Showing papers by "Worcester Foundation for Biomedical Research published in 1981"
TL;DR: The results show that viral gene products are not required for maintenance of neoplastic transformation and suggest that in lymphoid tumors, an ALV provirus is integrated adjacent to a specific cellular gene, and the insertion of the viral promoter adjacent to this gene results in its enhanced expression, leading to neoplasia.
484 citations
TL;DR: Results indicate that the HDB is the major source of cholinergic afferents to the main olfactory bulb (MOB) in the hamster.
Abstract: A series of neuroanatomical, biochemical, and histochemical studies have been conducted to determine the sources of cholinergic afferents to the main olfactory bulb (MOB) in the hamster. Following horseradish peroxidase (HRP) injections that are restricted to the MOB, retrograde neuronal labeling is observed bilaterally in the anterior olfactory nucleus, locus coeruleus, and raphe nuclei, and ipsilaterally in the ventral hippocampal rudiment, dorsal peduncular cortex, piriform cortex, nucleus of the lateral olfactory tract, anterior pole of the medial septal area and vertical limb of the diagonal band, nucleus of the horizontal limb of the diagonal band (HDB), and hypothalamus. Spread of HRP into the accessory olfactory bulb results in additional neuronal labeling ipsilaterally in the bed nucleus of the accessory olfactory tract, medial amygdaloid nucleus, and bed nucleus of the stria terminalis, and bilaterally in the posteromedial cortical amygdaloid nucleus. Retrograde tracing studies also have been conducted in cases with lesions in the basal forebrain or hypothalamus to assess the extent to which such lesions interrupt fibers of passage from other sources of centrifugal afferents, and the effects of such lesions on choline acetyltransferase (CAT) activity and catecholamine content in the MOB and on acetylcholinesterase (AChE) activity in the forebrain have been evaluated. Lesions in the basal forebrain reduce or eliminate CAT and AChE activity in the MOB in direct relationship to the extent of damage to the HDB. Norepinephrine (NE) content in the MOB also is reduced by basal forebrain lesions, but in relationship to damage of the medial forebrain bundle (MFB). The hypothalamic lesions have no effect on AChE activity in the forebrain or on CAT activity in the MOB, but they eliminate retrograde labeling in the locus coeruleus and raphe nuclei and reduce the NE content of the MOB to undetectable levels. The dopamine content of the MOB is not reduced by any of the lesions. Anterograde tracing studies have been conducted to compare the rostral projection patterns of the HDB with the distribution of AChE activity. Most of the rostrally directed axons travel in association with the MFB. A small component of axons travels in association with the lateral olfactory tract. Within the MOB, the axons terminate predominantly in the glomerular layer and in the vicinity of the internal plexiform layer. The projection and termination patterns of the HDB correspond well with the distribution of AChE activity. These various results indicate that the HDB is the major source of cholinergic afferents to the MOB.
217 citations
TL;DR: The laminar termination patterns of cortical afferents to the ipsilateral MOB thus are correlated with the mediolateral axis of the olfactory peduncle and the rostrocaudalaxis of the piriform cortex.
Abstract: The centrifugal projections from the various subdivisions of the anterior olfactory nucleus (AON) can be categorized into four groups based on the organization of terminal fields in the main olfactory bulb (MOB). Pars lateralis and dorsalis have bilaterally asymmetric laminar projections to the MOB. The ipsilateral projections terminate primarily in the superficial half of the granule cell layer and in the deep third of the glomerular layer, whereas the contralateral projections terminate primarily in the superficial half of the granule cell layer and do not extend into the glomerular layer. Pars ventralis and posterior have bilaterally symmetric laminar projections with heavy terminations both in the superficial half of the granule cell layer and in the deep third of the glomerular layer. Pars medialis sends predominantly ipsilateral projections to the deep half of the granule cell layer. Pars externa has predominantly contralateral projections with a very narrow terminal field immediately deep to the internal plexiform layer. The projections to the MOB from the ventral hippocampal rudiment (HR) and the piriform cortex (PC) are exclusively ipsilateral. The projections from the ventral HR terminate primarily in the deep half of the granule cell layer. The projections from the PC also terminate predominantly in the granule cell layer, but there is a progressive shifting of terminal fields from the superficial half of this layer toward deeper regions for centrifugal axons arising from progressively more caudal levels of the PC. The laminar termination patterns of cortical afferents to the ipsilateral MOB thus are correlated with the mediolateral axis of the olfactory peduncle and the rostrocaudal axis of the piriform cortex.
The centrifugal axons from these various sources enter directly into the granule cell layer of the caudal MOB or pass through the internal plexiform layer of the accessory olfactory bulb to reach the middle and anterior part of the MOB. We have termed these two routes the final common bulbar pathway. The centrifugal axons from the laterally situated sources join the anterior and bulbar limbs of the anterior commissure before entering the final common bulbar pathway. In contrast, the centrifugal axons from pars medialis and the ventral HR travel diffusely in the cellular layer of the ipsilateral olfactory peduncle. A small component of the centrifugal projections from the PC travels in association with the lateral olfactory tract.
170 citations
TL;DR: Results demonstrate that U1 is base-paired with hnRNA in vivo, suggesting a role in mRNA processing, and demonstrate that snRNAs U3 and 5.8S rRNA to be cross-linked to nucleolar RNA.
111 citations
TL;DR: Progesterone modulates the action of estrogen by controlling nuclear retention of the estrogen-receptor complex through selective action on the occupied form of the nuclear estrogen receptor, with no effect on the concentration of an unoccupied form.
Abstract: Total concentrations of estrogen receptor in the uterine nuclear fraction are reduced rapidly after progesterone treatment of the proestrous hamster. Progesterone acts selectively on the occupied form of the nuclear estrogen receptor, with no effect on the concentration of an unoccupied form. This observation indicates that progesterone modulates the action of estrogen by controlling nuclear retention of the estrogen-receptor complex.
89 citations
TL;DR: It is suggested that newly synthesized mRNA molecules emerging from the nucleus into the cytoplasm shed the proteins with which they were associated in the nucleus and become associated with a new set of proteins derived from the cytosol.
83 citations
TL;DR: Observations suggest that calmodulin is involved in regulating the transport of cholesterol to mitochondria, a process that is stimulated by LH and cAMP and one that may account for the increased steroid synthesis produced by these agents.
Abstract: Two approaches were used to study the possible role of calmodulin in the regulation of synthesis of testosterone by Leydig cells: trifluoperazine was used as an inhibitor of calmodulin and liposomes were used to deliver calmodulin into the cells. The inhibitor prevented the expected responses of Leydig cells to LH and to cAMP. First the increase in synthesis of testosterone produced when these agents are added to Leydig cells was inhibited by the drug. Second, increased transport of cholesterol to mitochondria produced by LH and cAMP was inhibited by trifluoperazine. Third, increased side-chain cleavage of cholesterol (cholesterol leads to pregnenolone) produced by these agents in isolated mitochondria was also inhibited by the drug. When Leydig cells were incubated with liposomes containing calmodulin, production of testosterone, transport of cholesterol to mitochondria, and side-chain cleavage of cholesterol were all stimulated. The effect of calmodulin is greater if Ca2+ is added before incorporation into liposomes than if calmodulin and Ca2+ are introduced into the Leydig cells from separate liposomes. Stimulation of testosterone synthesis does not occur if calmodulin is dialyzed against EGTA, if calmodulin with excess anticalmodulin is present in the liposomes, if either calmodulin or Ca2+ is added to the medium (no liposomes), or if Ca2+ alone is present in liposomes. These observations suggest that calmodulin is involved in regulating the transport of cholesterol to mitochondria, a process that is stimulated by LH and cAMP and one that may account for the increased steroid synthesis produced by these agents.
81 citations
TL;DR: Estradiol was found to inhibit both activities of the purified enzyme with Δ 4 and with Δ 5 substrates (progesterone, pregnenolone, and the corresponding 17α-hydroxysteroids).
Abstract: Highly purified cytochrome P-450 from neonatal pig testicular rnicrosomes is capable of catalyzing both 17αhydroxylation and C-17,20-lyase activity. Estradiol was found to inhibit both activities of the purified enzyme with Δ 4 and with Δ 5 substrates (progesterone, pregnenolone, and the corresponding 17α-hydroxysteroids). For the Δ 4 series, inhibition of lyase is competitive and that of 17α-hydroxylase is noncompetitive; for the Δ 5 series, inhibition was noncompetitive for both activities. Ki values for lyase activity were determined from enzyme kinetics (5.0 μM for the Δ 4 substrate and 20 μM for the Δ 55 substrate). Estradiol produces a typical type I spectral shift with the pure enzyme (Ks = 3.0 μ where Ks is the concentration of steroid required to give half maximal spectral shift), so that Ki values were also determined directly from binding studies by using substrate-induced difference spectroscopy. Fifty per cent inhibition of the maximal spectral shift induced by the 17α-hydroxysubstrates (Ki) ...
68 citations
TL;DR: The nucleus raphe dorsalis is organized as a reticular nucleus with neurons having few, straight and poorly ramified dendrites with the most striking age-related changes in the multipolar and ovoid-shaped cells.
64 citations
01 Jan 1981
61 citations
TL;DR: It is demonstrated that progesterone rapidly and selectively decreases nuclear Re levels in rat uterus and suggested that this process is not dependent on cytosol Re or serum estradiol levels.
TL;DR: It is shown that the synthesis of actin is regulated developmentally during early sea urchin embryogenesis and that the level of synthesis of this protein parallels the steady-state amounts of the actin messenger ribonucleic acids (RNA).
Abstract: We show that the synthesis of actin is regulated developmentally during early sea urchin embryogenesis and that the level of synthesis of this protein parallels the steady-state amounts of the actin messenger ribonucleic acids (RNA). An in vitro translation and RNA blotting analysis of embryo RNA from several stages of early development indicated that during the first 8 h after fertilization there was a low and relatively constant level of actin messenger RNA in the embryo. Between 8 and 13 h of development, the amount of actin messenger RNA began to increase both in the cytoplasm and on polysomes, and by 18 h the amounts of actin message per embryo had risen between approximately 10- and 25-fold in the cytoplasm and between 15- and 40-fold on polysomes. Two size classes of actin messenger RNA (2.2 and 1.8 kilobases) were identified in unfertilized eggs and in all of the developmental stages examined. The amount of each actin message class increased over a similar time interval during early development. However, the amounts of these size classes in the cytoplasm relative to each other shifted between the earliest stages examined (2 to 5 h) and the hatching blastula stage (18 h), with the ratio of the 1.8-kilobase actin messenger RNA to the 2.2-kilobase actin messenger RNA increasing almost threefold during this period.
TL;DR: Results showed that the GABA bloeker, picrotoxin, attenuated the effects of lateral habenula stimulation on unit activity in the raphe dorsalis and medianus and that GABA may exert a tonic inhibitory influence on spontaneous unit activity with indirect evidence that norepinephrine and possibly histamine exerted an excitatory effect on raphe units.
TL;DR: The fusiform and ovoid cells show either little change or a decreased synaptic input at all ages, while the presumed serotonergic multipolar cells showed an increase, in agreement with neurochemical studies in these rats showing increased levels of this biogenic amine in protein malnourished rats.
TL;DR: It is concluded that age, per se, does not appear to influence thePR values for A, T and E1 but does for E2, and the subjects weight, however, has a major influence for the PR values of all four steroids.
TL;DR: Evidence is discussed that some long-term cell lines thought to be related to the neoplastic cell of Hodgkin's disease but are not, in fact, related but are non-human contaminants.
Abstract: Several laboratories have recently reported the establishment and characterization of long-term cell lines thought to be related to the neoplastic cell of Hodgkin's disease. Here, Harris et al. discuss evidence that some of these lines are, in fact, not related to Hodgkin's disease but are non-human contaminants.
TL;DR: Although gossypol has been shown to be an effective antifertility agent in several mammalian species, it failed to exhibit such an effect in Dutch-belted rabbits, although serum T levels were reduced.
TL;DR: Observations support the hypothesis that progesterone modulation of estrogen action may be accomplished by induction (or activation) of an estrogen receptor-regulatory factor (Re-RF), and this factor may in turn act to eliminate the occupied form of estrogen receptor from the nucleus, perhaps through a hypothetical dephosphorylation-inactivation mechanism.
Abstract: In vitro studies have demonstrated a progesterone-induced activity associated with the uterine nuclear fraction which resulted in the loss of nuclear estrogen receptor. Uterine nuclear suspension or nuclear KC1 (0.5 M) extract from control and progesterone-treated (30 min or 2h) hamsters were incubated at 37 C for 0, 15, or 30 min in Tris-glycerol buffer. Preparations from progesterone-treated hamsters showed an accelerated reduction of total estrogen receptor which was primarily due to preferential loss of occupied receptor. This progesterone-dependent stimulation of estrogen receptor loss was absent when nuclear extract was prepared in phosphate buffer rather than Tris buffer. In addition, sodium molybdate and sodium metavanadate (both at 10 mM) inhibited this activity in nuclear extract. These observations support the hypothesis that progesterone modulation of estrogen action may be accomplished by induction (or activation) of an estrogen receptor-regulatory factor (Re-RF), and this factor may in turn ...
TL;DR: The results indicate the presence of a countercurrent transfer mechanism for progesterone between the ovarian vein and the ovarian artery and that radioactivity in ovarian arterial plasma showed a significantly greater increase compared to the increase in the equivalent volume of aortic plasma collected simultaneously.
Abstract: >3H]Progesterone, [14C]progesterone, and [125I]-bovine serum albumin were infused sequentially for 30-min periods into an ovarian vein close to the hilus of the ovary in sheep. Radioactivity was determined in plasma obtained from blood samples withdrawn simultaneously from the adjacent ovarian artery near the hilus of the ovary and from the aorta. During the infusion of labeled progesterone, radioactivity in ovarian arterial plasma showed a significantly greater increase compared to the increase in the equivalent volume of aortic plasma collected simultaneously. After the infusion of [125I]bovine serum albumin in the same manner as labeled progesterone, there was no observed difference in γ-radioactivity between plasma samples from the ovarian artery and the aorta. These results indicate the presence of a countercurrent transfer mechanism for progesterone between the ovarian vein and the ovarian artery. The concomitant infusion of prostaglandin F2n (PGF2a) into the ovarian vein did not decrease the transf...
TL;DR: The results suggest that membrane curvature may be induced by diacyglycerol phosphorylation at the inner surface of the membrane bilayer, while the membrane skeleton limits the curvature and determines the shape ultimately assumed.
Abstract: Red cell membranes prepared by hemolysis and washing in hypotonic Tris buffer crenate when suspended at 0 degrees C in isotonic medium. At 37 degrees C, in the presence of 1 mM MgATP, the crenated membranes are progressively converted to smooth-contoured discs and cup-forms. The phosphorylation of proteins and lipids during shape transformation in the presence of [gamma-32P]ATP has been studied. Spectrin phosphorylation and shape change could be dissociated in several ways, demonstrating that spectrin phosphorylation is neither necessary nor sufficient for the membrane smoothing reaction. Adenosine markedly inhibited phosphoinositide regeneration without altering shape change. Phosphatidic acid synthesis from endogenous diacylglycerol was not affected by adenosine and comparison of sheep, human and rabbit ghosts, which vary greatly in shape change capacity, demonstrated a direct correlation between phosphatidic acid synthesis and shape change rate. The results suggest that membrane curvature may be induced by diacyglycerol phosphorylation at the inner surface of the membrane bilayer, while the membrane skeleton limits the curvature and determines the shape ultimately assumed.
TL;DR: Total radioactivity, unconjugated 4-hydroxy-4-androstene-3,17-dione (4-OHA) and unconjugate 4,17β-dihydroxy- 4- androstenes-3-one ( 4-OHT) were measured in whole blood 1–180 min after intravenous administration of [ 3 H]-4- OHA to two male rhesus monkeys.
TL;DR: The findings suggest that the cytochalasins inhibit steroidogenesis and produce rounding of cells by interfering with polymerization of actin and not in as the result of effects unrelated to binding to actin.
TL;DR: The predominant effect of elevated levels of adenosine 3',5'-monophosphate in Aplysia neurons was an increased slope conductance to hyperpolarizing pulses, evident in voltage clamp records, consistent with the idea that cyclic nucleotides are important in the expression of synaptic alteration of bursting pacemaker activity.
Abstract: Bursting pacemaker activity in nerve cells can be modified for long periods by synaptic input of short duration. There is evidence that cyclic nucleotides may play a role in these modifications. The predominant effect of elevated levels of adenosine 3',5'-monophosphate in Aplysia neurons was an increased slope conductance to hyperpolarizing pulses, evident in voltage clamp records. A similar increase in slope conductance was seen as one component of maximum strength synaptic stimulation, which is consistent with the idea that cyclic nucleotides are important in the expression of synaptic alteration of bursting pacemaker activity.
TL;DR: Experiments in the golden hamster indicate that a period of increased PRL secretion either initiates, or is initially necessary for, spontaneous recrudescence or changes in testicular hCG binding occurring during spontaneous recreation, but no definite conclusions are drawn concerning a possible cause-and-effect relationship.
Abstract: Experiments were conducted in the golden hamster to determine temporal relationships and statistical correlations between plasma PRL concentrations and unoccupied testicular hCG binding sites during short photoperiod-induced testicular regression and spontaneous recrudescence. Although two experiments provided statistically significant (P
TL;DR: There is sufficient DMDS present each day in the female's vagina to account for her persistant attractiveness to males in the typical laboratory bioassay.
TL;DR: Steady state voltage clamp techniques were used to examine the alterations of membrane characteristics produced in these different cell types by cyclic nucleotides, and 8-benzylthio-cAMP affected only the slope conductance in R15.
TL;DR: Though the liver and brain 2-hydroxylase appears to be cytochrome P-450 mediated, it does not respond significantly to certain typical inducers of monooxygenase such as 3-methylcholanthrene and phenobarbital.
TL;DR: It is concluded that 17α-hydroxylation is a necessary step in side-chain cleavage of C21 steroids catalyzed by the microsomal enzyme, supporting the idea that pregnenolone is the preferred substrate.
01 Jan 1981
TL;DR: 127 I and 125 I analogs of estrogens were synthesized and their abilities to bind to uterine receptors, to translocate these receptors to the nucleus, and to bind in vivo to mammary tumors in rats were studied.