Gestational and postnatal malnutrition affects sensitivity of young rats to picrotoxin and quinolinic acid and uptake of GABA by cortical and hippocampal slices

Seizures in eating disorders

OBJECTIVE

To complete a descriptive study of seizure etiology in a large population of eating disorder (ED) patients and to better understand whether malnutrition itself, in those with EDs, is associated with seizure development.

METHOD

In this retrospective study, 75 patients with documented seizures met inclusion criteria from a total of 1664 charts.

RESULTS

Prevalence of seizures in this ED cohort was found to be 4.5%, with 29.3% of individuals experiencing seizures due to psychogenic nonepileptic seizures (PNES). Other common causes of seizures included substance abuse/withdrawal (18.7%), primary seizure disorder (12%), and electrolyte abnormalities/hypoglycemia (10.7%). Three patients (4%) also developed their seizures presumably due to Wernicke's encephalopathy (WE).

DISCUSSION

Several etiologies of seizures are reported from this large sample of ED patients, and this is also the first study to report on a possible association of WE as a cause of seizures in ED patients. The contribution of WE and malnutrition toward the development of seizures in this population remains to be determined, and future studies should also seek to better understand the inter-relationship between malnutrition and the other variables discussed in this article, such as hypomagnesemia, toward seizure development.

PUBLIC SIGNIFICANCE

The medical complications of EDs are myriad but seizures have not historically been considered one of those direct complications of malnutrition. The findings of this retrospective study suggest that seizure development may be a direct and indirect complication associated with EDs. The presentation of Wernicke's encephalopathy, which can also be associated with development of seizures, requires further investigation in those with EDs.

7-Fluoro-1,3-diphenylisoquinoline-1-amine reverses the reduction in self-care behavior induced by maternal separation stress in rats by modulating glutamatergic/GABAergic systems

7-Fluoro-1,3-diphenylisoquinoline-1-amine (FDPI) is a promising isoquinoline that elicits an antidepressant-like action in rodents. In this study, an animal model of stress induced by maternal separation was used to investigate the effects of FDPI in Wistar rats of 30 and 90 days of age. It was investigated the effects of maternal separation in the self-care behavior and the contribution of glutamatergic and gamma-aminobutyric acid (GABA)ergic systems in the FDPI action. Male Wistar rats were separated from their mothers for 3 h/day from postnatal day (PND) 1-10. The rats were treated at different ages (PND-30 and PND-90) with FDPI (5 mg/kg, intragastrically/7 days) and performed the splash test. Maternal separation reduced total grooming time in the splash test, an index of motivational and self-care behavior, and FDPI treatment was effective in reversing this behavior in rats at both ages. The neurochemical parameters were differently affected, dependent on the age of rats, by maternal separation and FDPI. Maternal separation increased the GABA uptake and the excitatory amino acid transporter 1 levels in the prefrontal cortices of rats at PND-30 and FDPI was effective against these alterations. At PND-90, maternal separation decreased the glutamate uptake and increased the GABA uptake and the N-methyl-D-aspartate (NMDA) receptor 2B levels in the prefrontal cortices of rats. FDPI reversed the neurochemical alterations caused by maternal separation in the prefrontal cortices of rats at PND-90. The results of this study demonstrated that FDPI reversed the reduction in self-care behavior induced by maternal separation stress in rats by modulating the glutamatergic/GABAergic systems in rats.

Contribution of NMDA, GABAA and GABAB receptors and l-arginine-NO-cGMP, MEK1/2 and CaMK-II pathways in the antidepressant-like effect of 7-fluoro-1,3-diphenylisoquinoline-1-amine in mice

It has been reported that the antidepressant-like effect of 7-fluoro-1,3-diphenylisoquinoline-1-amine (FDPI) may result from the modulation of brain monoaminergic systems. However, the mechanisms of FDPI action are not fully understood. The aim of this study was to investigate the contribution of N-methyl-d-aspartate (NMDA) and gamma-aminobutyric acid (GABA) systems as well as l-arginine-nitric oxide-(NO)-cyclic guanosine monophosphate-(cGMP), mitogen-activated protein/extracellular signal-regulated kinase (MEK1/2) and Ca(2+)/calmodulin-dependent protein kinase II (CaMK-II) signaling pathways in the antidepressant-like effect of FDPI in the mouse forced swimming test (FST). The levels of NO and uptake of [(3)H]glutamate and [(3)H]GABA were determined in prefrontal cortices of Swiss mice. Pretreatments with NMDA (0.1 pmol/site, i.c.v., a NMDA receptor agonist), bicuculline (1mg/kg, i.p., a GABAA receptor antagonist), phaclofen (2mg/kg, i.p., a GABAB receptor antagonist) and l-arginine (750mg/kg, i.p., a NO precursor), KN-62 (1μg/site, a CaMK-II inhibitor), U0126 (5μg/site, a MEK1/2 inhibitor) and PD09058 (5μg/site, a MEK1/2 inhibitor) blocked the antidepressant-like effect of FDPI, at a dose of 1mg/kg, in the FST. ODQ (30 pmol/site, i.c.v., a soluble guanylate cyclase (sGC) inhibitor) in combination with a sub-effective dose of FDPI (0.1mg/kg, i.g.) reduced the immobility time in the FST. The administration of FDPI (50mg/kg) to mice increased the glutamate uptake and reduced NO levels in the prefrontal cortex of mice. The results suggest a contribution of NMDA, GABAA and GABAB receptors and l-arginine-NO-cGMP pathway in the antidepressant-like action of FDPI in mice, and this effect is related to CaMK-II and MEK 1/2 activation.

Enzyme Complexes Important for the Glutamate-Glutamine Cycle

Transient multienzyme and/or multiprotein complexes (metabolons) direct substrates toward specific pathways and can significantly influence the metabolism of glutamate and glutamine in the brain. Glutamate is the primary excitatory neurotransmitter in brain. This neurotransmitter has essential roles in normal brain function including learning and memory. Metabolism of glutamate involves the coordinated activity of astrocytes and neurons and high affinity transporter proteins that are selectively distributed on these cells. This chapter describes known and possible metabolons that affect the metabolism of glutamate and related compounds in the brain, as well as some factors that can modulate the association and dissociation of such complexes, including protein modifications by acylation reactions (e.g., acetylation, palmitoylation, succinylation, SUMOylation, etc.) of specific residues. Development of strategies to modulate transient multienzyme and/or enzyme-protein interactions may represent a novel and promising therapeutic approach for treatment of diseases involving dysregulation of glutamate metabolism.

Neonatal low-protein diet reduces the masticatory efficiency in rats

Little is known about the effects of undernutrition on the specific muscles and neuronal circuits involved in mastication. The aim of this study was to document the effects of neonatal low-protein diet on masticatory efficiency. Newborn rats whose mothers were fed 17% (nourished (N), n 60) or 8% (undernourished (U), n 56) protein were compared. Their weight was monitored and their masticatory jaw movements were video-recorded. Whole-cell patch-clamp recordings were performed in brainstem slice preparations to investigate the intrinsic membrane properties and N-methyl-d-aspartate-induced bursting characteristics of the rhythmogenic neurons (N, n 43; U, n 39) within the trigeminal main sensory nucleus (NVsnpr). Morphometric analysis (N, n 4; U, n 5) were conducted on masseteric muscles serial cross-sections. Our results showed that undernourished animals had lower numbers of masticatory sequences (P=0·049) and cycles (P=0·045) and slower chewing frequencies (P=0·004) (N, n 32; U, n 28). Undernutrition reduced body weight but had little effect on many basic NVsnpr neuronal electrophysiological parameters. It did, however, affect sag potentials (P<0·001) and rebound firing (P=0·005) that influence firing pattern. Undernutrition delayed the appearance of bursting and reduced the propensity to burst (P=0·002), as well as the bursting frequency (P=0·032). Undernourished animals showed increased and reduced proportions of fibre type IIA (P<0·0001) and IIB (P<0·0001), respectively. In addition, their fibre areas (IIA, P<0·001; IIB, P<0·001) and perimeters (IIA, P<0·001; IIB, P<0·001) were smaller. The changes observed at the behavioural, neuronal and muscular levels suggest that undernutrition reduces chewing efficiency by slowing, weakening and delaying maturation of the masticatory muscles and the associated neuronal circuitry.

Trypanosoma evansi infection impairs memory, increases anxiety behaviour and alters neurochemical parameters in rats

The aim of this study was to investigate neurochemical and enzymatic changes in rats infected with Trypanosoma evansi, and their interference in the cognitive parameters. Behavioural assessment (assessment of cognitive performance), evaluation of cerebral L-[3H]glutamate uptake, acetylcholinesterase (AChE) activity and Ca+2 and Na+, K+-ATPase activity were evaluated at 5 and 30 days post infection (dpi). This study demonstrates a cognitive impairment in rats infected with T. evansi. At 5 dpi memory deficit was demonstrated by an inhibitory avoidance test. With the chronicity of the disease (30 dpi) animals showed anxiety symptoms. It is possible the inhibition of cerebral Na+, K+-ATPase activity, AChE and synaptosomal glutamate uptake are involved in cognitive impairment in infected rats by T. evansi. The understanding of cerebral host–parasite relationship may shed some light on the cryptic symptoms of animals and possibly human infection where patients often present with other central nervous system (CNS) disorders.

Early protein malnutrition negatively impacts physical growth and neurological reflexes and evokes anxiety and depressive-like behaviors

Malnutrition is a worldwide problem affecting millions of unborn and young children during the most vulnerable stages of their development. In humans, poor maternal nutrition is a major cause of intrauterine growth restriction which is associated with an increased risk of perinatal mortality and long-term morbidity. In addition, intrauterine growth restriction correlates with neurodevelopmental delays and alterations of brain structure and neurochemistry. While there is no doubt that maternal malnutrition is a principal cause of perturbed development of the fetal brain and that all nutrients have certain influence on brain maturation, proteins appear to be the most critical for the development of neurological functions. In the present study we assessed male and female mouse offspring, born to dams protein restricted during pregnancy and lactation, in physical growth and neurobehavioral development and also in social interaction, motivation, anxiety and depressive behaviors. Moreover, we evaluate the impact of the low protein diet on dams in relation to their maternal care and anxiety-related behavior given that these clearly affect pups development. We observed that maternal protein restriction during pregnancy and lactation delayed the physical growth and neurodevelopment of the offspring in a sex-independent manner. In addition, maternal undernutrition negatively affected offspring's juvenile social play, motivation, exploratory activity and risk assessment behaviors. These findings show that protein restriction during critical periods of development detrimentally program progeny behavior.

Physiological slowing and upregulation of inhibition in cortex are correlated with behavioral deficits in protein malnourished rats

Protein malnutrition during early development has been correlated with cognitive and learning disabilities in children, but the neuronal deficits caused by long-term protein deficiency are not well understood. We exposed rats from gestation up to adulthood to a protein-deficient (PD) diet, to emulate chronic protein malnutrition in humans. The offspring exhibited significantly impaired performance on the 'Gap-crossing' (GC) task after reaching maturity, a behavior that has been shown to depend on normal functioning of the somatosensory cortex. The physiological state of the somatosensory cortex was examined to determine neuronal correlates of the deficits in behavior. Extracellular multi-unit recording from layer 4 (L4) neurons that receive direct thalamocortical inputs and layers 2/3 (L2/3) neurons that are dominated by intracortical connections in the whisker-barrel cortex of PD rats exhibited significantly low spontaneous activity and depressed responses to whisker stimulation. L4 neurons were more severely affected than L2/3 neurons. The response onset was significantly delayed in L4 cells. The peak response latency of L4 and L2/3 neurons was delayed significantly. In L2/3 and L4 of the barrel cortex there was a substantial increase in GAD65 (112% over controls) and much smaller increase in NMDAR1 (12-20%), suggesting enhanced inhibition in the PD cortex. These results show that chronic protein deficiency negatively affects both thalamo-cortical and cortico-cortical transmission during somatosensory information processing. The findings support the interpretation that sustained protein deficiency interferes with features of cortical sensory processing that are likely to underlie the cognitive impairments reported in humans who have suffered from prolonged protein deficiency.

m-Trifluoromethyl diphenyl diselenide attenuates glutaric acid-induced seizures and oxidative stress in rat pups: involvement of the γ-aminobutyric acidergic system

Glutaric acidemia type I (GA-I) is an inherited metabolic disease characterized by accumulation of glutaric acid (GA) and seizures. The intrastriatal GA administration in rats has been used as an animal model to mimic seizures presented by glutaric acidemic patients. m-Trifluoromethyl diphenyl diselenide, (m-CF(3) -C(6) H(4) Se)(2) , is an organoselenium compound that protects against seizures induced by pentylenetetrazole in mice. Thus, the aim of this study was to investigate whether (m-CF(3) -C(6) H(4) Se)(2) is effective against GA-induced seizures and oxidative stress in rat pups 21 days of age. Our findings demonstrate that (m-CF(3) -C(6) H(4) Se)(2) preadministration (50 mg/kg; p.o.) protected against the reduction in latency and the increased duration of GA (1.3 μmol/right striatum)-induced seizures in rat pups. In addition, (m-CF(3) -C(6) H(4) Se)(2) protected against the increase in reactive species generation and the reduction in antioxidant defenses glutathione peroxidase and glutathione S-transferase activities induced by GA. By contrast, no change in glutathione reductase or catalase activities was found. In addition, (m-CF(3) -C(6) H(4) Se)(2) was effective in protecting against inhibition of Na(+) ,K(+) -ATPase activity caused by GA in striatum of rat pups. This study showed for the first time that GA administration caused an increase in [(3) H]GABA uptake from striatum slices of rat pups and that (m-CF(3) -C(6) H(4) Se)(2) preadministration protected against this increase. A positive correlation between duration of seizures and [(3) H]GABA uptake levels was demonstrated. The results indicate that (m-CF(3) -C(6) H(4) Se)(2) protected against GA-induced seizures. Moreover, these findings suggest that the protection against oxidative stress, the inhibition of Na(+) ,K(+) -ATPase activity, and the increase in [(3) H]GABA uptake are possible mechanisms for the potential anticonvulsant action of (m-CF(3) -C(6) H(4) Se)(2).

Involvement of GABAergic and glutamatergic systems in the anticonvulsant activity of 3-alkynyl selenophene in 21 day-old rats

In this study, we investigated the role of GABAergic and glutamatergic systems in the anticonvulsant action of 3-alkynyl selenophene (3-ASP) in a pilocarpine (PC) model of seizures. To this purpose, 21 day-old rats were administered with an anticonvulsant dose of 3-ASP (50 mg/kg, per oral, p.o.), and [(3)H]γ-aminobutyric acid (GABA) and [(3)H]glutamate uptakes were carried out in slices of cerebral cortex and hippocampus. [(3)H]GABA uptake was decreased in cerebral cortex (64%) and hippocampus (58%) slices of 21 day-old rats treated with 3-ASP. In contrast, no alteration was observed in [(3)H]glutamate uptake in cerebral cortex and hippocampus slices of 21 day-old rats that received 3-ASP. Considering the drugs that increase synaptic GABA levels, by inhibiting its uptake or catabolism, are effective anticonvulsants, we further investigated the possible interaction between sub-effective doses of 3-ASP and GABA uptake or GABA transaminase (GABA-T) inhibitors in PC-induced seizures in 21 day-old rats. For this end, sub-effective doses of 3-ASP (10 mg/kg, p.o.) and DL-2,4-diamino-n-butyric acid hydrochloride (DABA, an inhibitor of GABA uptake--2 mg/kg, intraperitoneally; i.p.) or aminooxyacetic acid hemihydrochloride (AOAA; a GABA-T inhibitor--10 mg/kg, i.p.) were co-administrated to 21 day-old rats before PC (400 mg/kg; i.p.) treatment, and the appearance of seizures was recorded. Results demonstrated that treatment with AOAA and 3-ASP or DABA and 3-ASP significantly abolished the number of convulsing animals induced by PC. The present study indicates that 3-ASP reduced [(3)H]GABA uptake, suggesting that its anticonvulsant action is related to an increase in inhibitory tonus.

Executive functions of postweaning protein malnutrition in mice

It is well known that nutritional status during the fetal and/or lactation period is important for the development of the central nervous system (CNS). In contrast, the effect of malnutrition on postweaning development has not yet been thoroughly investigated. In the present study, we analyzed the behavioral and neuroanatomical effects of protein malnutrition (PM) postweaning in mice. Starting at 20-21 d of age, male ddY mice were maintained on a 5% casein diet (PM group) or 20% casein diet (control group) for 20 d. On the 20th d, body and brain weights of PM mice were lower than those of the control group. PM mice exhibited excessive alertness and spontaneous activity under novel conditions in the Irwin test. In addition, PM mice showed increased open arm exploration in the elevated plus maze compared to control mice. These results suggest that hyperactivity and reduced anxiety behavior or higher impulsiveness in PM mice could be due to an immature brain.

Effects of pre- and postnatal protein malnutrition in hypoxic-ischemic rats

Neonatal hypoxic-ischemic encephalopathy (HI) is a major cause of nervous system damage and neurological morbidity. Perinatal malnutrition affects morphological, biochemical and behavioral aspects of neural development, including pathophysiological cascades of cell death triggered by ischemic events, so modifying resulting brain damage. Female Wistar rats were subjected to protein restriction during pregnancy and lactation (control group: 25% soybean protein; malnourished group: 7%). Seven days after delivery (PND7), their offspring were submitted to unilateral cerebral HI; rats were then tested for sensorimotor (PND7 and PND60) and memory (PND60) functions. Offspring of malnourished mothers showed marked reduction in body weight starting in lactation and persisting during the entire period of observation. There was a greater sensorimotor deficit after HI in malnourished (M) animals, in righting reflex and in home bedding task, indicating an interaction between diet and hypoxia-ischemia. At PND60, HI rats showed impaired performance when compared to controls in training and test sessions of rota-rod task, however there was no effect of malnutrition per se. In the open field, nourished HI (HI-N) presented an increase in crossings number; this effect was not present in HI-M group. Surprisingly, HI-M rats presented a better performance in inhibitory avoidance task and a smaller hemispheric brain damage as compared to HI-N animals. Our data points to a possible metabolic adaptation in hypoxic-ischemic animals receiving protein malnutrition during pregnancy and lactation; apparently we observed a neuroprotective effect of diet, possibly decreasing the brain energy demand, under a hypoxic-ischemic situation.

Effects of prenatal protein malnutrition on the electrical cerebral activity during development

Early protein restriction during the prenatal period has significant repercussions on the ontogeny and development of the central nervous system. The present study investigates whether early prenatal protein malnutrition could alter the electrical cerebral activity of the progeny. We used Sprague-Dawley female rats of 200 g randomly divided into three groups: a control group that received a diet with 25% of the protein content (lactalbumin), the experimental group, that received a diet with 6% of the protein content and the rehabilitated group that initially received a diet with 6% of the protein content, then switched to a diet with 25% of the protein content after the weaning period (P20D) up to 60 days of life (P60D). Reduction of the protein content from 25% to 6% of lactalbumin in the diet of pregnant rats produces impairment in the electrical cerebral activity in the progeny at P20D and at P60D. The power spectral analysis for each one of the electroencephalograms revealed that prenatal protein malnutrition in rats produced a significant reduction of the alpha (8-13 Hz) and the beta bands (13-30 Hz) and a significant increase of the theta (4-8 Hz), and delta bands (1-4 Hz), at two different stages of life (P20D and P60D). Similar results were obtained for the rehabilitated group. These results indicate that early malnutrition in life affects the ontogeny of the electrical cerebral activity. This insult probably disrupts the establishment of cortical neural circuits during the critical period of brain development. The rehabilitation period did not revert the impairment in the electrical cerebral activity produced by malnutrition. We used one-way ANOVA analysis, followed by Tukey test (*p<0.001).

Diphenyl diselenide-induced seizures in rat pups: possible interaction with GABAergic system

OBJECTIVES

The involvement of the GABAergic system in seizures induced by diphenyl diselenide (PhSe)₂ in rat pups was investigated.

METHODS

To this end, the effect of aminooxyacetic acid hemihydrochloride (AOAA, 20 mg/kg; by intraperitoneal route, i.p.), a GABA-T inhibitor; DL-2,4-diamino-n-butyric acid hydrochloride (DABA, 16 mg/kg; i.p.), an inhibitor of GABA uptake; and γ-aminobutyric acid (GABA, 10 and 40 mg/kg; i.p.), diazepam (3 mg/kg; i.p.) and phenobarbital (40 mg/kg; i.p.), GABAergic agonists as well as picrotoxin (1 mg/kg; i.p.), a GABAA receptor antagonist on (PhSe)₂ (50 and 500 mg/kg, by oral route, p.o.)-induced seizures, were studied. The [(3)H]GABA uptake levels by cortical and hippocampal slices in rat pups exposed to (PhSe)₂ were also carried out.

RESULTS

Pre-treatment with GABA (40 mg/kg), diazepam, phenobarbital, AOAA and DABA abolished the appearance of seizures induced by 50 mg/kg (PhSe)₂ in rat pups. Picrotoxin increased the percentage of convulsing rat pups from 42 to 100% and reduced significantly the onset for the first convulsive episode induced by (PhSe)₂ at the dose of 50 mg/kg. Diazepam and phenobarbital prolonged significantly the latency for the onset of the first convulsive episode caused by 500 mg/kg (PhSe)₂ in rat pups. [(3)H]GABA uptake levels were stimulated in cerebral cortical and hippocampal slices of convulsing rat pups administered with both doses of (PhSe)₂.

DISCUSSION

Our findings demonstrated that seizures induced by (PhSe)₂ are mediated, at least in part, by an interaction with GABAergic system.

Desnutrição, maturação do sistema nervoso central e doenças neuropsiquiátricas

A nutrição exerce profundo impacto no desenvolvimento das estruturas e funções cerebrais. Além da programação metabólica induzida pela desnutrição fetal com o propósito de aumentar as chances de sobrevivência do feto e na vida pós-natal, estudos apontam a deficiência nutricional pré-natal como fator de risco para o desenvolvimento de doenças neuropsiquiátricas. Este artigo propõe-se a considerar aspectos da desnutrição relacionados ao desenvolvimento cerebral, à extensão temporal e funcional do impacto que a mesma acarreta, assim como estabelecer correlações com doenças neuropsiquiátricas, considerando artigos disponíveis na base de dados Medline de 1962 a 2005. Fatos derivados da desnutrição precoce apontam, em sua maioria, caráter permanente em algum grau, se não imediato, prospectivo e comprometedor da performance bioquímica, fisiológica e comportamental. Apesar dos denominados atrasos no desenvolvimento de parâmetros neurológicos, estes não constituem apenas erros funcionais isolados, uma vez que as inter-relações e conexões ideais são influenciadas, ampliando os erros temporais de ocorrência de eventos. A impressão da marca da desnutrição no código genético, ao aumentar os horizontes dos efeitos da desnutrição em uma perspectiva multigeneracional, amplifica os seus efeitos. Aspectos caracterizados como mecanismos compensatórios se, por um lado, apontam para uma habilidade em se adaptar ao estresse, por outro poderiam ser comprometidos na contingência de estresse adicional de ordem ambiental ou emocional. Considerações a respeito dos efeitos subliminares ou expressivos das doenças neuropsiquiátricas sobre a qualidade de vida consolidam a importância do desenvolvimento de pesquisas que se dirijam à compreensão dos impactos e mecanismos que modulam os efeitos da desnutrição sobre o neurodesenvolvimento.

Brain glutathione content and glutamate uptake are reduced in rats exposed to pre- and postnatal protein malnutrition

The brain is particularly susceptible to oxidative insults and its antioxidant defense is dependent on its glutathione content. Protein malnutrition (PMN) is an important and very common insult during development and compromises antioxidant defenses in the body, particularly glutathione levels. We investigated whether brain glutathione content and related metabolic pathways, predominantly regulated by astrocytes (particularly glutamate uptake and glutamine synthesis), are altered by pre- and postnatal PMN in rats. Thus, we measured the glutathione content, glutamine synthetase (GS) activity, and glutamate uptake activity in the cerebral cortex (Cx) and hippocampus of rats subjected to pre- and postnatal PMN and in nourished controls. Although malnourished rats exhibited an ontogenetic profile of glutathione levels in both brain regions similar to that of controls, they had lower levels on postnatal d 2 (P2); in Cx this decrease persisted until postnatal d 15. In addition, we found other changes, such as reduced total antioxidant reactivity and glutathione peroxidase activity on P2, and these were not accompanied by alterations in free radical levels or lipoperoxidation in either brain region. Moreover, malnourished rats had elevated GS and reduced glutamate uptake. Taken together, these alterations indicate specific changes in astrocyte metabolism, possibly responsible for the higher vulnerability to excitotoxic/oxidative damage in malnourished rats. The lower antioxidant defense appears to be the main alteration that causes oxidative imbalance, rather than an increase in reactive oxygen species. Moreover, a recovery of altered metabolic variables may occur during adulthood, despite persistent PMN.