Investigation on the presence of mycotoxins in seed hemp varieties

In recent years, the cultivation of hemp (Cannabis sativa L.) in Europe has aroused interest among farmers for the potential market opportunities of its products; its cultivation has increased from 20,450 ha in 2015 to 33,020 ha in 2022. Thanks to the great versatility of this crop, there are opportunities in the food and nutraceutical fields (gluten free), cosmetics, energy and industrial sectors. As for several crops, hemp seeds may also be contaminated by fungal pathogens compromising its quality and safety. Considering the recent interest of consumers in using hemp for food purposes, in the present work, a small survey on mycotoxin contamination was carried out during 2018-2022 in hemp seed samples cultivated in Italy for food use. The results showed a limited occurrence of the most common regulated mycotoxins (aflatoxins [AFs], fumonisins [FBs], ochratoxin A [OTA], deoxynivalenol [DON] and zearalenone), but very high levels of alternariols, reaching a maximum value of 38510, 308, 226 and 288 ug/kg for tenuazonic acid [TeA], tentoxin [TEN], alternariol [AOH] and alternariol monoether, respectively. In the same period, an investigation carried out in an experimental field showed that fungal contamination and mycotoxin occurrence were influenced by different meteorological conditions and different varieties.

Eu- or hypoglycemic ketosis and ketoacidosis in children: a review

The last decade has been characterized by exciting findings on eu- or hypoglycemic ketosis and ketoacidosis. This review emphasizes the following five key points: 1. Since the traditional nitroprusside-glycine dipstick test for urinary ketones is often falsely negative, the blood determination of β-hydroxybutyrate, the predominant ketone body, is currently advised for a comprehensive assessment of ketone body status; 2. Fasting and infections predispose to relevant ketosis and ketoacidosis especially in newborns, infants, children 7 years or less of age, and pregnant, parturient, or lactating women; 3. Several forms of carbohydrate restriction (typically less than 20% of the daily caloric intake) are employed to induce ketosis. These ketogenic diets have achieved great interest as antiepileptic treatment, in the management of excessive body weight, diabetes mellitus, and in sport training; 4. Intermittent fasting is more and more popular because it might benefit against cardiovascular diseases, cancers, neurologic disorders, and aging; 5. Gliflozins, a new group of oral antidiabetics inhibiting the renal sodium-glucose transporter 2, are an emerging cause of eu- or hypoglycemic ketosis and ketoacidosis. In conclusion, the role of ketone bodies is increasingly recognized in several clinical conditions. In the context of acid-base balance evaluation, it is advisable to routinely integrate both the assessment of lactic acid and β-hydroxybutyrate.

Disrupted Seasonality of Respiratory Viruses: Retrospective Analysis of Pediatric Hospitalizations in Italy from 2019 to 2023

This multicenter study in Italian hospitals highlights the epidemiologic disruptions in the circulation of the 5 main respiratory viruses from 2019 to 2023. Our data reveal a resurgence of respiratory syncytial virus and influenza during the 2022-2023 winter season, with an earlier peak in cases for both viruses, emphasizing the importance of timely monitoring.

A systematic review and meta-analysis on nutritional and dietary interventions for the treatment of acute respiratory infection in pediatric patients: An EAACI taskforce

Acute respiratory infections are a major cause of morbidity and mortality in children worldwide. Dietary and nutritional interventions, including minerals and vitamin supplementation, have been explored as potential treatments for these infections. However, the evidence on their efficacy is limited and inconclusive. This systematic review and meta-analysis aim to provide a comprehensive summary of the available evidence on the effectiveness of dietary and nutritional interventions for treating acute respiratory tract infections in children. A systematic review was conducted according to the PRISMA 2020 guidelines in April 2022 and updated in April 2023. Clinical trials focusing on dietary or nutritional interventions, including supplementations, in children with acute respiratory tract infections were included. The selection of interventions and outcomes was based on biological plausibility. Data were extracted using a standardized form, and the risk of bias was assessed using the Cochrane Risk of Bias Tool. Meta-analysis was performed using random-effect models. A total of 50 studies were included in the review. Four trials were conducted in low, 32 in lower-middle, 12 in upper-middle, and only two in high-income countries. The studies evaluated various dietary interventions, including zinc, vitamin A, vitamin E, vitamin D, and probiotics. The results of individual studies on the efficacy of these interventions were mixed, with some showing positive effects on clinical outcomes such as duration of symptoms, while others showed no significant impact. Meta-analysis was conducted for zinc supplementation in children with pneumonia, and the pooled results suggested a potential limited benefit in terms of reduced hospital length of stay but not time to recovery. Meta-analyses on vitamin D did not show any effect in children with pneumonia. This systematic review fills a critical gap in the literature by synthesizing the available evidence on the efficacy and safety of nutritional or dietary interventions for acute respiratory tract infections in children. The findings indicate no dietary or nutritional intervention can currently be recommended for the routine treatment of respiratory tract infections in children based on single supplement studies. The metanalysis suggests that zinc supplementation might have a beneficial effect on length of hospitalization in children with pneumonia. New studies are needed to establish more conclusive evidence for pediatric acute respiratory diseases especially for children living in a context of high-income countries.

Nationwide survey on the management of pediatric pharyngitis in Italian emergency units

BACKGROUND

Acute pharyngitis is a frequent reason for primary care or emergency unit visits in children. Most available data on pharyngitis management come from primary care studies that demonstrate an underuse of microbiological tests, a tendency to over-prescribe antibiotics and a risk of antimicrobial resistance increase. However, a comprehensive understanding of acute pharyngitis management in emergency units is lacking. This study aimed to investigate the frequency of rapid antigen test use to diagnose acute pharyngitis, as well as other diagnostic approaches, the therapeutic attitude, and follow-up of children with this condition in the emergency units.

METHODS

A multicentric national study was conducted in Italian emergency departments between April and June 2022.

RESULTS

A total of 107 out of 131 invited units (response rate 82%), participated in the survey. The results showed that half of the units use a scoring system to diagnose pharyngitis, with the McIsaac score being the most commonly used. Most emergency units (56%) were not provided with a rapid antigen diagnostic test by their hospital, but the test was more frequently available in units visiting more than 10,000 children yearly (57% vs 33%, respectively, p = 0.02). Almost half (47%) of the units prescribe antibiotics in children with pharyngitis despite the lack of microbiologically confirmed cases of Group A β-hemolytic streptococcus. Finally, about 25% of units prescribe amoxicillin-clavulanic acid to treat Group A β-hemolytic streptococcus pharyngitis.

CONCLUSIONS

The study sheds light on the approach to pharyngitis in emergency units, providing valuable information to improve the appropriate management of acute pharyngitis in this setting. The routinary provision of rapid antigen tests in the hospitals could enhance the diagnostic and therapeutic approach to pharyngitis.

Childhood fever and medical students: A multicentre, educational intervention

AIM

Misconceptions and non-evidence-based practices toward childhood fever are reported worldwide. Medical students might be ideal candidates to introduce long-lasting changes in clinical practice. However, no study has gauged the effectiveness of an educational intervention to improve fever management in this population. We conducted an educational, interventional study on childhood fever among final-year medical students.

METHODS

We conducted a prospective, multicentre interventional study employing a pre/post-test design. Participants from three Italian Universities filled in a questionnaire just before the intervention (T0), immediately after (T1) and 6 months later (T2) in 2022. The intervention was a two-hour lecture focused on the pathophysiology of fever, recommendations for its treatment and risks associated with improper management.

RESULTS

188 final-year medical students (median age of 26 years, 67% females) were enrolled. Relevant improvements in the criterion for treating fever and conceptions about the beneficial effects of fever were observed at T1 and T2. Similar data were found for the reduction of physical methods advice to decrease body temperature and concerns for brain damage from fever.

CONCLUSION

This study shows for the first time that an educational intervention is effective in changing students' conceptions and attitudes toward fever both in the short and medium term.

Effects of vitamin D supplementation in obese and overweight children and adolescents: a systematic review and meta-analysis

Due to the lipophilic nature of vitamin D, overweight and obese patients have an increased risk of inadequate circulating 25-hydroxy-vitamin D (25(OH)D) concentrations. Vitamin D deficiency has in turn several consequences especially among children and adolescents. Therefore, a few supplementation strategies of vitamin D for pediatric subjects with an excessive body weight have been proposed, but their efficacy remains controversial. The aim of this systematic review and meta-analysis is to evaluate the effect of vitamin D supplementation in overweight and obese children and adolescents. Three databases (PubMed, Embase and Web of Science) were searched to collect randomized controlled trials on the effect of vitamin D supplementation in the pediatric overweight or obese population. Twenty-three studies were included in the systematic review. Results on modification of metabolic or cardiovascular outcomes were controversial. On the other hand, the meta-analysis showed a mean difference by 1.6ng/mL in subjects supplemented with vitamin D as compared to placebo. In conclusion, vitamin D supplementation slightly increases 25(OH)D levels in pediatric subjects with overweight and obesity. However, the effects on metabolic and cardiovascular outcomes remain controversial. New efforts should be devoted to promoting effective interventions to improve the health of children and adolescents with overweight and obesity.

Analysis of Sequence Variability and Transcriptional Profile of Cannabinoid synthase Genes in Cannabis sativa L. Chemotypes with a Focus on Cannabichromenic acid synthase

Cannabis sativa L. has been long cultivated for its narcotic potential due to the accumulation of tetrahydrocannabinolic acid (THCA) in female inflorescences, but nowadays its production for fiber, seeds, edible oil and bioactive compounds has spread throughout the world. However, some hemp varieties still accumulate traces of residual THCA close to the 0.20% limit set by European Union, despite the functional gene encoding for THCA synthase (THCAS) is lacking. Even if some hypotheses have been produced, studies are often in disagreement especially on the role of the cannabichromenic acid synthase (CBCAS). In this work a set of European Cannabis genotypes, representative of all chemotypes, were investigated from a chemical and molecular point of view. Highly specific primer pairs were developed to allow an accurate distinction of different cannabinoid synthases genes. In addition to their use as markers to detect the presence of CBCAS at genomic level, they allowed the analysis of transcriptional profiles in hemp or marijuana plants. While the high level of transcription of THCAS and cannabidiolic acid synthase (CBDAS) clearly reflects the chemical phenotype of the plants, the low but stable transcriptional level of CBCAS in all genotypes suggests that these genes are active and might contribute to the final amount of cannabinoids.

Comparative genomics of geographically distant Fusarium fujikuroi isolates revealed two distinct pathotypes correlating with secondary metabolite profiles

Fusarium fujikuroi causes bakanae ("foolish seedling") disease of rice which is characterized by hyper-elongation of seedlings resulting from production of gibberellic acids (GAs) by the fungus. This plant pathogen is also known for production of harmful mycotoxins, such as fusarins, fusaric acid, apicidin F and beauvericin. Recently, we generated the first de novo genome sequence of F. fujikuroi strain IMI 58289 combined with extensive transcriptional, epigenetic, proteomic and chemical product analyses. GA production was shown to provide a selective advantage during infection of the preferred host plant rice. Here, we provide genome sequences of eight additional F. fujikuroi isolates from distant geographic regions. The isolates differ in the size of chromosomes, most likely due to variability of subtelomeric regions, the type of asexual spores (microconidia and/or macroconidia), and the number and expression of secondary metabolite gene clusters. Whilst most of the isolates caused the typical bakanae symptoms, one isolate, B14, caused stunting and early withering of infected seedlings. In contrast to the other isolates, B14 produced no GAs but high amounts of fumonisins during infection on rice. Furthermore, it differed from the other isolates by the presence of three additional polyketide synthase (PKS) genes (PKS40, PKS43, PKS51) and the absence of the F. fujikuroi-specific apicidin F (NRPS31) gene cluster. Analysis of additional field isolates confirmed the strong correlation between the pathotype (bakanae or stunting/withering), and the ability to produce either GAs or fumonisins. Deletion of the fumonisin and fusaric acid-specific PKS genes in B14 reduced the stunting/withering symptoms, whereas deletion of the PKS51 gene resulted in elevated symptom development. Phylogenetic analyses revealed two subclades of F. fujikuroi strains according to their pathotype and secondary metabolite profiles.

First Report of Fusarium andiyazi Associated with Rice Bakanae in Italy

Rice (Oryza sativa L.) is cultivated on approximately 230,000 ha in northern Italy. Since 2001, increasing economical losses presumably caused by Fusarium fujikuroi Nirenberg (Gibberella fujikuroi mating population C), an exotic fungus known as the etiological agent of Bakanae disease, have been reported in Italy. The spread of this disease is primarily seedborne. In 2009, during an annual survey of Italian rice seed, 69 samples were tested for the presence of strains belonging to the G. fujikuroi species complex. Four hundred seeds per sample were surface sterilized and then placed in 90-mm Petri dishes containing potato dextrose agar and incubated for 7 days at 21°C. Thirty two putative G. fujikuroi strains were single-spore purified and identified on the basis of their morphological features on Spezieller Nährstoffarmer agar plates with a piece of sterile filter paper. Strains were characterized at species level by morphological observations (1,2) and translation elongation factor 1-α (TEF) gene sequencing. Unexpectedly, 60% of the strains evaluated belonged to the species F. andiyazi Marasas, Rheeder, Lampr., K.A. Zeller & J.F. Leslie. This fungus, first described on sorghum (Sorghum bicolor L.) in Africa and the United States (1), has been reported to be one of the species associated with Bakanae in Asia and Africa (3). Two F. andiyazi strains, (E432 and E439), isolated in the district of Modena were chosen for pathogenicity testing and their TEF gene sequences were deposited in GenBank (Accession Nos. GU827420 and GU827419). A conidial suspension was produced on Mung-bean liquid media and adjusted to a concentration of 1 × 10⁶ CFU/ml. Italian cv. Galileo was used in the test because of its high susceptibility to Bakanae (Ente Nazionale delle Sementi Elette, Verona, Italy, data unpublished). Rice seeds were heat sterilized for 20 min at 60°C, submerged for 30 min in the conidial suspensions, dried, and subjected to a blotter test. Uninoculated, sterilized seeds served as a control. Seeds were incubated for 15 days in a growth chamber (26°C, 80% relative humidity, and 12-h photoperiod). For each strain, the experiment was repeated three times on samples of 25 seedlings. Results were analyzed by analysis of variance and Tukey test. Symptoms consisted of a generic seedling wilt, a root length reduction ranging from 21 to 48%, and the presence of root discoloration. Seed germination was reduced by 9%. Shoot development was not significantly altered. Proof of pathogenicity was obtained through reisolation of F. andiyazi from symptomatic tissues. To our knowledge, this is the first report of F. andiyazi on rice in Europe. References: (1) W. F. O. Marasas et al. Mycologia 93:1203, 2001. (2) H. I. Niremberg and K. O'Donnell. Mycologia 90:434, 1998. (3) E. G. Wulff et al. Environ. Microbiol. 12:649, 2009.

5-hydroxytryptamine (5-HT)1A autoreceptor adaptive changes in substance P (neurokinin 1) receptor knock-out mice mimic antidepressant-induced desensitization

Antagonists at substance P receptors of the neurokinin 1 (NK1) type have been shown to represent a novel class of antidepressant drugs, with comparable clinical efficacy to the selective serotonin (5-HT) reuptake inhibitors (SSRIs). Because 5-HT(1A) receptors may be critically involved in the mechanisms of action of SSRIs, we examined whether these receptors could also be affected in a model of whole-life blockade of NK1 receptors, i.e. knock-out mice lacking the latter receptors (NK1-/-). 5-HT(1A) receptor labeling by the selective antagonist radioligand [(3)H]N-[2-[4-(2-methoxyphenyl)1-piperazinyl]-ethyl]-N-(2-pyridinyl)-cyclohexanecarboxamide (WAY 100635) and 5-HT(1A)-dependent [(35)S]GTP-gamma-S binding at the level of the dorsal raphe nucleus (DRN) in brain sections, as well as the concentration of 5-HT(1A) mRNA in the anterior raphe area were significantly reduced (-19 to -46%) in NK1-/- compared with NK1+/+ mice. Furthermore, a approximately 10-fold decrease in the potency of the 5-HT(1A) receptor agonist ipsapirone to inhibit the discharge of serotoninergic neurons in the dorsal raphe nucleus within brainstem slices, and reduced hypothermic response to 8-OH-DPAT, were noted in NK1-/- versus NK1+/+ mice. On the other hand, cortical 5-HT overflow caused by systemic injection of the SSRI paroxetine was four- to sixfold higher in freely moving NK1-/- mutants than in wild-type NK1+/+ mice. Accordingly, the constitutive lack of NK1 receptors appears to be associated with a downregulation/functional desensitization of 5-HT(1A) autoreceptors resembling that induced by chronic treatment with SSRI antidepressants. Double immunocytochemical labeling experiments suggest that such a heteroregulation of 5-HT(1A) autoreceptors in NK1-/- mutants does not reflect the existence of direct NK1-5-HT(1A) receptor interactions in normal mice.

Assessment of topical bioavailability in vivo: the importance of stratum corneum thickness

We present a method to determine the cutaneous bioavailability and hence to evaluate the bioequivalence of topically applied drugs in vivo. The procedure uses serial tape-stripping and transepidermal water loss measurements to quantify the thickness of the removed stratum corneum (SC) and to determine the intact membrane thickness. Following tape-stripping, the drug is extracted from the tapes and assayed, e.g., by HPLC. This provides a drug concentration profile as a function of the normalized position within the SC. The data are fitted to a solution of Fick's second law of diffusion in order to calculate characteristic membrane transport parameters. Integration of the concentration profile over the entire SC thickness, that is, the 'area-under-the-curve', provides a measure of the cutaneous bioavailability and hence can be used to assess the bioequivalence of topically applied drugs.

Effect of ethanol and isopropyl myristate on the availability of topical terbinafine in human stratum corneum, in vivo

PURPOSE

The objective of this study was to determine the availability of the topical drug terbinafine (TBF) in human stratum corneum (SC) in vivo following its administration in formulations containing isopropyl myristate and ethanol.

METHODS

The ventral forearms of human volunteers were treated for 4 h with TBF, at a concentration equal to 1/4 saturation, in isopropyl myristate (IPM), in ethanol (EtOH) and in 50:50 v/v IPM/EtOH. At the end of the application period, the treated sites were carefully cleaned of excess vehicle and the SC was progressively removed by sequential tape stripping. TBF was quantified in the SC by: (a) extraction of the tape strips and subsequent HPLC analysis; and (b) attenuated total reflectance infrared spectroscopy (ATR-FTIR) of each sequentially exposed SC surface during the tape stripping procedure.

RESULTS

The concentration profile of TBF in the SC (i.e. drug concentration as a function of depth in the membrane) was fitted to the appropriate solution of Fick's second law of diffusion, allowing thereby the drug's SC/vehicle partition coefficient (K) and characteristic diffusion parameter (D/L(2), where D is the diffusivity of TBF in the SC of thickness L) to be deduced.

CONCLUSIONS

While D/L(2) for TBF derived from the three vehicles remained essentially constant, the drug's partitioning into the SC was significantly higher from formulations containing ethanol. Both the semi-quantitative infrared data and the more rigorous HPLC results supported these deductions.

In vivo assessment of enhanced topical delivery of terbinafine to human stratum corneum

PURPOSE

The objective of this study was to evaluate, using attenuated total reflectance Fourier transform infrared spectroscopy, the stratum corneum (SC) bioavailability of terbinafine (TBF) following topical treatment with four different formulations.

METHODS

Four skin sites on the ventral forearms of five healthy volunteers were treated for 2 h using one of four formulations based on a vehicle consisting of 50% ethanol and 50% isopropyl myristate. Three of these formulations included a percutaneous penetration enhancer: either 5% oleic acid, 10% 2-pyrrolidone or 1% urea. The SC concentration profile of TBF was measured by repeated infrared spectroscopic measurements while sequentially stripping off the layers of this barrier membrane with adhesive tape. This method was validated by HPLC analysis of TBF extracted from the stripped tapes. Transepidermal water loss (TEWL) measurements were also performed, to permit facile estimation of SC thickness.

RESULTS

The SC concentration profiles of TBF were fitted to the appropriate solution of Fick's second law of diffusion, thereby allowing determination of the characteristic diffusion and partitioning parameters of the permeating drug. This analysis enabled the efficacies of the different formulations tested to be compared to the no-enhancer control. While it was found that the formulation containing 5% oleic acid significantly enhanced the SC availability of TBF, the other formulations did not improve the apparent drug delivery.

CONCLUSIONS

A facile and minimally invasive methodology to evaluate an important aspect of topical drug bioavailability has been described. The analytical methods used (infrared spectroscopy and HPLC) allow estimates of both relative and absolute drug bioavailability in the SC and may be useful, therefore, in the critical determination of bioequivalence between topical formulations.

Changes in the expression of cytokeratins and nuclear matrix proteins are correlated with the level of differentiation in human prostate cancer

The nuclear matrix-intermediate filament complex (NM-IF) is a protein scaffold which spans the whole cell, and several lines of evidence suggest that this structural frame represents also a functional unit, which could be involved in the epigenetic control of cancer development. Here we report the characterization by high resolution two-dimensional gel electrophoresis and Western blot analysis of the NM-IF complex isolated from prostate cancer (PCa); tumor-associated proteins were identified by comparing the electrophoretic patterns with those of normal human prostate (NHP). Extensive changes in the expression of both the NM and IF proteins occur; they are, however, related in a different way to tumor progression. Poorly differentiated PCa (Gleason score 8-9) shows a strong down regulation of several constitutive cytokeratins (CKs 8, 18, and 19); their expression significantly (P < 0.05) decreases with respect to both NHP and benign prostatic hyperplasia (BPH) and, more interestingly, also with respect to moderately (Gleason score 6-7) and well (Gleason score 4-5) differentiated tumors. Moreover, we have identified a tumor-associated species which is present in all of the tumors examined, systematically absent in NHP and occurs only in a few samples of BPH; this polypeptide, of M(r) 48,000 and pI 6.0, represent a proteolytic fragment of CK8. At variance with these continuing alterations in the expression, the NM proteins undergo stepwise changes correlating with the level of differentiation. The development of less differentiated tumors is characterized by the appearance of several new proteins and by the decrease in the expression of others. Six proteins were found to be expressed with a frequency equal to one in poorly differentiated tumor, namely in all the samples of tumor examined, while in moderately and well differentiated tumors the frequency is less than one, and decreases with increasing the level of differentiation. When tumors of increasing Gleason score are compared with NHP a dramatic increase in the complexity of the protein patterns is observed, indicating that tumor dedifferentiation results in a considerable increase in the phenotypic diversity. These results suggest that tumor progression can be characterized using an appropriate subset of tumor-associated NM proteins.

CD99 (E2) up-regulates alpha4beta1-dependent T cell adhesion to inflamed vascular endothelium under flow conditions

CD99/E2 is an integral transmembrane protein which forms, together with Xga, a distinct family whose genes are located in the pseudoautosomal region. The number of T cells that firmly bound to vascular endothelial cells under physiological shear stress increased 2-14-fold upon CD99 stimulation, and bound cells became much more resistant to detachment forces and spread. T cell arrest occurred within 1 min and was dependent on the alpha4beta1-VCAM-1 pathway. In contrast, the alphaLbeta2-ICAM-1 pathway remained unactivated. This was observed with T cell lines and with activated peripheral blood lymphocytes, and was limited within the resting peripheral CD4+ T cells to the memory subset, while virgin cells were unaffected. This discloses a stepwise regulation of the T cell extravasation cascade.

Neonatal naltrindole and handling differently affect morphine antinociception in male and female rats

The effects of a daily injection of the delta selective opioid antagonist naltrindole (1 mg/kg), from birth to postnatal day 19, on antinociceptive responses to morphine (2 mg/kg) in 20-day-old rats of both sexes were investigated. The effects of postnatal handling were studied by including two control groups--one group receiving daily injections of saline, and a naive unhandled group. Antinociception was assessed using the tail-immersion test and time-response curves (5, 10, 15, and 30 min) were carried out for all experimental groups. In all treatment groups females showed greater sensitivity to the noxious stimuli compared to males. No significant effect of naltrindole treatment on baseline latencies was found. Postnatal handling increased sensitivity to thermal pain in both sexes, and reduced the effect of morphine in males. No significant effect of chronic naltrindole administration on morphine antinociception was found in this sex. Naltrindole-treated females showed an increased antinociception when compared to unhandled animals of the same gender. The results indicate that preweanling handling stress and chronic naltrindole treatment differentially affected morphine antinociception in male and female neonatal rats.

Chromatin condensation is confined to the loop and involves an all-or-none structural change

Using differential scanning calorimetry in combination with pulsed field gel electrophoresis, we relate here the changes in the thermal profile of rat liver nuclei induced by very mild digestion of chromatin by endogenous nuclease with the chain length distribution of the DNA fragments. The enthalpy of the endotherm at 106 degrees C, which reflects the denaturation of the heterochromatic domains, decreases dramatically after the induction of a very small number of double-strand breaks per chromosome; the thermal transition disappears when the loops have undergone on average one DNA chain scission event. Quantitative analysis of the experimental data shows that the loop behaves like a topologically isolated domain. Also discussed is the process of heterochromatin formation, which occurs according to an all-or-none mechanism. In the presence of spermine, a strong condensation agent, only the loops that have undergone one break are able to refold, in confirmation of the extremely cooperative nature of the transition. Furthermore, our results suggest a relationship between the states that give rise to the endotherms at 90 degrees C and 106 degrees C and the morphologies referred to as class II and class III in a previous physicochemical study of the folding of chromatin fragments (Widom, 1986. J. Mol. Biol. 190:411-424) and support the view that the overall process of condensation follows a sequential (two-step) pathway.

Chronic naltrindole administration does not modify the inhibitory effect of morphine on vocalization responses in the tail electric stimulation test in rats

To address the existence of possible functional interactions between delta- and mu- receptors in relation to the affective component of pain, we have studied the effects of functional blockade of delta-receptors by a chronic treatment with naltrindole (1 mg/kg, 8 consecutive days) on antinociceptive responses to morphine (2 and 5 mg/kg) in the tail electric stimulation test, in adult male rats. The thresholds for the motor response (tail withdrawal), vocalization during stimulus and vocalization afterdischarge were assessed. These responses are considered to be integrated at spinal, medulla oblongata and diencephalon-rhinencephalon levels, respectively. The results show that the vocalization during stimulus and the vocalization afterdischarge were significantly affected by morphine in a dose dependent manner, the latter response being the most sensitive to the effects of the mu-opioid agonist. However, no significant effect was observed on motor responses at the doses used in this study. Chronic naltrindole treatment did not modify the inhibitory effect of morphine on the vocalization responses. Since the vocalization afterdischarge is related to the affective component of pain, the data suggest that the delta-opioid receptor is not involved in the supraspinal mechanisms at which these responses are organized and that there is not a mu-delta interaction in the modulation of the affective responses to noxious electrical stimulation.

Naltrindole administration during the preweanling period and manipulation affect adrenocortical reactivity in young rats

The effect of a daily injection of the delta-selective opioid antagonist naltrindole (1 mg/kg), from birth to postnatal day 19, on basal and post-stress corticosterone levels in 25-day old rats of both sexes was investigated. The effects of manipulation were studied by including two control groups, one group received daily injections of saline and a second one was not manipulated. The stress protocol consisted of a 3 min swimming session in water at 20 degrees C. Corticosterone determinations were performed by radioimmunoassay. Control non-manipulated animals showed a significant increase in corticosterone levels in response to stress. Manipulation decreased basal hormone levels in females and prevented the stress-induced rise in corticosterone in males. Functional blockade of the delta-receptor during the preweanling period by the naltrindole treatment inhibited the corticosterone response to stress in females. The results indicate the existence of sex differences in the effects of manipulation on hypothalamus-pituitary-adrenal axis activity and the involvement of the delta-opioid receptor in the modulation of the adrenocortical response to stress during the postnatal period.

The condensation of chromatin in apoptotic thymocytes shows a specific structural change

Chromatin condensation and DNA cleavage at internucleosomal sites have been recognized early as hallmarks of apoptosis, and it has been suggested that extensive DNA chain scission could directly result in the formation of dense chromatin bodies. Here we have shown that no causal relationship exists between DNA degradation and chromatin condensation in glucocorticoid-induced thymocyte apoptosis. The chromatin rearrangement occurred independent of as well as prior to DNA cleavage and involved a specific conformational change at the nucleosome level. In the early stages of the process, the core particles appeared to be tightly packed face-to-face in smooth 11-nm filaments that progressively folded to generate a closely woven network. The network finally collapsed, producing dense apoptotic bodies. Since trypsin digestion relaxed condensed chromatin and histone H4 underwent appreciable deacetylation in the apoptotic cell, we suggest that changes in the DNA-histone interactions represented a major modulating factor of condensation.

Differential nuclear matrix-intermediate filament expression in human prostate cancer in respect to benign prostatic hyperplasia

We have characterized the changes in composition of the nuclear matrix-intermediate filament complex (NM-IF) isolated from prostate cancer (PCa), compared with benign prostatic hyperplasia (BPH). We prepared the NM-IF from ten patients undergoing radical retropubic prostectomy; the benign hyperplastic tissue was obtained from the prostate lobe contralateral to the cancer zone. Several quantitative and qualitative changes have been identified. Three new proteins of molecular weight 48, 47 and 29 kDa and isoelectric point 6.0, 4.9 and 6.4, respectively, were detected in PCa, referred to here as P8, P5 and NM-1, P8 was present in all ten of the tumors examined, P5 was expressed in 9/10 PCa; conversely, they were present in only one and two BPH, respectively; NM-1 was found in eight tumors out of nine and never in BPH. These proteins are expressed in moderately differentiated malignant cells, suggesting that the proteins of the NM-IF complex can be interesting biomarkers for prostate cancer. Immunoblot analysis shows that P8 and P5 proteins belong to the IF superfamily. This observation, taken together with previous data obtained by our and other groups, suggests that the characterization of NM-IF protein changes could also shed light on mechanistic aspects of cancer progression.

Changes in the cytoskeletal and nuclear matrix proteins in rat hepatocyte neoplastic nodules in their relation to the process of transformation

In a previous paper (Barboro et al., 1993, Biophys. J. 65, 1690-1699) we have shown that cancer development in the resistant hepatocyte model of Solt and Farber is characterized by the progressive unfolding of the higher-order structure of chromatin. A possible functional role of decondensation phenomena in cell transformation cannot be ruled out. Genetic activation involves the relaxation of the superstructure of chromatin, which may be, at least in part, modulated by its interaction with the nuclear matrix. Moreover, recent observations suggest that gene expression can be stimulated by alterations in the organization of the cytoskeleton. Therefore, we have characterized the changes in composition that the nuclear matrix-intermediate filament complex undergoes during the evolution of rat hepatocyte nodules. Dramatic changes in the expression of both the nuclear matrix and intermediate filament proteins occur during transformation; they are, however, related in a different way to the stages of carcinogenesis. Several new nuclear matrix proteins appear in early nodules, isolated 9 weeks after initiation. The subsequent evolution of persistent nodules is also characterized by discrete changes in the composition. Thus, the new synthesis of nuclear matrix proteins reflects the emergence of successive cellular populations, in line with the recent finding that a subset of components of the nuclear matrix is cell type-specific. In contrast, intermediate filament proteins undergo continuing changes. A new keratin with apparent molecular weight of 39 kDa, analogous to human keratin 19, appears in early nodules, and its expression steadily increases up to the 32nd week from initiation; at the same time, the amount of the proteolytic fragments of keratins A and D increases sharply. These findings suggest that the inappropriate expression of keratin 19 may be involved in the epigenetic activation of new cellular programs, through the rearrangement of the cytoskeleton which in turn may perturb nuclear matrix function.

Role of H1 in chromatin folding. A thermodynamic study of chromatin reconstitution by differential scanning calorimetry

In a series of related papers, we have recently presented the results of a thermodynamic approach to the conformational transitions of bulk chromatin induced in vitro by different structure-perturbing agents, such as the intercalating dye ethidium bromide or the ionic strength. In all these studies, we took advantage of the capability of differential scanning calorimetry to detect the changes in the melting behavior of the structural domains of chromatin (the linker and the core particle) associated with the order-disorder transitions. This technique also revealed that the higher-order structure undergoes a catastrophic decondensation process in the course of the transformation of rat hepatocytes as well as of cultured cells. Therefore, several questions arose concerning the biological function (if any) of the changes in the degree of condensation of bulk chromatin, as well as the mechanism of transition and the nature of the modulating agents. In this paper, we report a thermodynamic analysis of the reconstitution of H1-depleted calf thymus chromatin with the purpose of establishing (1) the binding mode of H1 and (2) the energetics and cooperativity of the transition from the unfolded to the condensed state. When H1 is progressively extracted from calf thymus nuclei by high-salt treatment, the endotherm at 107 degrees C, characteristic of the core particles interacting within condensed domains, converts into the thermal transition at 90 degrees C, resulting from the denaturation of noninteracting core particles. Binding of H1 fully restores the thermal profile of native chromatin. Analysis of H1 association shows that binding occurs at independent sites with KA = (3.67 +/- 0.60) x 10(4) M-1 and each site comprising 180 +/- 10 bp. The experimental dependence of the fraction of condensed chromatin on R, the moles of bound H1 per nucleosome mole, was compared with a simple thermodynamic model for the conformational change. This analysis yields a value of -5 kcal per nucleosome mole for the interaction free energy of nucleosomes within the ordered state. The process of condensation, is not, however, a highly cooperative (all-or-none) one, as expected from a consideration of the solenoidal model for the 30 nm fiber. Rather, nucleation of the helical state involves the face-to-face interaction between consecutive core particles, and the growth is largely determined by the mergence and rearrangement of neighboring clusters of helically arrayed nucleosomes.