Effects of entorhinal lesions on trophic activities present in rat entorhinal cortex and hippocampus as studied using primary cultures of entorhinal and septal tissues

The present study examined trophic activities in normal and injured brain which affect the survival and growth of central neurons in culture. Adult rats received bilateral lesions through the angular bundle, severing projections between the entorhinal cortex and the hippocampus. Ten days later, extracts were prepared from the entorhinal or hippocampal regions of the injured brains and compared with extract prepared from analogous regions of normal brains for trophic activities in cultures of either entorhinal or septal tissues. At least three activities were observed: (1) a trophic activity which bound to polylysine-treated wells, which was greater than 10,000 Da in size, heat labile, and sensitive to trypsin, and which supported the survival of both septal and entorhinal neurons in culture; (2) a trophic activity which did not bind to polylysine-treated wells, which was greater than 10,000 Da in size, heat labile, and sensitive to trypsin, and which, in the presence of polylysine-bindable material, facilitated the survival and growth of entorhinal cells in culture, and (3) an inhibitory activity which significantly reduced survival in entorhinal cultures when cells were plated in the presence of high concentrations of extract prepared from normal brain. These effects were not due to nonspecific effects of plating the cells in, or treating the wells with, large amounts of protein. A significant injury-related increase in non-polylysine-bindable trophic activity was also observed. Extracts prepared from either the hippocampus or the entorhinal area of the injured brains contained more non-polylysine-bindable trophic activity than extract prepared from normal brains. Injury-related changes in trophic activities were more prominent in entorhinal than in septal cultures. This increase in activity may account for the injury-related effects on the survival of entorhinal transplants reported previously [Gibbs and Cotman: Neuroscience (in press) 1987], and may represent an endogenous mechanism by which the brain attempts to selectively support the survival of injured cells following injury.

Static magnetic field influence on rat tail nerve function

Motor nerve conduction and excitability were measured on the tail nerve of anesthetized rats before and after the nerve was exposed perpendicularly to a static electromagnetic field of various intensities and durations. There was no significant change in either the distal latencies or the amplitudes of the compound muscle action potential (CMAP) measured from stimulating the tail nerve after it was exposed to the electromagnetic field with a density up to 1.2 Tesla (T) for a duration of 60 seconds. However, the nerve excitability expressed as changes of the amplitudes of the submaximally evoked CMAP increased significantly when the tail nerve was exposed to a magnetic field with a density higher than 0.5T for more than 30 seconds. The finding that an electromagnetic field increases motor nerve excitability suggests a possible mechanism of its therapeutic effects.

The neuroanatomy of mental retardation in the white rat

A provisional examination of a set of questions pertaining to the neuroanatomical basis of mental retardation was undertaken by assessing the learning ability of 25 different groups of young rats prepared with various cortical and subcortical lesions. The test battery included a visual discrimination, a nonvisual discrimination, a three-cul maze and three separate detour problems. Seven of the 25 groups were impaired in learning all problems (suggestive of a generalized learning impairment) and therefore were viewed as being mentally retarded. One of these groups suffered diffuse multifocal neocortical damage, while the lesions in the remaining six were located either within the parietal cortex, globus pallidus, ventrolateral thalamus, substantia nigra, median raphe or pontine reticular formation. Based upon a variety of observations, it is proposed that the generalized learning impairment seen in our brain-damaged rats, rather than being reducible to a sensory, motor, arousal-motivational-emotional, attentional, inhibitory or recent memory defect, is the product of a defect in "executive" processes.

Comparison of Doppler and strain-gauge plethysmography to detect vasculogenic impotence

Doppler penile-pressure determinations to diagnose vasculogenic impotence require an experienced technician, can be time-consuming, yield inconsistent results and require much penile manipulation. Therefore the authors assessed and compared strain-gauge plethysmography as an alternative noninvasive procedure. Sixty-one patients with erectile failure had penile blood pressure determined by Doppler and indium-gallium alloy in Silastic strain-gauge plethysmography. Penile brachial indices were calculated. Strain-gauge results agreed with the Doppler measurements in all but three patients whose indices were found to be normal by Doppler and borderline by strain-gauge plethysmography. The sensitivity, accuracy and specificity of strain-gauge plethysmography were 93%, 95% and 100% respectively. Doppler determinations required an average of 20 minutes to perform, strain-gauge measurements only 4. The authors conclude from this study that strain-gauge plethysmography is a rapid, reliable, accurate method of determining penile blood pressures.

Anomalous clustering of underglycosylated band 3 in erythrocytes and their precursor cells in congenital dyserythropoietic anemia type II

Congenital dyserythropoietic anemia type II (CDA II or HEMPAS) is a genetic anemia caused by membrane abnormality. Our previous studies indicated that in HEMPAS, erythrocytes band 3 and band 4.5 are not glycosylated by polylactosaminoglycans. The present study was aimed at determining how such underglycosylated band 3 behaves in erythrocyte membranes. By using anti-band 3 antibodies, immunogold electron microscopy revealed that band 3s are clustered in HEMPAS erythrocyte membranes. By freeze-fracture electron microscopy, band 3s were also seen as lightly clumped intramembrane particles on a protoplasmic fracture face. Erythrocyte precursor cells stained by anti-band 3 antibodies showed that band 3s are present in the cytoplasmic area of the reticulocytes as scattered single particles. However, in young erythrocytes in which intracellular membranes are almost degenerated, band 3s were clustered in the cytoplasmic area of the cell. These observations suggest that band 3s cluster before they are incorporated into the plasma membranes of HEMPAS erythrocytes. In contrast to band 3, glycophorin A detected by anti-glycophorin A antibodies did not show a noticeable difference between normal and HEMPAS. Such a clustering of band 3 may cause abnormal localization of band 3-associated proteins and may thus result in the macroscopic membrane abnormality seen in HEMPAS erythrocytes.

ADR1-mediated regulation of ADH2 requires an inverted repeat sequence

DNA sequence analysis of wild-type and mutant ADH2 loci suggested that two unusual features 5' of the promoter, a 22-base-pair perfect dyad sequence and a (dA)20 tract, were important for regulation of this gene (D. W. Russell, M. Smith, D. Cox, V. M. Williamson, and E. T. Young, Nature [London] 304:652-654, 1983). Oligonucleotide-directed mutagenesis was used to construct ADH2 genes lacking the 22-base-pair dyad or the (dA)20 tract (V.-L. Chan and M. Smith, Nucleic Acids Res. 12:2407-2419, 1984). These mutant genes and other ADH2 deletions constructed by BAL 31 endonuclease digestion were studied after replacing the wild-type chromosomal locus with the altered alleles by the technique of gene transplacement (T. L. Orr-Weaver, J. W. Szostak, and R. S. Rothstein, Proc. Natl. Acad. Sci. USA 78:6354-6358, 1981), using canavanine resistance as the selectable marker. Deletions lacking the dyad failed to derepress normally and did not respond to mutations at the ADR1 locus, which encodes a protein necessary to activate ADH2. Deletions of the (dA)20 tract did not have a detectable phenotype. A small deletion located just 3' to the (dA)20 tract (between positions -164 and -146) had a low amount of ADR1-dependent transcription during repressed growth conditions, indicating that the regulatory protein encoded by ADR1 is present in a potentially active form during repression and that alterations of a DNA sequence in the promoter region can unmask its latent activity.

Neurotrophic activity in the central and peripheral nervous systems of the cat. Effects of injury

Neurotrophic activity for ciliary ganglion neurons in culture was found in both central and peripheral nervous system of the cat. The activity found in extracts of spinal cord supported the survival of 100% of the test neurons during 24 h and was characterized by a slope of -56 +/- 13 in the linear portion of the dose-response curve. Sciatic nerve extract supported the survival of only 60% of the test neurons; it dose-response curve had a slope of -20 +/- 4. Extracts of meninges, spinal rootlets, dorsal root ganglia and muscle supported 100% of the test neurons; two slopes were observed in their dose-response curves, which coincided with those of spinal cord and sciatic nerve dose-response curves. The two different slopes may correspond to two different active molecules, tentatively denominated I and II, having distinct distributions in the assayed tissues. In the spinal cord, both direct injury and deafferentation led to increases in neurotropic activity. In the peripheral nervous system, transections leading to death of dorsal root ganglion neurons or to degeneration of their axons were accompanied by decreases in activity II. Activity I in dorsal roots and dorsal root ganglia was unaffected by injury and may be associated with non-neuronal cells or extracellular matrix components.

Background activity in pulmonary vagal C-fibers and its effects on breathing

Vagal cooling experiments suggest that the deep slow breathing observed after vagotomy results not only from loss of pulmonary stretch receptor feedback, but also from loss of some unidentified vagal input. To investigate this possibility we cooled the vagus nerves in anesthetized dogs. In dogs breathing spontaneously, the Hering-Breuer reflex was abolished at 7 degrees C, but average expiratory time was unchanged and lengthened only on cooling below 3 degrees C. In artificially ventilated dogs the pulmonary vagus nerves were cooled in the chest and phrenic activity was recorded. Entrainment of phrenic bursts to the ventilator cycle ceased at 7 degrees C, and expiratory pauses shortened; they lengthened again on cooling below 3 degrees C. Cervical vagotomy did not change breathing pattern after the pulmonary vagus nerves were cut. Recording of afferent impulses during cooling showed that at 5 degrees C or less pulmonary vagal input was confined largely to nonmyelinated fibers; at 3 degrees C, background activity in pulmonary C-fibers was still 78% of control whereas myelinated afferents were virtually silent. We suggest that in eupnea low frequency, background activity in pulmonary afferent C-fibers shortens expiratory time.

Lack of correlation between cortical levels of choline acetyltransferase and learning scores in rats with globus pallidus lesions

Previous work has shown that rats with lesions of the globus pallidus (GP) exhibit a generalized learning impairment. Data are presented suggesting that this impairment is not due to inadvertent damage to the nucleus basalis magnocellularis. Rats with GP lesions evidenced a significant visual discrimination learning loss and a significant reduction in cortical choline acetyltransferase (ChAT) activity. However, there was no significant correlation between the severity of the learning loss and the amount of reduction of cortical ChAT activity.

Learning deficits in rats with early neurotoxic lesions to the globus pallidus, substantia nigra, median raphe or pontine reticular formation

Previous studies have shown that weanling rats with electrolytic lesions of the globus pallidus (GP), substantia nigra (SN), median raphe (MR) or pontine reticular formation (PRF) are deficient in learning a wide variety of laboratory tasks. The current study was designed to investigate whether this nonspecific learning deficiency is due to destruction of cells intrinsic to these subcortical regions or to fibers passing through these regions. Accordingly, neurotoxic lesions of the GP, SN, MR or PRF were made in weanling rats using ibotenic acid. Rats were subsequently required to learn a visual discrimination, a 3-cul maze and a nonvisual (incline plane) discrimination. While those groups with GP, SN or MR lesions showed significant deficits on all three problems, only the animals with GP lesions exhibited deficits comparable in magnitude to those associated with corresponding electrolytic lesions. Animals with lesions to the PRF were impaired only on the nonvisual discrimination. These results suggest that while destruction of neurons alone within the GP, SN or MR can produce a nonspecific learning impairment, the combined destruction of neurons and fibers of passage within the SN, MR or PRF produces a more profound learning deficit.

Deficits in response inhibition and attention in rats rendered mentally retarded by early subcortical brain damage

Young rats with lesions to either the globus pallidus, substantia nigra, median raphe, or pontine reticular formation have previously been reported to be deficient in learning a wide variety of laboratory tasks. In the current study, weanling rats subjected to one of these lesions were rested for three weeks, then examined for acquisition and extinction of a water-motivated straight alley task, and finally tested on luminous flux discriminations of increasing difficulty. All brain-damaged groups were slower than the controls in extinguishing the alley task and only the median raphe group failed to show an impairment on the discrimination problems. These results and others suggest that the foregoing lesions produce deficits in inhibitory and attentional processes. The possibility is discussed that young rats bearing these lesions might serve as a model for the investigation of the neurobiological and cognitive disturbances underlying certain classes of mental retardation in children.

Effects of thoracic spinal cord transection on colonic motor activity in rats

The resting colonic motor activity before and consecutively after spinal cord transection was recorded in male Sprague-Dawley rats. Recording probes were anchored surgically in the ascending and descending colon. Pressure changes were recorded on a dynograph using a low compliance perfusion system. A motility index took into account the amplitude, duration and frequency of contractions. Following a baseline recording animals were subjected either to spinal cord transection at T4 level or a sham operation. The recording sessions continued regularly on alternate days for the observation period of 3 weeks. Transection of the thoracic spinal cord markedly reduced the motility index of the distal colon on the first postoperative day. However, the motor activity gradually returned to pre-operative values after 7 days. Sham surgery did not influence the motor activity. These findings suggest that colonic motor activity is influenced by spinal shock and probably by different neural mechanisms mediating proximal and distal activities of the colon in rats.

The comparative effects of frontal, parietal, occipitotemporal, and limbic forebrain lesions in weanling rats on learning

Young rats prepared with discrete bilateral lesions to the cerebral cortex, cingulate cortex, or dorsal hippocampus were required to learn a white-black discrimination, a 3-cul maze, and a nonvisual inclined plane discrimination. Only those rats with parietal lesions were impaired in acquiring all three habits. Those with occipitotemporal, frontocingulate, or posterior cingulate lesions were impaired on two habits, those with dorsal hippocampal lesions were impaired on one habit, and those with frontal (motor) cortical lesions failed to show any impairment. These results coupled with others suggest that the parietal cortex is unsurpassed in the wide range of learning and retention deficits which follows restricted neopallial lesions.

Sequential alterations in globin gene chromatin structure during erythroleukemia cell differentiation

During differentiation of murine erythroleukemia cells, adult beta-globin gene chromatin acquires site-specific, DNase I hypersensitivity and an increased sensitivity in the globin gene region toward micrococcal nuclease (MNase) digestion. The relationship of these changes in chromatin structure to globin gene activation and to cellular commitment events has been studied. Imidazole, which blocks globin gene transcription during induction does not affect the terminal differentiation of the cells nor does it prevent the acquisition of DNAse I hypersensitivity. The formation of the inducible DNase I-hypersensitive site near the globin gene accompanies the developmental events which lead to cellular differentiation independent of the transcription process. The increased MNase sensitivity of the adult beta-globin gene region, normally preceded by the acquisition of 5' DNase I hypersensitivity, was blocked by the addition of imidazole prior to but not after globin gene activation. The enhanced MNase sensitivity was not abolished by the addition of actinomycin D and, thus, reflects a part of chromatin alterations that define potential for transcription. Therefore, there is a sequential series of chromatin alterations in the globin gene region associated with murine erythroleukemia cell differentiation. The appearance of the inducible 5' DNase I-hypersensitive site precedes the onset of globin gene transcription and is strongly correlated with commitment events. The enhanced MNase sensitivity is closely related to globin gene transcription, but it is not a consequence of the transcription process. In addition, the commitment of cells to terminal differentiation is dissociable from the stimulation of globin gene transcription.

Morphological changes in leukemic lymphoblasts and normal lymphocytes treated with deoxyadenosine plus deoxycoformycin

It remains unclear how lympholysis occurs in children with an inherited deficiency of adenosine deaminase (ADA) and in leukemic patients undergoing treatment with an inhibitor of ADA, deoxycoformycin. Adenosine deaminase deficiency with subsequent lympholysis can be simulated in vitro by treatment of lymphoid cells with deoxyadenosine plus deoxycoformycin. We found that such in vitro treatment caused fragmentation of the nucleus, disintegration of nuclear chromatin, and the formation of cytoplasmic blebs in T-lymphoblast lines, but not in B-lymphoblast lines. For all but one of the cell lines tested, the extent of morphological changes paralleled the sensitivity to growth inhibition by deoxyadenosine plus deoxycoformycin. Similar morphological changes were observed in normal peripheral blood lymphocytes treated with deoxyadenosine plus deoxycoformycin. These morphological changes were energy-dependent processes. They were preceded by inhibition of DNA synthesis and deoxyadenosine triphosphate (dATP) accumulation, but followed by depletion of adenosine triphosphate (ATP) and cell lysis. These changes may represent an intermediate step between metabolic alterations and lympholysis.

A method for analyzing transcription using permeabilized cells

Brief exposure of Friend cells to a buffered hypotonic solution containing 1% Tween 80 caused permeabilization and allowed incorporation of [3H]UTP into RNA. The incorporation was inhibited 85-97% by 20 micrograms/ml actinomycin D and the reaction product was completely hydrolyzed by 0.1 M KOH. UMP incorporation was nearly linear for 60 min at 23 degrees C; however, at 37 degrees C it ceased after 15-20 min of rapid incorporation. The inhibition of UMP incorporation by 2 micrograms/ml alpha-amanitin was much greater at 23 degrees C than at 37 degrees C. The molecular weight of the RNA synthesized in permeabilized cells is broadly distributed with about 83% larger than 18 S. In vitro transcription of the mouse beta-major globin gene was studied by hybridizing 32P-labeled nascent RNA to filter-bound DNA sequences representing this gene and its flanking regions. After induction by hexamethylene-bisacetamide, Friend cells exhibited more than fivefold increases in the rate of transcription for the beta-major globin gene as compared to the uninduced control cells. Induction also caused an increase in the transcription rate of the 3'-flanking region located downstream from the poly(A) addition site. Thus, the primary transcription unit of beta-major globin gene is essentially the same in permeabilized cells as that previously reported for nuclei isolated from the same cell line. In addition, permeabilized cells actively initiate RNA synthesis as determined by the incorporation of a thiol group at the 5' initiating nucleotide, when synthesis was in the presence of [gamma-S]-labeled nucleoside triphosphates. Permeabilized cells are about 7-11 times more active than isolated nuclei in the synthesis of both in vitro-initiated and total RNA.

Chemotherapy of small-cell carcinoma of lung: a randomized comparison of alternating and sequential combination chemotherapy programs

One hundred forty-seven eligible patients with small-cell carcinoma of the lung (SCCL) have been randomized to receive alternating (A) or sequential (S) combination chemotherapy. Initial treatment was with three cycles of VAM (A) or two cycles of POCC (S). VAM consists of VP16-213 200 mg/m2 intravenously (IV) day 1, Adriamycin (Adria Laboratories, Columbus, Ohio) 50 mg/m2 IV day 1, and methotrexate 30 mg/m2 IV day 1 repeated at 21-day intervals. POCC consists of cyclophosphamide 600 mg/m2 IV days 1 and 8, vincristine 1.5 mg/m2 (maximum, 2 mg) IV days 1 and 8, CCNU 60 mg/m2 po day 1, and procarbazine 100 mg/m2 po days 2 through 15. After initial treatment, all patients received whole brain radiation therapy (3,000 rad/10 fractions/2 wk). Patients with limited disease in addition received irradiation encompassing the tumor, hilar, mediastinal, and supraclavicular regions (5,000 rad/25 fractions/5 wk). After radiation, patients on arm A received POCC alternating with VAM; patients on arm S received POCC until progression when they were to be treated with VAM. The alternating arm was superior with respect to rate of complete remission (CR), median disease-free survival (MDFS), and median survival (MS). The advantage of alternating therapy was not as clearly demonstrated in the limited disease groups when interposition of involved field radiation delayed the initiation of the alternating schedule. In limited disease alone, comparing arm A with arm S, no statistically significant differences were noted. The CR rate was 42% v 54%, MDFS was 14 v 10 months, and MS was 16 v 10 months. In extensive disease, the CR rate was 44% v 20% (P = .03), MDFS was 6 v 4 months (P = .003), and MS was 10 v 7 months (P = .001). Improved treatment outcome in SCCL is achieved when combination chemotherapy regimens of similar effectiveness are administered in an alternating rather than sequential schedule.

beta-Globin gene family in murine erythroleukemia cells resides within two chromatin domains differing in higher order structure

The beta-globin gene family is organized into two distinct chromatin domains which are digested at significantly different rates by DNase I. We have investigated the possibility that this differential DNase I sensitivity is based upon differences in the higher order structure of chromatin. When nuclei are digested under low ionic strength conditions known to unfold higher order chromatin structures, the differential sensitivity is lost. That is, the relatively DNase I resistant domain, containing the transcriptionally inactive embryonic and beta-homologous globin genes, becomes sensitive. When chromatin is recondensed with either MgCl2 or NaCl, thus indicating the higher order coiling of the chromatin fiber, the differential sensitivity is restored. Furthermore, the removal of histone H1, known to be essential for stabilization of higher order chromatin structures, results in the loss of differential DNase I sensitivity. In contrast to the DNase I resistant domain, the transcriptionally active adult beta-globin genes show no increase in the rate of digestion when chromatin is unfolded, indicating that this domain may exist as an unfolded nucleosomal chain. The data further suggest that this sensitive domain may be depleted of histone H1.

Accumulation of a heat shock-like protein during differentiation of human erythroid cell line K562

The human erythroid cell line K562 provides a model system for studying erythroid differentiation and eukaryotic gene regulation. These cells express glycophorin A, spectrin and i antigen. They accumulate embryonic and fetal haemoglobins on induction of erythroid differentiation with haemin, sodium butyrate or hydroxyurea. In the present study, the protein composition of K562 cells during haemin-mediated induction of erythroid maturation was analysed by two-dimensional gel electrophoresis. Under conditions in which haemin did not effect cell viability and proliferation, a protein of approximately 70,000 molecular weight (MW) accumulated in the differentiated K562 cells. The accumulation appears to be due to an increase in the rate of RNA synthesis for this protein. The protein is related in sequence to a 70,000-MW heat shock protein. An antigenically related protein was also demonstrated in human bone marrow and accumulates at particular stages of human erythroid maturation.

Induction of spinal seizures by natural stimulation in cats

Transection of the spinal cord of the cat at a thoracic or lumbar level results, after as short a period as 12 days, in a preparation with such altered excitability that repeated natural stimulation of the dermatome just caudal to the transection site will induce, in as short a time as 3 days, seizure discharges. The trigger zone for the seizure spreads to caudal dermatomes when these caudal regions are repeatedly stimulated. The 'typical' T4-T7 seizure is a scratch reflex followed by the tonic-clonic seizure lasting for 20-30 s and ending with a scratch afterdischarge lasting for several minutes. Lower thoracic and upper lumbar seizures consist of tonic-clonic co-contractions of the muscles of the hindlegs, followed by rhythmical stepping movements lasting less than 1 min. Partial dorsal rhizotomy or local Cobalt application to the spinal cord may reduce the threshold for induction of seizure by natural stimulation and local Penicillin application to spinal cord induces seizure discharges similar to those induced by natural stimulation. Retransection of the spinal cord caudally, with elimination of the primary trigger zone, does not abolish the secondarily acquired triggers. The findings suggest that spinal circuits possess the ability to acquire new neuronal patterns of discharge and to transfer them to other more caudal segments.

Cortical mechanisms underlying acquisition of latch-box problems in the white rat

Adult rats, previously subjected to bilateral frontal, parietal, occipital, frontocingulate or posterior cingulate ablations, were required to learn two discrete latch-box tasks (sliding a barrel-bolt to the right and elevating a hook). Those groups showing significant learning impairments had lesions to either the frontal cortex or frontocingulate cortex. The data suggest that the neocortical focus for latch-box deficits lies rostral to Level 8 on the Lashley brain diagram, while the frontocingulate focus for latch-box deficits lies within the prelimbic area.

Alterations in globin gene chromatin conformation during murine erythroleukemia cell differentiation

Adult beta-globin gene chromatin in murine erythroleukemia (MEL) cells acquired increased sensitivity to both micrococcal nuclease and DNase I during hexamethylenebisacetamide-induced erythoid differentiation. The DNase I hypersensitivity of the globin genes accompanied their actual transcription and was strongly correlated with commitment events. On the other hand, the rate of micrococcal nuclease digestion was closely related to the rate of globin gene transcription. Two distinct DNase I hypersensitive sites were found on the 5' side of the beta-major globin gene in HMBA-induced cells. One site was located near the 5' side of the beta-major globin gene and the second site was located approximately 3 kilobases upstream of the beta-major cap site. Following the commitment of MEL cells to differentiate, DNase I sensitivity was stably inherited in the absence of inducer. In contrast to HMBA, another inducer, hemin, known to cause the accumulation of globin-specific mRNA in MEL cells by a post-transcriptional mechanism, did not elicit alterations of beta-globin gene chromatin. The addition of dexamethasone, a hormone known to inhibit MEL cell commitment, blocked the formation of general and site-specific nuclease sensitivity of beta-globin gene chromatin prior to but not after cell commitment.

Chromatin structure of the beta-globin gene family in murine erythroleukemia cells

We have analyzed the chromatin structure of the beta-major globin gene and other related beta-globin genes in induced and uninduced murine erythroleukemia (MEL) cell nuclei. Nuclei were digested with either DNase I or micrococcal nuclease, and the purified DNA was hybridized to a set of cloned genomic DNA fragments covering the beta-globin gene region. This region consisted of two distinct domains as characterized by sensitivity to DNase I digestion. One domain was relatively sensitive and contained the potentially active or actively transcribed beta-major and beta-minor globin genes. The other, relatively insensitive domain contained the nontranscribed embryonic and beta-globin homologous genes. The sensitivity of these domains was not altered during erythroid differentiation. In nonerythroid cells, the entire globin gene family, including the adult and embryonic globin genes, was contained in a single relatively resistant domain. Micrococcal nuclease (MNase) also defined two general domains of nuclease sensitivity that coincided with those of DNase I. However, the relatively sensitive MNase domain containing the beta-major and beta-minor genes became more sensitive upon chemically stimulated erythroid differentiation. A detailed examination of the beta-major globin gene revealed that the actual coding region became increasingly sensitive to micrococcal nuclease after differentiation while the 5'-flanking DNA did not. Thus, micrococcal nuclease was able to accurately define the primary transcription unit of the beta-major gene.

Maternal hyperphenylalaninemia fetal effects

Thirty-four children of 11 mothers with untreated hyperphenylalaninemia had a pattern of malformation consisting of prenatal and postnatal growth retardation, microcephaly and central nervous system dysfunction, increased incidence of malformations, and a peculiar facial appearance. Maternal hyperphenylalaninemia appears to be teratogenic, with a variability related to the blood phenylalanine concentration.

Reorganization of cerebral control of tactile placing after interrupting a spinal ascending system in cats with pyramid section

Interruption of a spinal ascending system by hemisection of the spinal cord at mid-thoracic level restores the tactile placing (TP) which is lost after bulbar pyramid section in cats. To determine the location of the ascending system in the spinal cord, partial lesions involving various dorsal, lateral, or ventral tracts were made at mid-thoracic level in cats with pyramid section. To determine the supraspinal control of the recovered TP after pyramid section and spinal cord hemisection, lesions were made in other cortical and subcortical structures essential to TP and also in cortical areas which are not normally involved in TP in cats with recovered TP. The findings demonstrate that the spinal ascending system is located in the ventral part of the lateral funiculus and that the cerebral association cortex takes over the function of motor cortex in the reorganized control of TP. A slow course of TP recovery along with no recovery of impaired distal forelimb movements resulting from pyramidotomy were also observed.

A generalized learning deficit in albino rats with early median raphe or pontine reticular formation lesions

Recent studies suggest that lesions of the median raphe or pontine reticular formation in adult rats are associated with a nonspecific (generalized) learning impairment. The present study showed that lesions in the region of the median raphe or pontine reticular formation in 21 day old rats likewise produced a nonspecific learning impairment, as evidence by significant deficits on a visual discrimination, nonvisual incline plane discrimination, 3-cul maze, and three simple spatial problems. The finding that relatively large lateral pontomesencephalic lesions did not lead to deficient learning of any of these tasks indicates that lesion locus rather than lesion size is responsible for the production of the learning deficits observed in this study.

Dihydropteridine reductase deficiency: non-response to oral tetrahydrobiopterin load test

In a child with dihydropteridine reductase deficiency (McKusick 26163) none of four separate oral tetrahydrobiopterin loading tests resulted in a decrease of the serum phenylalanine concentration. This test cannot be recommended for screening hyperphenylalaninaemic patients for dihydropteridine reductase deficiency.

Inhibition of RNA synthesis by deoxyadenosine plus deoxycoformycin in resting lymphocytes

Deoxyadenosine has been implicated in the lymphocytopenia that occurs in immunodeficient children with an inherited deficiency of adenosine deaminase (ADA) and in leukemic patients treated with the ADA inhibitor deoxycoformycin. The recent reports of deoxyadenosine toxicity to nondividing lymphocytes indicates a challenge to the mechanism for deoxyadenosine toxicity, which involves the inhibition of ribonucleotide reductase by dATP, leading to the inhibition of DNA synthesis. This study provides evidence for the inhibition of transcription by deoxyadenosine as an alternative mechanism of toxicity. The incubation of resting peripheral blood lymphocytes with deoxyadenosine plus deoxycoformycin led to an inhibition of uridine incorporation. The extent of inhibition increased with the increasing time of incubation and concentration of deoxyadenosine. Replacement of deoxyadenosine with other nucleosides, adenosine or deoxyguanosine, had no effect, suggesting that deoxyadenosine-induced inhibition was not due to the reduced transport of uridine. Separation of DNA from RNA by differential alkaline hydrolysis showed that the reduction of uridine incorporation was primarily in the RNA fraction. The time sequence of the reduction in uridine incorporation coincided with that of the accumulation of dATP, but preceded that of ATP depletion and cell lysis. The phosphorylation of uridine into UTP was slightly reduced by deoxyadenosine, but this could not entirely account for the reduced incorporation of uridine into RNA. Finally, the direct measurement of RNA synthesis by the incorporation of UTP into isolated nuclei showed that RNA synthesis was inhibited to 88% and 41% of control values in lymphocytes preincubated with 20 microM deoxyadenosine for 3 and 15 hr, respectively. These findings demonstrate that deoxyadenosine plus deoxycoformycin inhibits RNA synthesis in resting lymphocytes.

Inhibition of RNA synthesis by deoxyadenosine plus deoxycoformycin in resting lymphocytes

Deoxyadenosine has been implicated in the lymphocytopenia that occurs in immunodeficient children with an inherited deficiency of adenosine deaminase (ADA) and in leukemic patients treated with the ADA inhibitor deoxycoformycin. The recent reports of deoxyadenosine toxicity to nondividing lymphocytes indicates a challenge to the mechanism for deoxyadenosine toxicity, which involves the inhibition of ribonucleotide reductase by dATP, leading to the inhibition of DNA synthesis. This study provides evidence for the inhibition of transcription by deoxyadenosine as an alternative mechanism of toxicity. The incubation of resting peripheral blood lymphocytes with deoxyadenosine plus deoxycoformycin led to an inhibition of uridine incorporation. The extent of inhibition increased with the increasing time of incubation and concentration of deoxyadenosine. Replacement of deoxyadenosine with other nucleosides, adenosine or deoxyguanosine, had no effect, suggesting that deoxyadenosine-induced inhibition was not due to the reduced transport of uridine. Separation of DNA from RNA by differential alkaline hydrolysis showed that the reduction of uridine incorporation was primarily in the RNA fraction. The time sequence of the reduction in uridine incorporation coincided with that of the accumulation of dATP, but preceded that of ATP depletion and cell lysis. The phosphorylation of uridine into UTP was slightly reduced by deoxyadenosine, but this could not entirely account for the reduced incorporation of uridine into RNA. Finally, the direct measurement of RNA synthesis by the incorporation of UTP into isolated nuclei showed that RNA synthesis was inhibited to 88% and 41% of control values in lymphocytes preincubated with 20 microM deoxyadenosine for 3 and 15 hr, respectively. These findings demonstrate that deoxyadenosine plus deoxycoformycin inhibits RNA synthesis in resting lymphocytes.

PISA--a noninvasive method in the evaluation of protective effect of methylprednisolone on the ischemic myocardium

This study deals with the assessment of the PISA--a new noninvasive method, in relation to conventional ECG, MBCPK and LDH1, in the detection and quantification of coronary ligation-induced myocardial damage. Also this study includes the applicability of the PISA method in the evaluation of the effectiveness of methylprednisolone in the protection of myocardial damage, induced by coronary ligation. The studies were conducted in 15 mongrel dogs: (untreated dogs: 9; methylprednisolone (30 mg/kg I.V.) treated dogs: 6). The PISA signature pattern was normal and the PISA index was small in all the dogs before coronary ligation. The PISA signature was phase-variant in all dogs in the untreated group following coronary ligation. The PISA index increased with time following coronary ligation but the changes at 60 minutes were less than at 30 and 120 minutes. There were no significant changes in the conventional ECG, serum MBCPK and LDH1 for the 120 minute duration of coronary ligation. These results indicate the superiority of the PISA method in the detection and quantification of coronary artery ligation-induced myocardial damage. Coronary ligation in methylprednisolone treated dogs produced significant increases in the PISA index with the time but the increases were significantly lower than those in untreated groups. These lower increases at 60 minutes as compared to 30 and 120 minutes observed in the untreated group were absent in the treated group. Methylprednisolone showed some protective effect against coronary ligation-induced myocardial damage. These results indicate that the PISA method may be a valuable tool in the detection and the measurement of the extent of cardiac injury and in constant monitoring of the changes in the size of myocardial damage.

Transcribed chromatin exhibits an altered nucleosomal spacing

The nucleosomal repeat lengths of bulk chromatin and the chromatin of transcriptionally active and inactive genes were analyzed in two mouse cell lines and adult mouse spleens. The adult beta-globin gene exhibits a nucleosomal repeat length approximately 11 base pairs longer than (i) an inactive embryonic globin gene, epsilon y3; (ii) an immunoglobulin heavy chain gene, Cmu; and (iii) the bulk chromatin in murine erythroleukemia cell line DS19. The repeat length of the Cmu gene was approximately 14 base pairs longer than that of the adult beta-globin or epsilon y3 genes in the IgM-producing cell line M104E. The chromatin of several inactive genes had repeat lengths less than or equal to bulk chromatin. Individual genes were shown to vary in repeat length among the cell types examined. In addition, genes that exhibited an increased nucleosomal spacing were digested to mononucleosomes more rapidly than bulk chromatin or inactive genes with shorter repeats. Increased repeat length was also correlated with an increased sensitivity to DNase I. Thus, increased nucleosomal spacing may be a property of transcriptionally active genes or genes with the potential for transcription.

Recovery of locomotor function in cats after localized cerebellar lesions

Cats were trained to walk on a motorized treadmill, at speeds up to a brisk walk, for food reward. A cerebellar lesion was placed in each animal, either unilateral removal of paravermal cortex, or unilateral coagulation of n. interpositus, or bilateral coagulation of the fastigial nuclei. The effects of these lesions upon locomotor activity were measured by conventional kinematic methods, and were found to be generally in agreement with prior observations. Also in agreement with prior work was the fact that these initial deficits disappeared in a relatively short time. The kinematic data suggest that this recovery of function was genuine in the sense that compensatory alterations in limb motion could not be demonstrated. In disagreement with prior studies, we failed to elicit decompensation (e.g. reinstatement of the original deficits) by subsequent pyramidal tract sections, or ablation of the 'motor' cortex. We conclude that the corticospinal system is probably not essential to the recovery observed, and also that perhaps there are substantial differences in the mechanisms of recovery of 'spontaneous' overground locomotion, compared to walking on a treadmill as a conditioned instrumental response.

Interaction of inferior olivary nucleus with reflex bradycardia and tachycardia in the cat

In chloralose-urethane anesthetized cats, stimulation of the ION, apart from directly producing cardioinhibition, was capable of interacting antagonistically with reflex tachycardia (induced by nitroglycerin) and synergistically with reflex bradycardia (induced by phenylephrine). The degree of the potentiation or antagonism was greater than the sum of the individually elicited responses. It was also directly related to the dose of the drugs and the intensity of the stimulating pulse frequency delivered to the nucleus. The similarity in natures of both cardio-inhibitory mechanisms of the ION and gigantocellular reticular nucleus (GRN) has been discussed. We infer that the ION, GRN, nitroglycerin-induced reflex tachycardia and phenylephrine-induced reflex bradycardia may share a final common neural mechanism which function to suppress heart rate. The neurons in the dorsal motor (DM)/solitary (SN) nuclei may be a good candidate, because bilateral vagotomy or unilateral vagotomy with a contralateral DM/SN destruction substantially abolished the cardio-inhibitory effect of both GRN and ION.

Regional metabolic changes in the spinal cord related to spinal shock and later hyperreflexia in monkeys

The regional metabolic rate for glucose (rMRglu) was studied in macaque monkeys after spinal cord transection at T10, both during spinal shock and after reflexes had returned. The rMRglu was measured in all Rexed layers in cord segments both caudal and rostral to the level of the transection utilizing the quantitative [14C]deoxyglucose technique. The monkeys in spinal shock exhibited a significant increase in rMRglu in Rexed layer I and a significant reduction in layers VI to IX of the lumbosacral cord. In contrast, after reflexes had returned the rMRglu was increased in all Rexed layers of the lumbosacral cord; this increase was significant in layers I, V, and VI.