[Comparison of methodologies to reach 'dry weight']. / Metodiche a confronto per il raggiungimento del peso secco.

BACKGROUND: In clinical practice it is very difficult to determine a final weight that is the expression of normovolemia. In hemodialysis (HD), 'dry weight' is conventionally defined as the weight reached by the patient at the end of that hemodialytic session when the maximum quantity of fluids is removed without inducing any symptomatology. The determination of dry weight has been based on the application of clinical criteria. The use of artificial kidneys with blood volume (BV) sensors has allowed the determination of dry weight through the interpretation of changes in the intradialytic BV curve. Conventional bioimpedance analysis (BIA), or better, the vectorial BIA (BIVA) is a new method for determining dry weight. This study evaluated the use of the above-mentioned method for the proper governing of dry weight. PATIENTS AND METHODS: Twenty HD patients were observed for 4 weeks. In the 1st week, the clinical symptomatology of every patient was monitored during both HD sessions and interdialytic periods. During the 2nd week, intradialytic changes in the BV of each patient were observed on artificial kidneys. In the 3rd week, a cardiologist monitored patients before and after hemodialytic treatments. In the 4th week, the body composition of each patient was analyzed through bioelectrical bioimpedance. RESULTS: Patients, who had clinically shown symptoms of hyperhydration, to the contrary at BIA were dehydrated. Conversely, patients who had dehydration symptoms presented signs of hyperhydration at BIA. CONCLUSIONS: BIVA is the diagnostic instrument that more accurately demonstrates the hydration state of hemodialytic patients. It contributes in defining dry weight more efficiently.

Acetylcholinesterase regeneration in mouse CNS studied by a microphotometric method.

Acetylcholinesterase (AChE) regeneration after single and repeated doses of diisopropylfluorophosphate (DFP) was investigated in neostriatum of central nervous system of Balb mice, by means of a microphotometric method. In the present study, three experimental groups received the following DFP treatments: group I was administered a single dose of 3 mg/kg; group II received weekly doses of 3 mg/kg for 9 weeks, and group III was exposed to 28 weekly treatments of 1 mg/kg, plus a last treatment of 3 mg/kg, for a total of 29 doses. The results of microphotometric analysis for all the experimental groups have shown a distinct reversibility pattern of DFP inhibition, consistent with the process of AChE regeneration. Nevertheless, one week following the last DFP treatment, a persisting difference (approximately 22%) in the AChE concentration between control and the experimental groups was observed. Based on our results and on the correlation reported in the literature between AChE reduction and muscarinic receptor density, the hazardous implications of organophosphate environmental contamination on human and animal health are pointed out.

The neuropathology of trimethyltin in the marmoset (Callithrix jacchus) hippocampal formation.

The effects of single and repeated doses of trimethyltin (TMT) treatment on the central nervous system (CNS) of the marmoset were investigated. For the acute-dose experiment adult animals were administered 3 mg/kg of TMT chloride (ip) and were then observed for changes in behavior. Within 24 hr postinjection all animals developed tremors, ataxia, and unresponsiveness. Half of the animals had severe clinical deterioration and died at 2 to 3 days following treatment. Surviving marmosets were sacrificed and the brain was subsequently perfusion-fixed for light microscopic examination. Neuronal degeneration was observed in many cells of the Ammon's horn and fascia dentata of the hippocampus. For the chronic-dose experiment, adult marmosets received (ip) weekly doses of 0.75 mg/kg of TMT chloride for 24 weeks. No evident clinical signs or behavioral changes were observed in any of the treated animals. Histological examination revealed neuropathological changes comparatively similar but less severe than those observed in the acute-treated animals. The differences in toxicity effects between acute and chronic TMT administration are compared and discussed.

Neuropathological and behavioral toxicology of trimethyltin exposure.

The most prominent neuropathological and behavioral changes induced by trimethyltin (TMT) in different mammalian species were reviewed. From the analysis of the reported literature it becomes evident that the neuropathological effects are selectively present in the limbic system structures. In particular, the granular neurons of the fascia dentata and the pyramidal cells of the Ammon's horn are involved, with a different pattern of severity and extension according to the various species studied and to the dosage-schedule used. The neurological damage produced by TMT to several limbic structures is related to overt behavioral changes. TMT acute exposure in adult rats produces a remarkable behavioral syndrome, consisting in tremors, spontaneous seizures, tail mutilation, vocalization, hyper-reactivity and intra-specific aggression. Impairments in learning and memory processes are also induced following acute treatment. Specific behavioral changes in various species reflect the different sensitivity and vulnerability to the chemical compounds. In addition, prenatal and postnatal exposure induce long-term behavioral and neurological effects on developing central nervous system.

The mossy fiber terminals in the hippocampal formation of Callithrix jacchus: comparative and evolutionary considerations.

The distribution of mossy fiber terminals in the regio inferior of the hippocampus of Callithrix jacchus was studied by means of Timm's method. The topographic distribution of Timm-positive zones in the hilus, in the suprapyramidal and intrapyramidal areas of the CA3 subfield is described. A Timm-positive reaction in intragranular strips and supragranular zones, the presence of Timm-negative zones in the infragranular border of the fascia dentata were found in this species. A comparison between mossy fiber distribution in Callithrix jacchus and that in human was carried out in an attempt to identify interspecies differences in the mossy fiber system in the hippocampus of primates. The hypothesis of a possible functional relevance of the supra- and intrapyramidal mossy fiber terminals on the control of hippocampal pyramidal neurons is expressed.

Distribution of carnosine-like immunoreactivity in the brain of the crested newt.

The distribution of the dipeptide carnosine was studied in the brain of the crested newt, Triturus carnifex, with immunohistochemical methods. Carnosine-like immunoreactivity (IR) is present in the cell bodies and processes of several areas of the central nervous system: in the telencephalon (especially in the medial pallium), in the diencephalon (pineal organ, thalamus, and hypothalamus), in the mesencephalon (optic tectum and tegmentum), and in the rhombencephalon (cerebellum, raphe region, and octavolateralis area). Double-labelling experiments show that carnosine IR is colocalized with tyrosine hydroxylase and neuropeptide Y IR in a few cells. Histochemical staining for heavy metals, the TIMM method, reveals that carnosine IR and TIMM labelling overlap in the medial pallium. These data indicate two primary conclusions: (a) In the crested newt brain, in contrast to those of mammals and birds, carnosine IR is not associated with glial cells but with neurons. Furthermore, carnosine is absent from the primary olfactory pathway in newts. (b) In the medial pallium of the crested newt, carnosine IR reliably identifies a population of neurons.

[Structural characteristics of the hippocampus in various strains of rats and mice]. / Osobennosti struktury gippokampa krys i myshei raznykh linii.

Original data together with those from literature are presented concerning structural peculiarities of the hippocamp in rats and mice. Structural differences are revealed not only in these species, but in separate strains from a single species. Fine structural differences may account for different modes of realization of the behavioural reaction.

Forebrain development in control and hypothyroid larvae of Triturus cristatus carnifex.

Some cytological and developmental aspects of the forebrain gray matter were studied in the control and the hypothyroid larvae of Triturus cristatus carnifex. The mitotic cell percentages in the periventricular germinal layer, the fusiform shape of the recently divided neuronal cells and the transitory gray matter cleavage, are characteristic of the immature status of the central nervous system (CNS) in this species. The hypothyroidism obtained during two months of thiourea treatment slows down the development in all the forebrain areas of the experimental larvae. Nevertheless, the nucleus olfactorius anterior and the corpus striatum, which have a longer mitotic activity with respect to the other neuronal structures, are more deeply affected by thyroid atrophy. Thyroid activity and forebrain maturation are discussed on the basis of the literature and our data with regard to their influence on behavior and evolution.

[The features of the hippocampal structure as a neuroanatomical basis for differences in behavior]. / Nekotorye osobennosti v strukture gippokampa kak neiroanatomicheskaia osnova razlichii v povedenii.

Neuromorphological and behavioural studies have been made on several strains of mice (C57B1, DBA/2, SEC) and on the spiny mouse Acomys cahirinus. It was shown that animals with different genotypes differ by the size of fascia dentata and by the extension of the pyramidal layer in CA3 field of the hippocamp. Animals with a higher learning capacity exhibited smaller layer of granular cells in the fascia dentata, which may be due to a lower density of neurones in this region. Terminals of the mossy fibers--the axons of granular cells--were found mainly on the apical dendrites of the pyramidal cells in CA3 field. On the contrary, in animals with lower capacities to learning, mossy fiber terminals were observed mainly on the basal dendrites of the pyramidal cells, the extent of the granular layer in these animals being significantly larger.

A genetic study of neostriatal cholinergic neurones in C57BL/6 and DBA/2 mice.

In the present study Butcher's pharmaco-histochemical technique for acetylcholinesterase has been employed for a morphometrical analysis of striatal cholinergic neurones in crossbred C57BL/6 x DBA/2 F1 mice. The general organization of neostriatal cholinergic systems in hybrid mice was similar to that of parent strains. However, as shown by morphometry, the size of neostriatum in hybrids was larger than that of both parental strains, and the density of striatal cholinergic neurones was significantly lower than that of DBA/2 mice, being close to that of the C57BL/6 strain. The present data indicate that a reduced number of striatal cholinergic neurones is inherited as a dominant trait by these hybrid mice.

[Comparative study of the brain of developed and underdeveloped neonatal rodents of the Muridae family]. / Sravnitel'noe issledovanie mozga u zrelo- i nezrelorozhdaiushchikhsia gryzunov iz semeistva myshinykh.

Morphological studies have been made of the neocortical and archicortical structures in the spiny mouse Acomys cahirinus, the only maturely born species from the family Muridae. The data obtained reveal highly developed hippocampus as compared to the neocortex in this mouse, in contrast to relationships found in other mice and rats.

Quantitative pharmacohistochemistry of acetylcholinesterase in neostriatum of inbred strains of mice.

A quantitative pharmacohistochemical technique has been used in the present study to assay acetylcholinesterase (AChE) activity in the neostriatum of C57BL/6 and DBA/2 mice. This technique permits the measurement of enzyme activity into microscopically defined compartments and is suitable for the study of striatal AChE-containing, putatively cholinergic, neurons. Microphotometric measurements have been performed in the cytoplasm of AChE-containing perikarya and in the striatal matrix: in both compartments, AChE activity was significantly higher in DBA/2 than in C57BL/6 mice. The present data show that AChE quantitative pharmacohistochemistry is suitable for studying the enzyme activity in nervous tissue and, particularly, in the cytoplasm of individual AChE-containing neurons. In addition, interstrain comparison indicates the presence of a genetically determined higher AChE content in striatal neurons of the DBA/2 strain.

A comparative study of mossy fiber distribution in the brain of the precocial Acomys cahirinus and of the altricial Rattus norvegicus: neuroanatomical bases and behavioral correlates.

Acomys cahirinus, the spiny mouse, is the only precocial murid. Given the relatively advanced state of neural maturation at birth, this species is therefore of interest for comparative studies of brain and behavioural development. Previous work on this species has indicated that (i) hippocampal thickness (relative to body weight) is greater in adult Acomys than in rats and mice; (ii) the hippocampus appears laminated at birth, unlike that of related altricial species; (iii) the degree of olfactory bulb maturation at birth is greater in Acomys than in gerbils or rats. In the study reported, the distribution of hippocampal mossy fibers of Acomys was compared with that of Rattus norvegicus, in order to extend our earlier findings. In addition, the implied involvement of hippocampal mossy fibers in olfaction suggests a relation to our studies of exploratory behaviour in this species.

Histochemical demonstration of heavy metals in the reptilian archicortex.

The topographic distribution of heavy metals has been studied in the reptilian brain by means of Timm's sulphide silver method. Timm-positive histochemical reaction was detected in the archicortex and in the septum. In the first region, the staining pattern yielded evidence of cortical layering and the distribution of mossy fiber terminals. In the septum, uneven distribution of histochemical staining permitted identification of different functional territories. These data show that the reptilian archicortex is in many ways homologous to the mammalian hippocampus and fascia dentata, and also indicate that it undergoes significant remodeling during evolution.

Strain-dependent variations in the number of forebrain cholinergic neurons.

The morphological organization of putatively cholinergic neurons was studied in the forebrain of two inbred mouse strains (C57BL/6 and DBA/2) by means of acetylcholinesterase pharmacohistochemistry. In both strains, putatively cholinergic perikarya were seen in the caudato-putamen, medial septum, diagonal band, and basal nucleus of Meynert: in all these regions, their distribution was similar in both strains, but their density was significantly higher (from 20 to 32%) in DBA/2 mice. The present data demonstrate the existence of genetically determined differences in the organization of forebrain cholinergic systems.

Transneuronal degeneration in different inbred strains of mice: a preliminary study of olfactory bulb events after olfactory nerve lesion.

Cytological analysis of the olfactory bulb was performed in two inbred strains of mice SEC/1 ReJ and C57/B16J after the lesion of the olfactory nerve. The data show an enhanced transneural degeneration in C57 mice as compared to the controls, while in the SEC mice this phenomenon did not exceed the level of spontaneous degeneration previously described by other authors. On the basis of our findings two different genetically adaptive systems are hypothesized and correlated with onto-genetical data.

Archicortex and neocortex in the precocial murid Acomys cahirinus. A comparison with two altricial species: Mus musculus and Rattus norvegicus.

A morphological analysis of some structures of the archicortex and neocortex was performed in the Acomys cahirinus (spiny mouse), the only precocial murid. The data obtained indicate that the spiny mouse brain is an interesting case of a largely developed hippocampus with respect to the neocortex when compared to the brains of the mouse and rat. The precocious pups of the spiny mouse present the peculiarity among Murids of an early olfactory imprinting.