Biomedical subjects

M Cimino

Publications and source records attributed to M Cimino.

At least 19 recordsLinked to original sources

PubMed1992

Cellular expression of somatostatin in MAM-induced microencephaly in the rat.

Methylazoxymethanol acetate (MAM) is a mitotic inhibitor that has been used to selectively destroy neuroblasts at specific times during gestation. The administration of MAM results in a dose-dependent microencephaly. Following MAM treatment at 15 days of gestation, we have noted an increase in the level of SS immunoreactivity in the neocortex, as determined by radioimmunoassay. Northern blot analysis for preproSS mRNA revealed an increase in MAM-treated cortex. The cellular distribution of SS has been determined using in situ hybridization and immunocytochemistry. There was a 30% increase in the density of SS-immunoreactive neurons in the cortex of the MAM-treated animals. These data suggest that SS neurons in the cortex are spared following MAM treatment at GD 15.

Animals↗

PubMed1992

The phosphorylation state of DARPP-32, a third messenger for dopamine, is regulated by in vivo pharmacological treatments.

It has been recently proposed that DARPP-32 participates, as third messenger, in the mediation of effects induced by dopamine at the cellular level. DARPP-32 is indeed localized almost exclusively on dopaminoceptive neurons bearing the D1 receptor subtype and it is phosphorylated by cAMP-dependent protein kinase. In its phospho-form, DARPP-32 acts as an inhibitor of protein phosphatase-1. In vivo pharmacological treatment with selective D1 agonists and antagonists induces changes in the phosphorylation state of DARPP-32 that can be correlated to changes in cAMP, mediated in turn by D1 and D2 receptors. These data demonstrate that the measurement of the phosphorylation state of DARPP-32 with the back-phosphorylation assay can represent a useful biochemical tool to gain further insight into the sequence of events elicited by specific dopaminergic drugs in vivo.

Animals↗

PubMed1992

Distribution of nicotinic receptors in cynomolgus monkey brain and ganglia: localization of alpha 3 subunit mRNA, alpha-bungarotoxin and nicotine binding sites.

The distribution of nicotinic receptors in the brain and ganglia of the Cynomolgus monkey was studied by in situ hybridization and receptor autoradiography. A 35S-labeled antisense riboprobe for the mRNA of the alpha 3 subunit of the human nicotinic receptor, [3H]L-nicotine and [125]alpha-bungarotoxin were used as markers. The highest levels of alpha 3-mRNA were observed in the hippocampus, the medial habenula, the lateral geniculate, the granular layer of the cerebellum, as well as in the pineal gland; moderate levels were found in other nuclei of the thalamus and in the deeper layers of the cerebral cortex. High-affinity binding sites for [3H]L-nicotine were observed mainly in the thalamus. The distribution of [125I]alpha-bungarotoxin binding sites was different from that observed for alpha 3-mRNA and [3H]L-nicotine; they were most abundant in a few specific thalamic nuclei, in the medial habenula and in lamina I of the cerebral cortex. The localization of these three markers was also investigated in the sympathetic, parasympathetic and sensory ganglia of the monkey. Intense labeling was observed for alpha 3-mRNA and for [125I]alpha-bungarotoxin in the sympathetic and parasympathetic ganglia, whereas no positive signal was seen in the ganglion of Gasser. [3H]L-nicotine binding was not detected in any of the ganglia examined. High levels of mRNA for the alpha 3 subunit of the nicotinic receptor were also detected in human sympathetic ganglia. Comparison between alpha 3-mRNA distribution and [3H]L-nicotine binding suggests that in the Cynomolgus monkey brain, the alpha 3 subunit may participate in the formation of more than one nicotinic receptor subtype: a high-affinity binding site for [3H]L-nicotine in the thalamus, and other sites with low affinity for nicotine in the medial habenula and cerebral cortex. Both the alpha 3-mRNA and the [125I]alpha-bungarotoxin are highly expressed in the sympathetic ganglia; however, since no information is presently available on the intraneuronal cellular localization, it cannot be established whether or not they are both present at synaptic sites.

Animals↗

PubMed1991

Differential ontogenetic expression and regulation of proenkephalin and preprosomatostatin mRNAs in rat caudate-putamen as studied by in situ hybridization histochemistry.

Specific oligonucleotide probes and in situ hybridization histochemistry were used to study the ontogeny and regulation of the mRNAs for proenkephalin A and preprosomatostatin in rat brain. In adult brain the most intense hybridization signal for the proenkephalin A mRNA was in caudate putamen, nucleus accumbens and olfactory tubercle. By contrast, the hybridization signal for preprosomatostatin mRNA was more diffusely scattered throughout the brain, with high signals in the neocortex, olfactory bulb and hippocampal formation. Studies of the ontogeny of these mRNAs revealed a different pattern of ontogenetic expression and differential regulation by dopaminergic input. The mRNA for preposomatostatin reached the highest level within the first postnatal week, whereas proenkephalin A mRNA progressively increased throughout the entire period studied. In addition the proenkephalin A mRNA showed a medial to lateral gradient in 2-day-old rat striatum which disappeared with increasing age, whereas preprosomatostatin mRNA increased in most brain areas in fairly uniform fashion with increasing age. Treatment of newborn rats with 6-hydroxydopamine increased the expression of proenkephalin A mRNA by 1.6 fold but had no effect on the expression of preprosomatostatin mRNA. The 6-hydroxydopamine-induced change in proenkephalin A mRNA expression was not observed until postnatal day 32, indicating that enkephalin-containing neurons of the developing striatum are relatively insensitive to dopamine input and that they cannot compensate for the neonatal lesion, despite the fact that the insult was given in a period of high plasticity of the neural tissue.

Aging↗

PubMed1991

Decrease in mRNA levels but not in the density of D2 dopamine receptors in rat striatum after transient forebrain ischemia.

D2 dopamine receptor mRNA was analyzed by in situ hybridization histochemistry in rat striatum 7 days after transient forebrain ischemia. A patchy disappearance of the D2 receptor mRNA was observed in the dorsolateral striatum. In the same area, a disappearance of D1 binding sites occurred in the absence of significant changes in D2 receptor density. These results suggest that, although D2 receptors seem to be apparently unaffected after forebrain ischemia, a long-lasting impairment of their neosynthesis may be present in striatal D2 dopaminoceptive neurons.

Animals↗

PubMed1991

Microencephaly reduces the phosphorylation of the PKC substrate B-50/GAP43 in rat cortex and hippocampus.

The administration of the antimitotic agent methylazoxymethanol (MAM) to rats at day 15 of gestation results in a consistent loss of intrinsic neurons primarily in cortex and hippocampus. These animals when adult, show a cognitive impairment, if tested in specific behavioural tasks. B-50/GAP43 is a neuronal phosphoprotein, specific substrate for protein kinase C (PKC) and involved in the development and plasticity of synaptic connections. Since B-50/GAP43 has been implicated in functional modulation of synapses and in the molecular mechanism underlying cognitive processes, we studied the phosphorylation of B-50 in cortex and hippocampus of control and MAM-treated rats. Here we report that B-50 in MAM-treated rats shows a marked reduction in the phosphate incorporation in the areas affected by the prenatal treatment. In situ hybridization studies demonstrate that the mRNA levels for B-50 are not altered in MAM-treated rats and that the relative amount of the protein, as revealed by Western blot analysis, is also not affected in microencephalic rats. These results suggest that microencephalic animals might represent a useful experimental model to study biochemical correlates of cognitive impairment and synaptic plasticity.

Animals↗

PubMed1990

Ontogenetic development of calmodulin mRNA in rat brain using in situ hybridization histochemistry.

An oligonucleotide probe complementary to the area on calmodulin coding for the calcium binding domain II on calmodulin was used to study the ontogenetic development of calmodulin mRNA in rat brain using in situ hybridization histochemistry. The hybridization signal for this probe was saturable, RNAse sensitive and was displaced by excess unlabelled calmodulin probe but was not displaced by an S-100 probe or by another calmodulin probe which was complementary to the mRNA coding for a different portion of calmodulin. At birth, high levels of calmodulin mRNA were found in hippocampus, cerebral cortex, thalamic nuclei and corpus striatum, and relatively low levels were in white matter. The rate at which calmodulin mRNA changed during development in the different brain areas varied with the brain area. At postnatal day one, the highest hybridization signals were in the cortical plate of the cerebral cortex, in thalamus and in the pyramidal cell layers of hippocampus and pyriform cortex. This distribution became more uniform with age. In contrast to most other brain areas, calmodulin mRNA in cerebellum increased markedly between one and 32 days postnatal; the hybridization signal was low at day one and was confined to the external germinal layer, but by day 16 calmodulin mRNA was largely in the granular layer. These results taken together with other findings on the effects of calmodulin on cellular growth differentiation, suggest that calmodulin may play a role in neuronal maturation.

Aging↗

PubMed1990

Morphometrical and microdensitometrical studies on peptide- and tyrosine hydroxylase-like immunoreactivities in the forebrain of rats prenatally exposed to methylazoxymethanol acetate.

Methylazoxymethanol acetate (MAM Ac) injected into pregnant rats at a dose of 25 mg/kg at gestational day 15 causes microcephaly due to an atrophy of various telencephalic areas, mainly neocortex, hippocampus and basal ganglia. Previous studies demonstrated alterations in various neurochemical markers of classical transmitter systems in these regions. The present paper deals with changes in peptide and tyrosine hydroxylase (TH)-containing neurons in MAM Ac-induced microcephaly using immunocytochemistry coupled with computer-assisted morphometry and microdensitometry. No change in the number of vasoactive intestinal polypeptide (VIP)-immunoreactive neurons in the neocortex and neuropeptide Y (NPY)-immunoreactive neurons in the nucleus caudatus-putamen was found whereas cholecystokinin (CCK)-and NPY-immunoreactive neurons in the neocortex and CCK- and VIP-immunoreactive neurons in the hippocampus were decreased. The reduction of the latter peptide containing neuronal populations led to a maintained density of cells in MAM Ac-exposed rats, due to the parallel reduction of the overall mass of these regions. TH immunoreactivity was found to be unchanged in the basal ganglia, and increased in the cerebral cortex in agreement with previous reports on noradrenaline cortical system after MAM Ac exposure. The present results show a heterogenous vulnerability of different peptide immunoreactive neuronal populations to MAM Ac exposure. The sparing of VIP- and NPY-immunoreactive neurons may be due to their late development in the neocortex and striatum, respectively. The hypothesis is introduced that cortical VIP interneurons can develop independent of marked alterations in the intrinsic circuitry of the cortical region.

Animals↗

PubMed1990

Anatomical localization of calmodulin mRNA in the rat brain with cloned cDNA and synthetic oligonucleotide probes.

Calmodulin is a small, acidic calcium-binding protein that regulates a number of calcium-dependent enzyme activities and is thought to be involved in neurotransmission. To begin to explore further the regulation of this important protein in the brain, we have cloned a rat calmodulin cDNA and designed an oligonucleotide probe based on this sequence. Both the cDNA and oligonucleotide probes revealed a markedly heterogeneous distribution of hybridization signal for calmodulin mRNA in the rat brain. The greatest apparent abundance of mRNA for calmodulin was seen in the hippocampus and cerebral cortex, whereas many brain regions showed relatively low hybridization signal, including the striatum and portions of the hypothalamus and brainstem.

Animals↗

PubMed1990

Developmentally regulated expression of calcitonin gene-related peptide at mammalian neuromuscular junction.

Using indirect immunofluorescence techniques, we have found that calcitonin gene-related peptide-like immunoreactivity is present in the neuromuscular junctions of somatic muscles as well as in almost all motor neurons of the lumbar enlargement of 1-week-old rats. It gradually decreases in both motor neurons and motor nerve endings as the animal grows up and completely disappears from the neuromuscular junctions in adult rats, persisting only in the motor nerve endings on the intrafusal fibers. In situ hybridization experiments have shown that the down-regulation of calcitonin gene-related peptide-like immunoreactivity is strictly related to a reduction in CGRP mRNA levels in the spinal motor neurons. These results indicate that the expression of CGRP is developmentally regulated in spinal cord alpha motor neurons. They also suggest that the peptide may play an important role at the immature neuromuscular junction.

Aging↗

PubMed1990

Free and liposomal doxorubicin treatment of intraperitoneal colon 26 tumor: therapeutic and pharmacologic studies.

Intraperitoneal (i.p.) chemotherapy is being investigated as an adjunct to surgery to kill residual cancer cells, inhibit cancer cell seeding, local recurrence, and metastases for ovarian, gastric, and colon cancers. In this report, the therapeutic effects of Doxorubicin (Dox) and liposome-entrapped Dox (Dox-Lip) against i.p. mouse colon 26 (C26) tumor were compared. It was found that Dox-Lip was less toxic than Dox after i.p. administration in non-tumor bearing animals. I.P. Dox and Dox-Lip significantly inhibited the growth of C26 tumor when the treatment was initiated 1 day after tumor cell inoculation, but both administration forms were ineffective against well-established (8-day) tumors. Multiple dose schedules did not improve the therapeutic response. Dox-Lip was not therapeutically superior to Dox at equal doses or at approximately equi-toxic doses. In addition, the relative retention of Dox and Dox-Lip in the peritoneal cavity and their plasma pharmacokinetics were investigated. It was found that Dox levels in the peritoneal cavity were maintained for longer periods after i.p. Dox-Lip was administered. However, the results show that maintenance of elevated drug levels in the peritoneal cavity does not necessarily lead to increased therapeutic effects.

Animals↗

PubMed1989

In vivo modulation of striatal phosphoproteins by dopaminergic agents.

Protein phosphorylation in the brain represents a common target for several second messenger systems. A phosphoprotein (DARPP-32) specifically regulated by cAMP and dopamine has been detected in neurons bearing dopamine D-1 receptors, where it plays a key role in eliciting cAMP-mediated intracellular responses. The endogenous phosphorylation of this cytosolic protein is markedly affected after in vivo acute treatment with the selective D-1 agonist, SKF 38393. The amount of the DARPP-32 dephospho-form measured by a back-phosphorylation assay was decreased by about 30% in agonist-treated animals. This effect was completely counteracted by the concomitant administration of the selective D-1 antagonist, SCH 23390, but not by a selective D-2 antagonist. This first demonstration of in vivo modulation of the phosphorylation state of DARPP-32 could, as a biochemical approach, represent a useful tool to gain further insight into the cascade of biochemical events elicited by specific dopaminergic drugs.

2,3,4,5-Tetrahydro-7,8-dihydroxy-1-phenyl-1H-3-ben↗

PubMed1989

Methylazoxymethanol-induced microencephaly: persistent increase of cortical somatostatin-like immunoreactivity.

Treatment of pregnant rats with methylazoxymethanol (MAM) at day 15 of gestation induces a marked microencephaly in the offspring, characterized by impaired formation of interneurons in the areas affected. We have measured somatostatin immunoreactivity in the cortex, striatum and hippocampus of the offspring of pregnant rats treated with graded doses of MAM. A long-lasting increase in the cortical levels of this peptide was found, suggesting that somatostatinergic interneurons might be selectively spared by administration of the cytotoxic agent at this gestational age.

Animals↗

PubMed1989

Synthesis and dopamine receptor affinities of 6-amino-5,6,7,8-tetrahydroquinoline derivatives.

Some N,N-dialkylderivatives of 6-amino-5,6,7,8-tetrahydroquinoline were synthesized. The affinity of new compounds for dopamine binding sites was measured in a test involving displacement of [3H]SCH 23390 (D-1 selective) and [3H]spiperone (D-2 selective) from homogenized rat striatal tissue. While no compound was effective in displacing [3H]SCH 23390, in the binding assays on the D-2 receptor all tetrahydroquinolines displaced [3H]spiperone from specific binding sites, the compounds with a N-n-propyl-N-phenylethylamino group (18) or N,N-di n-propylamino group (16) being the most potent.

2,3,4,5-Tetrahydro-7,8-dihydroxy-1-phenyl-1H-3-ben↗

PubMed1988

Cefoperazone plus piperacillin versus mezlocillin plus tobramycin as empiric therapy for febrile episodes in neutropenic patients.

The double beta-lactam combination of cefoperazone plus piperacillin was compared with an aminoglycoside-containing regimen of mezlocillin plus tobramycin in a prospective, randomized trial of empiric therapy for febrile neutropenic patients (neutrophils no more than 1,000/mm3). Thirty febrile episodes were treated with cefoperazone plus piperacillin and mezlocillin plus tobramycin, respectively. There was no significant difference between the two groups with respect to age, sex, pretherapy neutrophil count, and mean duration of therapy. The majority of patients had neutrophil counts of no more than 200/mm3 at the initiation of therapy. Only microbiologically and clinically documented infections were evaluated for efficacy. The cefoperazone plus piperacillin regimen appeared to have a comparable response rate with the mezlocillin plus tobramycin regimen (20 of 24 patients [83 percent] versus 16 of 23 patients [70 percent]). Gram-positive micro-organisms were seen predominantly in this study, with the cefoperazone plus piperacillin regimen achieving a bacteriologic response in 84 percent, as opposed to 60 percent for those organisms treated with the mezlocillin plus tobramycin regimen. Neither regimen was totally effective against coagulase-negative staphylococci. Eight superinfections occurred in the cefoperazone plus piperacillin arm, whereas 11 superinfections occurred in the mezlocillin plus tobramycin arm. Although fungal superinfections were most common, the number of gram-positive superinfections in the mezlocillin plus tobramycin arm exceeded those seen in the cefoperazone plus piperacillin arm. The incidence of antibiotic-related side effects was similar in the two groups. Hypokalemia was most frequently seen. Both skin rashes and nephrotoxicity were more common with mezlocillin plus tobramycin. Cefoperazone plus piperacillin was found to be effective empiric therapy in febrile neutropenic patients. This double beta-lactam combination may be particularly useful for patients who have or are at high risk for the development of renal insufficiency.

Adolescent↗

PubMed1988

Characteristics of the binding of phenoxybenzamine to calmodulin.

To determine the factors that influence the interaction between phenoxybenzamine and calmodulin, the binding of phenoxybenzamine to calmodulin was determined by equilibrium dialysis under a variety of experimental conditions. This interaction was found to be similar in some respects to the interaction between phenothiazines and calmodulin. It was saturable, with between 1 and 2 mol of phenoxybenzamine bound to 1 mol of calmodulin. It was also dependent upon temperature, the presence of a divalent cation such as calcium, and on pH, showing maximum binding at pH 6.5 with little binding at pH values below 4.2 or above 8.0. The site at which phenoxybenzamine bound to calmodulin appears to be similar to that at which certain antipsychotic agents bind, since several of them, including penfluridol, pimozide and spiroperidol, prevented the binding of phenoxybenzamine to calmodulin. However, in contrast to the reversible binding of most phenothiazines to calmodulin, phenoxybenzamine bound to calmodulin irreversibly. The binding of phenoxybenzamine to calmodulin was fairly selective in that other alpha-adrenergic agents such as prazosin, yohimbine and clonidine failed to bind to calmodulin when examined under the same experimental conditions. In addition, phenoxybenzamine showed little or no calcium-dependent binding to the S-100 protein, bovine serum albumin or cytochrome c. The irreversible complex between phenoxybenzamine and calmodulin may be useful for inhibiting certain calmodulin-dependent reactions and for studying the various biological functions of calmodulin.

Calmodulin↗

PubMed1988

Chronic uridine treatment reduces the level of [3H]spiperone-labelled dopamine receptors and enhances their turnover rate in striatum of young rats: relationship to dopamine-dependent behaviours.

The effect was studied of chronic uridine treatment on the recovery of striatal D-2 dopamine (DA) receptors after their irreversible blockade by N-ethoxycarbonyl-2-ethoxy-I,2-dihydroquinoline (EEDQ) in young (40 days old) and adult (14 months old) male rats using [3H]spiperone as radioligand. Chronic uridine treatment (15 mg kg-1 day-1, i.p., 14 days) causes a reduction of [3H]spiperone binding sites in striatum of young rats. This treatment also produces an increase in the rate of recovery of striatal [3H]spiperone-labelled DA receptors in young, but not in adult rats. Catalepsy and exploratory locomotor activity, two behaviours associated with blockade versus activation of DA receptors, were evaluated in the same rats. The behavioural recovery from the EEDQ-induced syndrome is more rapid in the young rats treated with uridine than in the saline-treated group. The behavioural recovery in old rats was not affected by chronic uridine treatment. Thus, in young rats the pyrimidine nucleoside uridine may modulate the steady state and the turnover rate of striatal D-2 DA receptors.

Adrenergic alpha-Antagonists↗

PubMed1987

Protein phosphorylation in rat pineal gland and its regulation in supersensitive and subsensitive states.

The phosphorylation of specific proteins in pineal homogenate was analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and autoradiography. Cyclic AMP had the capacity to stimulate in a dose-dependent manner the incorporation of 32P in protein bands of apparent molecular weights 59K, 56K, and 35K with a maximal effect at 1 microM. On the other hand, calcium alone did not induce a marked increase in 32P incorporation with the exception of a dose-dependent phosphorylation of a 46K protein with a peak effect at 0.2 mM calcium concentration. The addition of exogenous calmodulin enhanced 32P incorporation in proteins migrating in the 62K and 52K regions, an effect that was antagonized by the calmodulin inhibitor trifluoperazine. However, also under these conditions, the stimulation of pineal protein phosphorylation was rather weak compared to that observed in other brain areas. In an attempt to investigate the functional changes of these biochemical processes during environmental lighting and adrenergic stimulation, it was found that the administration of (-)-isoproterenol (5 mg/kg, s.c.), a beta-receptor agonist, induced a clear-cut enhancement of 32P incorporation into the cyclic AMP-sensitive 59K and 56K proteins only in animals exposed for 18 h to the light, whereas it was almost ineffective in those kept in the dark for the same period. This effect was antagonized by (-)-propranolol pretreatment (20 mg/kg), suggesting that the changes in cyclic AMP-dependent protein phosphorylation observed in supersensitive pineals may represent a beta-receptor mediated process.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗