and male Xiphophorus helleri is studies after injection of tritiated 1,25-dihydroxyvitamin D3 (vitamin D) by thaw-mount autoradiography. Five hours after injection of labeled vitamin D specific nuclear binding is present in brain, pituitary, skin, gills, cartilage, gut, liver, pancreas, spleen, kidney, muscle, ovary, and testis. Cytoplasmic binding exists strongest in gills, gut, and kidney while it is comparatively weak in hepatocytes. In reproductive organs cytoplasmic retention of radioactivity is also present in oocytes. Weak nuclear labeling exists in interstitial cells in ovary. Conspicuous nuclear labeling exists in active lobules of testis, while inactive lobules show occasionally a few labeled cells. The results demonstrate specific binding and retention of vitamin D in many target organs of teleost fish, suggesting an extensive and multifunctional regulatory role of this steroid hormone of sunlight.     

Manipulation of metallothionein expression in the regenerating rat liver using antisense oligonucleotides

In order to gain some insight into the fate of fumarate synthesised in the cytosol in the purine nucleotide cycle and in amino acid catabolism, the capability of both rat kidney mitochondria and acidotic rat kidney mitochondria to take up either externally synthesised, via adenylsuccinate lyase, or added fumarate in exchange with intramitochondrial malate or aspartate was tested by means of both spectrophotometric and isotopic techniques. The appearance of either malate or aspartate caused by the presence of fumarate was revealed outside normal and acidotic mitochondria by using specific substrate detecting systems. Consistently, externally added fumarate was found to cause efflux of either [14C]-malate or [14C]-aspartate from loaded mitochondria. The occurrence in rat kidney mitochondria of two separate translocators, i.e., fumarate/malate and fumarate/aspartate carriers, is shown in the light of saturation kinetics and the different inhibitor sensitivity. The fumarate/aspartate antiporters found in normal and acidotic mitochondria appear to differ from each other.