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Biomedical subjects

D Carpi

Publications and source records attributed to D Carpi.

9 recordsLinked to original sources
PubMed2000

Macrolide resistance in group A streptococci.

Two hundred and twenty one Streptococcus pyogenes isolates collected from throat swabs of untreated children with uncomplicated pharyngotonsillitis living in two centres situated in the north of Italy were tested to evaluate their macrolide resistance phenotype. Isolates were also typed for T protein and assayed for opacity factor (OF) and protease production. Resistance to macrolides was found to be similar in the two centres. Fifty-one point two per cent of Torino strains and 43.5% of Pinerolo strains were not inhibited by erythromycin. Resistant strains belonged to one of three phenotypes: CR, constitutive resistance (37.9 and 42.5% in Torino and Pinerolo, respectively); IR, inducible resistance (40.9 and 17. 5%); NR, new resistance phenotype (21.2 and 40%). All the resistant and some of the susceptible strains were analysed by pulsed-field gel electrophoresis and genomic patterns were defined on the basis of band size and number. Five DNA profiles were found among erythromycin-resistant strains: three patterns characterized the NR resistance phenotype and one each the IR and CR phenotypes. The distribution of resistant strains according to their genomic patterns appears to be related to the resistance phenotype and only in some cases to the T serotype of bacteria. We conclude that the S. pyogenes strains analysed are genetically heterogeneous and therefore the high rate of erythromycin resistance observed is not caused by the spread of a single clone nor is it related to a particular serotype.

Anti-Bacterial Agents↗
PubMed1999

Interactions between hippocampus and medial septum during sharp waves and theta oscillation in the behaving rat.

The medial septal region and the hippocampus are connected reciprocally via GABAergic neurons, but the physiological role of this loop is still not well understood. In an attempt to reveal the physiological effects of the hippocamposeptal GABAergic projection, we cross-correlated hippocampal sharp wave (SPW) ripples or theta activity and extracellular units recorded in the medial septum and diagonal band of Broca (MSDB) in freely moving rats. The majority of single MSDB cells (60%) were significantly suppressed during SPWs. Most cells inhibited during SPW (80%) fired rhythmically and phase-locked to the negative peak of the CA1 pyramidal layer theta waves. Because both SPW and the negative peak of local theta waves correspond to the maximum discharge probability of CA1 pyramidal cells and interneuron classes, the findings indicate that the activity of medial septal neurons can be negatively (during SPW) or positively (during theta waves) correlated with the activity of hippocampal interneurons. We hypothesize that the functional coupling between medial septal neurons and hippocampal interneurons varies in a state-dependent manner.

Afferent Pathways↗
PubMed1999

The entorhino-septo-supramammillary nucleus connection in the rat: morphological basis of a feedback mechanism regulating hippocampal theta rhythm.

Recent electrophysiological observations suggest that, in addition to the medial septal area pacemaker system, several alternative or additional mechanisms are involved in the generation/regulation of hippocampal theta activity. Discharging neurons phase-locked to hippocampal theta waves have been observed in the dorsal raphe, nucleus reticularis pontis oralis and especially in the supramammillary region of rats. Since these areas are reciprocally interconnected with the hippocampal formation, including the entorhinal cortex, it would aid our understanding of limbic function to elucidate the location and neurochemical content of the entorhino-septal and septo-supramammillary projection neurons, as well as that of their postsynaptic targets. Light and electron microscopic immunostaining for calretinin, in combination with antero- and retrograde tracer techniques, postembedding immunostaining for GABA and the transmitter specific [3H]D-aspartate retrograde radiolabeling, as well as a co-localization experiment for calretinin and glutamate decarboxylase in rat supramammillary and septal neurons, demonstrated that: (i) a large population of entorhinal cells that forms asymmetric synaptic contacts on calretinin-containing neurons located at the border between the medial and lateral septal areas contains calretinin and are aspartate/glutamatergic; (ii) the overwhelming majority of calretinin-immunoreactive cells located at the border between the lateral and medial septal area are GABAergic; (iii) these neurons can be retrogradely labeled from the supramammillary area; (iv) anterogradely labeled axons originating in the border between the medial and lateral septum are GABAergic and (v) terminate on supramammillary area non-GABAergic, calretinin-containing neurons, which are known to project to the septal complex and hippocampus. These observations indicate that a large population of cells participating in the hippocampal feedback regulation of theta regulation/generation contain the same calcium-binding protein. Furthermore, entorhinal excitatory transmitter-containing neurons can depress the activity of supramammillary theta generating/regulating cells via septal inhibitory neurons.

Animals↗
PubMed1997

[Not Available].

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Education, Medical↗
PubMed1996

Lack of hippocampal involvement in a rat model of petit mal epilepsy.

Although petit mal epilepsy is believed to arise from the thalamocortical system, it has been suggested recently that high-voltage spike-and-wave activity (HVS) in mutant mice can cause structural reorganization in the hippocampus, similar to that seen in temporal lobe epilepsy. We tested this assumption in rat strains with low and high incidence of HVS. No relationship was found between mossy fiber sprouting and HVS incidence. Hippocampal neurons were not driven by HVS. These findings suggest that petit mal seizures do not invade the hippocampus and are not causally related to sprouting of the mossy fibers.

Animals↗
PubMed1996

[Urinary tract infection prevention in catheterized patients. Prevalence National Study: preliminary studies at the Pinerolo Hospital].

Urinary tract infection incidence can be a possible indicator of the quality of health care in hospital. It is now clear that some kind of health care, practice and particular organizational and structural orders change the risk of UTI during hospitalizations. One third of hospital infections can be prevented by carrying out specified rules and guidelines. About 80% of UTI are a consequence of bladder catheterism. According to Major Health Institute, our Hospital takes part in a Study Group on the incidence and prevention of UTI related to bladder catheterism. Preliminary results show how much surgery activity still weighs in the cases of necessity of catheterism. Differently, urinary retention and incontinence and diuresis monitoring have a minor incidence. However the incidence of UTI after bladder catheterism is very high in our study (until 85%) also and hence the subsequent necessary antimicrobical therapy.

Cross Infection↗
PubMed1995

Genetic threshold hypothesis of neocortical spike-and-wave discharges in the rat: an animal model of petit mal epilepsy.

Neocortical high-voltage spike-and-wave discharges (HVS) in the rat are an animal model of petit mal epilepsy. Genetic analysis of total duration of HVS (s/12 hr) in reciprocal F1 and F2 hybrids of F344 and BN rats indicated that the phenotypic variability of HVS cannot be explained by a simple, monogenic Mendelian model. Biometrical analysis suggested the presence of additive, dominance, and sex-linked-epistatic effects, buffering maternal influence, and heterosis. High correlation was observed between average duration (s/episode) and frequency of occurrence of spike-and-wave episodes (n/12 hr) in parental and segregating generations, indicating that common genes affect both duration and frequency of the spike-and-wave pattern. We propose that both genetic and developmental-environmental factors control an underlying quantitative variable, which, above a certain threshold level, precipitates HVS discharges. These findings, together with the recent availability of rat DNA markers for total genome mapping, pave the way to the identification of genes that control the susceptibility of the brain to spike-and-wave discharges.

Action Potentials↗
PubMed1995

Spike-and-wave epilepsy in rats: sex differences and inheritance of physiological traits.

Spontaneously occurring spike-and-wave patterns were examined in seven to eight-month-old rats of the inbred Fischer 344 and Brown Norway strains and their F1 and F2 hybrids. Neocortical activity and movement were monitored for 12 night h. Spike-and-wave episodes were identified by a three-layer back-propagation neural network. The incidence, average duration and total duration of spike-and-wave episodes were significantly higher in F1 males and F2 hybrids than in the parental strains. Male rats of the Brown Norway strain had significantly more and longer episodes than females, whereas no sex differences were present in Fischer rats. The average intraepisodic frequency of spike-and-wave patterns was significantly lower in Fischer rats than in the other groups and significantly higher in males than females. Tremor (myoclonic movements) associated with spike-and-wave episodes was absent or of very small amplitude in Fischer rats but frequent and of large amplitude in Brown Norway rats and their F1 and F2 descendants. Most of the interstrain differences were limited to male rats. Spike-and-wave episodes recurred at predictable short-term (10-30 s) and long-term (15-30 min) periods. The long-term oscillation corresponded to a similar fluctuation of motor activity. The maximum probability of spike-and-wave patterns occurred at a relatively narrow range of delta power (0-3.1 Hz) of the background EEG activity. Systemic administration of the adrenergic alpha-2 agonist, clonidine, increased the incidence of spike-and-wave episodes several-fold. The total duration of spike-and-wave episodes in the clonidine sessions (15 min) and night sessions (12 h test) correlated significantly. We suggest that several genes interact with maturational, environmental and endocrine factors, resulting in sex differences, and produce the variety of EEG and behavioral findings encountered. In addition, we submit that the clonidine test may be useful in genetic investigations of human absence epilepsies. The findings of this work demonstrate that genetic manipulation of rodents is a promising method for producing analogous models for the various forms of human absence epilepsies.

Animals↗