The impact of the COVID-19 pandemic on the mental health of healthcare workers: study protocol for the COVID-19 HEalth caRe wOrkErS (HEROES) study

BACKGROUND

Preliminary country-specific reports suggest that the COVID-19 pandemic has a negative impact on the mental health of the healthcare workforce. In this paper, we summarize the protocol of the COVID-19 HEalth caRe wOrkErS (HEROES) study, an ongoing, global initiative, aimed to describe and track longitudinal trajectories of mental health symptoms and disorders among health care workers at different phases of the pandemic across a wide range of countries in Latin America, Europe, Africa, Middle-East, and Asia.

METHODS

Participants from various settings, including primary care clinics, hospitals, nursing homes, and mental health facilities, are being enrolled. In 26 countries, we are using a similar study design with harmonized measures to capture data on COVID-19 related exposures and variables of interest during two years of follow-up. Exposures include potential stressors related to working in healthcare during the COVID-19 pandemic, as well as sociodemographic and clinical factors. Primary outcomes of interest include mental health variables such as psychological distress, depressive symptoms, and posttraumatic stress disorders. Other domains of interest include potentially mediating or moderating influences such as workplace conditions, trust in the government, and the country's income level.

RESULTS

As of August 2021, ~ 34,000 health workers have been recruited. A general characterization of the recruited samples by sociodemographic and workplace variables is presented. Most participating countries have identified several health facilities where they can identify denominators and attain acceptable response rates. Of the 26 countries, 22 are collecting data and 2 plan to start shortly.

CONCLUSIONS

This is one of the most extensive global studies on the mental health of healthcare workers during the COVID-19 pandemic, including a variety of countries with diverse economic realities and different levels of severity of pandemic and management. Moreover, unlike most previous studies, we included workers (clinical and non-clinical staff) in a wide range of settings.

Qualitative study of the implementation of the Continuity of Care and Rehabilitation Program for people with severe mental disorders in Peru

Objective.

Describe the implementation of the Continuity of Care and Rehabilitation Program (PCC-R) in community mental health centers (CSMCs, Spanish acronym) in Peru.

Methods.

Qualitative study of the implementation of the PCC-R in four CSMCs in Lima and La Libertad, Peru. Forty-two individual semi-structured interviews were conducted, as well as a focus group with five participants, for a total of 47 informants, including users, family members, and professionals involved in the design, implementation, and monitoring of the program.

Results.

The PCC-R is a key program for community mental health services in Peru and it enjoys broad acceptability. Providers and users report satisfaction with its results; however, the program lacks a policy document specifying its objectives, organization, and activities. This would explain the variability in its implementation. The PCC-R has limitations in terms of management of financial and human resources, and it is necessary to improve training and supervision. There is consensus on the need, usefulness, and viability of developing a system to monitor the PCC-R. Good practices and suggestions are presented with a view to addressing these challenges.

Conclusions.

The PCC-R is a flagship program for the CSMCs and for mental health reform in Peru. It has achieved broad acceptability among providers and users. Its implementation combines successes and difficulties, with pending tasks that include developing a policy document, improving resource management, strengthening training and supervision, and implementing a monitoring system for continuous improvement of the program.

[Qualitative study of the implementation of the Continuity of Care and Rehabilitation Program for people with severe mental disorders in PeruEstudo qualitativo sobre a implementação do Programa de Continuidade de Cuidados e Rehabilitação para pessoas com transtornos mentais graves no Peru]

Objetivo.

Describir la implementación del Programa de continuidad de cuidados y rehabilitación (PCC-R) en centros de salud mental comunitaria (CSMC) del Perú.

Métodos.

Estudio cualitativo sobre la implementación del PCC-R en cuatro CSMC de Lima y La Libertad, Perú. Se realizaron 42 entrevistas semiestructuradas individuales y un grupo focal con cinco participantes, para un total de 47 informantes entre usuarios, familiares y profesionales vinculados al diseño, la implementación y el monitoreo del PCC-R.

Resultados.

El PCC-R es un programa central de los servicios de salud mental comunitaria en Perú, goza de amplia aceptación y los prestadores y usuarios refieren estar satisfechos con sus resultados. Sin embargo, el programa carece de un documento normativo que detalle sus objetivos, organización y actividades, lo que explicaría la variabilidad en su aplicación. Existen limitaciones en la gestión de recursos financieros y humanos del PCC-R y necesidades de capacitación y supervisión, que deben ser mejoradas. Existe consenso sobre la necesidad, la utilidad y la viabilidad de desarrollar un sistema de monitoreo del PCC-R. Se recogen buenas prácticas y sugerencias para enfrentar estos retos.

Conclusiones.

El PCC-R es un programa insignia de los CSMC y de la reforma de la salud mental en Perú, y ha logrado amplia aceptación entre los prestadores y usuarios. Su implementación combina aciertos y dificultades, y revela tareas pendientes como desarrollar un documento normativo, mejorar la gestión de recursos, fortalecer la capacitación y acompañamiento, y aplicar un sistema de monitoreo para favorecer la mejora continua del programa.

Signaling pathways involved in neuron-astrocyte adhesion and migration

Astrocytes in the normal brain possess a stellate shape reflecting their non-migratory properties. Alternatively, in neurodegenerative diseases or after injury, astrocytes become "reactive" in a process known as astrocytosis or reactive gliosis, retract their processes, become polarized and acquire front-to-rear asymmetry typical of migratory cells. On the other hand, neuronal migration is a common process during embryonic development, but only few types of neurons can migrate and differentiate during adult life in the central nervous system. Those that do migrate follow tracks made by glial cells and mainly give rise to interneurons. In vitro, molecular mechanisms involved in adhesion of cells to and migration on extracellular matrix proteins have been widely studied; however, signal transduction pathways explaining how particularly neurons and astrocytes, mutually modulate adhesion and migration are less well known. In this review, we describe and discuss how ligand/receptor interactions in astrocytes and neurons trigger signaling events leading to actin and microtubule reorganization, changes in cell morphology, as well as cell adhesion and migration. The biological significance these cell-cell interactions and signaling events might have in the brain are discussed.

Enhancing a declarative memory in humans: the effect of clonazepam on reconsolidation

A consolidated memory recalled by a specific reminder can become unstable (labile) and susceptible to facilitation or impairment for a discrete period of time. This labilization phase is followed by a process of stabilization called reconsolidation. The phenomenon has been shown in diverse types of memory, and different pharmacological agents have been used to disclose its presence. Several studies have revealed the relevance of the GABAergic system to this process. Consequently, our hypothesis is that the system is involved in the reconsolidation of declarative memory in humans. Thus, using our verbal learning task, we analyzed the effect of benzodiazepines on the re-stabilization of the declarative memory. On Day 1, volunteers learned an association between five cue- response-syllables. On Day 2, the verbal memory was labilized by a reminder presentation, and then a placebo capsule or 0.25 mg or 0.03 mg of clonazepam was administered to the subjects. The verbal memory was evaluated on Day 3. The volunteers who had received the 0.25 mg clonazepam along with the specific reminder on Day 2, exhibited memory improvement. In contrast, there was no effect when the drug was given without retrieval, when the memory was simply retrieved instead of being reactivated or when short-term memory testing was performed 4 h after reactivation. We discuss the GABAergic role in reconsolidation, which shows a collateral effect on other memories when the treatment is aimed at treating anxiety disorders. Further studies might elucidate the role of GABA in the reconsolidation process associated with dissimilar scenarios. This article is part of a Special Issue entitled 'Cognitive Enhancers'.

Absence of tissue factor expression by neoplastic plasma cells in multiple myeloma

Thrombosis portends a poor prognosis in individuals with solid tumors. Constitutive expression of tissue factor (TF) by cancer cells is a key in triggering activation of coagulation and promoting aggressive tumor behavior. Though multiple myeloma (MM) is associated with a high frequency of thrombosis in the context of thalidomide and lenalidomide therapy, prognosis is not affected by its occurrence. We sought to determine the expression of TF in MM. F3 (TF gene) expression profiling was analyzed in 55 human MM cell lines (HMCL) and in 223 solid tumor cell lines obtained from GlaxoSmithKline (GSK) Cancer Cell Line Genomic Profiling Dataset. TF was not expressed in any of the 55 HMCLs studied, in sharp contrast to solid tumors, 90% of which showed TF expression. F3 expression was also absent in tumor samples from 239 MM patients. Immunohistochemistry for TF was negative, with either no or focal (1+) staining in 70/73 MM patients. Only three marrow biopsies were moderately (2+) positive either focally or diffusely, suggesting that in rare cases bone marrow microenvironment may support TF expression. General lack of TF expression by neoplastic plasma cells may explain why thrombosis is not predictive of poor outcome, and why aspirin prophylaxis is often effective in MM.

Latitudinal prevalence gradient of multiple sclerosis in Latin America

BACKGROUND

Multiple sclerosis (MS) has a unique geographical distribution that reflects both genetic and environmental factors. Many studies have shown a positive correlation between MS frequency and latitude across both large and small geographical regions. However, scarce data have been published on the epidemiology of MS in Latin America and no study has evaluated latitudinal variation.

OBJECTIVE

To evaluate the effect of latitude on MS prevalence in Latin America.

METHODS

We conducted a systematic review of MS prevalence during January 2011. Prevalence rates were collected from eligible publications. The effect of latitude on prevalence was analyzed using linear regression.

RESULTS

A total of ten studies were eligible for analysis, corresponding to six countries, spanning from Panama to Argentina. The crude prevalence of MS ranged from 0.75 to 21.5 per 100,000. We found a strong and significant association between prevalence and latitude (r(2) 0.8; p < 0.001) and determined an increase in prevalence of 0.33 per 100,000 per degree latitude.

CONCLUSION

Our findings suggest a latitudinal prevalence gradient of MS in Latin American countries between Panama and Argentina.

Midazolam disrupts fear memory reconsolidation

The current research examines the influence of midazolam (MDZ) on memory reconsolidation using a contextual fear paradigm in rats, based on three context-shock training trials (0.7 mA, 3 s). First, we evaluate the effect of MDZ (1 mg/kg, i.p.) injected shortly after the training procedure. Second, we examined the influence of MDZ after a brief exposure (90 s) either in the training context (reactivation procedure) or in a neutral environment (no reactivation procedure) and one day later, freezing behavior was scored when rats were re-exposed to the training environment. Third, we investigate both the effect of MDZ administered at different times following reactivation on fear memory and the persistence of such effect 10 days after reactivation. Finally, we test whether the MDZ effect could be reverted by a single weak training trial (0.2 mA, 3 s) or by the presentation of the same unconditioned stimulus in the absence of the conditioned stimulus as a reminder which proves to induce significant freezing in rats not previously trained. Results show that MDZ interferes with the formation of a contextual fear memory only when administered after the reactivation procedure but not after the training procedure. This interference was effective up to 60 min after reactivation and not at a later time. No spontaneous recovery of freezing behavior was observed 11 days after MDZ injection which was not reverted by a weak training trial and by the unconditioned stimulus alone. All these data support the idea that stimulating GABA A receptor sites via MDZ selectively disrupts the reconsolidation process of a contextual fear memory.

Polymorphisms in the TNFA gene promoter region show evidence of strong linkage disequilibrium with HLA and are associated with delayed neutrophil engraftment in unrelated donor hematopoietic stem cell transplantation

Sustained myeloid engraftment is an important determinant of outcome in hematopoietic stem cell transplantation (HSCT). Human tumor necrosis factor (TNF)-alpha is encoded by a gene, TNFA, located in the class III region of the major histocompatibility complex on chromosome 6, flanked by the human leukocyte antigen (HLA) class I and II regions. A number of polymorphisms in the promoter region of the TNFA gene have been associated with increased production of TNF-alphain vivo. Additionally, raised TNF-alpha levels have been reported to have a detrimental effect on the outcome in HSCT, in particular on early complications such as acute graft vs host disease, failure to engraft, and transplant-related mortality. There is evidence of linkage disequilibrium (LD) between TNFA promoter polymorphisms and extended HLA haplotypes. We have genotyped 73 cell lines and 189 donor/recipient pairs (undergoing HSCT) for their TNFA polymorphism, all of which had been well characterized with respect to their HLA genes. We found evidence of strong LD between HLA genes and TNFA; however, there was also evidence for recombination events having taken place, as we found that a number of transplant pairs who were matched for their HLA haplotypes were not matched for their TNFA alleles. We analyzed early outcomes in the transplant recipients and found a significant delay in engraftment in those pairs where both donor and recipients possessed an AG allele (associated with higher TNF-alpha levels). Our results suggest a functional effect of TNFA polymorphisms on myeloid engraftment in unrelated HSCT.

Angiotensin II and the transcription factor Rel/NF-kappaB link environmental water shortage with memory improvement

One of the essential requirements even in the most ancient life forms is to be able to preserve body fluid medium. In line with such requirement, animals need to perform different behaviors to cope with water shortages. As angiotensin II (ANGII) is involved on a widespread range of functions in vertebrates, including memory modulation, an integrative role, in response to an environmental water shortage, has been envisioned. Previous work on the semi-terrestrial and brackish-water crab Chasmagnathus granulatus showed that endogenous ANGII enhanced an associative long-term memory and, in addition, that high salinity environment induces both an increase of brain ANGII levels and memory improvement. Here, we show that in the crab Chasmagnathus air exposure transiently increases blood sodium concentration, significantly increases brain ANGII immunoreactivity, and has a facilitatory effect on memory that is abolished by a non-selective ANGII receptor antagonist, saralasin. Furthermore, Rel/NF-kappaB, a transcription factor activated by ANGII in mammals and during memory consolidation in Chasmagnathus brain, is induced in the crab's brain by air exposure. Moreover, nuclear brain NF-kappaB is activated by ANGII, and this effect is reversed by saralasin. Our results constitute the first demonstration in an invertebrate that cognitive functions are modulated by an environmental stimulus through a neuropeptide and give evolutionary support to the role of angiotensins in memory processes. Moreover, these results suggest that angiotensinergic system is preserved across evolution not only in its structure and molecular mechanisms, but also in its capability of coordinating specific adaptative responses.

(+)-epi-Alpha-bisabolol [correction of bisbolol] is the wound-healing principle of Peperomia galioides: investigation of the in vivo wound-healing activity of related terpenoids

Bioassay-guided investigation of the ethanol extract of Peperomia galioides using a tensile strength method in mice as a monitor led to the isolation of epi-alpha-bisabolol (1) (ED(50) 155 microg/mL). An in vivo healing study of selected commercially available monoterpenoids yielded two bioactive compounds, alpha-bisabolol (2) and alpha-terpineol (3) (ED(50) of 228 and 240 microg/g mouse[corrected], respectively).

Characterisation of cAMP-dependent protein kinase isoforms in the brain of the crab Chasmagnathus

In the crab Chasmagnathus learning model, systemic administration of cAMP analogues that are specific activators or inhibitors of cAMP-dependent protein kinase (PKA) proved to respectively facilitate or impair long-term retention. The aims of the present work were to analyse PKA activity distribution in the crab brain and to characterise PKA isoforms. The neuropils from the eyestalk showed higher levels of induced PKA activity when compared with other neuropils of the central nervous system. Two PKA isoforms, homologous to mammalian PKA I and PKA II, were detected from central brain protein extracts using DEAE chromatography. Only PKA II was found in lateral protocerebrum extracts, suggesting a role of this isoform in the processing of visual inputs and in the integration of this information with other sensory inputs. PKA I was observed to be ten-fold more sensitive to cAMP than PKA II. cGMP induced a high activation of both PKA isoforms, similar to that obtained with cAMP. PKA I showed a two-fold greater sensitivity for cGMP than PKA II. An autophosphorylation assay was performed and a protein of 55 kDa, corresponding to phosphorylated R II regulatory subunit, was detected. The presence of a PKA I isoform with high sensitivity for cAMP in the central brain suggests a role of this subtype in long-term memory.

High environmental salinity induces memory enhancement and increases levels of brain angiotensin-like peptides in the crab Chasmagnathus granulatus

Previous work on the brackish-water crab Chasmagnathus granulatus demonstrated that an endogenous peptide similar to angiotensin II plays a significant role in enhancing long-term memory that involves an association between context and an iterative danger stimulus (context-signal memory). The present results show that this memory enhancement could be produced by moving crabs from brackish water to sea water (33.0%) and keeping them there for at least 4 days. The possibility that such a facilitatory effect is due to osmotic stress is ruled out. Coincidentally, the level of angiotensin-II-like peptides in crab brain, measured by radioimmunoassay, increases with the length of exposure to sea water, reaching a significantly different level at the fourth day. The presence of angiotensin-II-like immunoreactive material in neural structures of the supraoesophageal and eyestalk ganglia was confirmed by immunohistochemical analysis. The results are interpreted as supporting the hypothesis that exposure to water of high salinity is an external cue triggering a process mediated by angiotensins that leads to enhanced memory in these crabs.

Long-lasting and context-specific freezing preference is acquired after spaced repeated presentations of a danger stimulus in the crab Chasmagnathus

A visual danger stimulus elicits an escape response in the crab Chasmagnathus that declines after repeated presentations. Previous results report that such waning may be retained as context-signal memory (CSM) or signal memory (SM): CSM is long lasting, associative, and produced by spaced training, while SM is an intermediate memory, nonassociative, and produced by massed training. The performances of both spaced and massed trained crabs are here examined, using video analysis to determine topographic changes in the behavioral response during and after training. During spaced training, escape vanishes and is mainly replaced by freezing, while during massed training, escape decreases over trials without being replaced by any defensive response. After 24 h, the marked proclivity to freezing persists in spaced trained crabs, while a high level of escaping is shown by massed trained crabs. The long-lasting freezing preference of spaced trained crabs proves to be context-specific and apparent from the very first presentation of the danger stimulus at testing, though freezing is not triggered by the sole exposure to the context. We conclude (a) that freezing preference is the acquired response of the CSM process; (b) that CSM can be properly categorized as an instance of contextual conditioning and SM of classical habituation; (c) that CSM and SM are not two phases of a memory processing but two distinctly types of memory; and (d) that therefore, the temporal distribution of training trials has a drastic effect on crab's memory, more dramatic than that previously described. The possibility that massed and spaced presentations of the same stimulus may represent two different stimulus types is discussed.

Prevalence of gastroesophageal reflux disease in patients with extraesophageal symptoms referred from otolaryngology, allergy, and cardiology practices: a prospective study

AIM

To investigate the prevalence of gastroesophageal reflux disease (GERD) as well as the clinical, endoscopic, and manometric characteristics in 57 adult patients with otolaryngeal symptoms, asthma, or noncardiac chest pain referred from specialized services.

METHODS

The following evaluations were performed: (1) upper endoscopy, (2) 24-hour ambulatory esophageal pH monitoring, and (3) esophageal manometry. The prevalence of GERD was determined, and demographic, clinical, endoscopic, and manometric characteristics of patients with or without GERD were evaluated.

RESULTS

Thirty-four out of 57 patients (60%) had GERD. The 95% confidence interval ranged from 48 to 72%. There was no statistical difference between patients with or without GERD regarding gender, age, or time of evolution of symptoms. Cough was more frequent in the subjects with GERD (75 vs. 25%, p<0.05). Nevertheless, cough was observed in only 53% of the patients with GERD. Patients suffering from laryngitis had a greater proximal and distal esophageal acid exposure time than those without.

CONCLUSIONS

The prevalence of GERD was 60%. There is not a definite demographic or clinical profile that permits us to distinguish between patients with and without GERD among those with ear, nose, and throat and pulmonary symptoms or chest pain.

Two related forms of long-term habituation in the crab Chasmagnathus are differentially affected by scopolamine

An opaque screen moving overhead elicits an escape response in the crab Chasmagnathus, which, after a few presentations, habituates for a long period (long-term habituation, LTH). Previous results distinguished two types of LTH: the (context-signal)-LTH yielded by spaced training, determined by an association between context and habituating stimulus, and cycloheximide sensitive: and the (signal)-LTH produced by massed training, context independent, and cycloheximide insensitive. Present experiments were aimed at studying the possible involvement of cholinergic mechanisms in one or both types of LTH, using the muscarinic antagonist, scopolamine (SCP). Results indicate that LTH acquired by spaced training (30 trials separated by 85 s) is blocked in a dose-dependent manner by posttraining SCP. Amnesia is shown with 100 ng SCP/g injected immediately before or after spaced training but not delayed 1-h posttraining. No effect of SCP on LTH acquired by massed training (300 trials separated by 4 s) is detected. Pretraining SCP induces a decrease in the response level at the initial trials of either a spaced or a massed training. It is concluded that the storage of (context-signal)-LTH may be selectively regulated by a muscarinic-cholinergic mechanism. However, the possibility that other cholinergic receptors would be involved in the consolidation of the (signal)-LTH is discussed.

Memory enhancement by the angiotensinergic system in the crab Chasmagnathus is mediated by endogenous angiotensin II

In previous work with the crab Chasmagnathus, it was reported that either exogenous angiotensin II (ANGII) or angiotensin IV (ANGIV), have an enhancing effect on long-term memory, which involves an association between context and an iterative danger stimulus (context-signal memory, CSM). Present results indicate that Dival, an ANGIV antagonist, reverts the facilitatory effect of ANGIV but not that of ANGII, whereas saralasin but not Dival, disrupts CSM. These findings suggest that ANGII is the endogenous angiotensin that plays a significant role in long-term memory, while the ANGIV receptor would not be encompassed in the cascade of events related to crab's CSM.

Context shift and protein synthesis inhibition disrupt long-term habituation after spaced, but not massed, training in the crab Chasmagnathus

An opaque screen moving overhead elicits an escape response in the crab Chasmagnathus that after a few presentations habituates for a long period (long-term habituation, LTH). Previous results suggested that spaced (15 trials separated by 171 s) and massed training (300 trials without rest interval) were correlated with two different memory components of LTH. The present experiments were aimed at further studying the mechanisms subserving these components. Results indicate that LTH acquired by spaced but not by massed training is blocked either by a training-to-testing context shift or by cycloheximide (15-25 microg) pre- or posttraining injection and that LTH after spaced training persists for longer time (5 days) than after massed training (2 days). A model based on these results that distinguishes two LTH-memory components is proposed: a (context-signal) LTH yielded by spaced training, dependent of context, sensitive to cycloheximide (CYX), and long lasting; and a (signal) LTH yielded by massed training, dependent only on the signal invariance, insensitive to CYX, and shorter lasting.

Kappa-B like DNA-binding activity is enhanced after spaced training that induces long-term memory in the crab Chasmagnathus

Regulation of gene expression has been involved in long-term memory consolidation. Present results support the role of Rel/ NFkappa-B like activation in this process. In the crab Chasmagnathus, the spaced presentation of 15 or more danger stimuli induces long-term habituation (LTH), while no LTH is observed after a massed training of 600 trials. When a group trained with 30 spaced trials was compared with a passive control group and massed trained groups, a higher level of specific Rel/kappa-B like DNA-binding activity was found in brain nuclear extracts. These results strongly suggest that the enhancement of Rel/kappa-B like DNA-binding activity in the brain is specifically related to LTH formation.

Caveolae a new subcellular transport organelle

Recent advances have allowed the identification and characterization of well defined vesicular subcellular organelles involved in multiple basic cellular physiological processes, with demonstrated clinical relevance. Among these, three particular subcellular organelles have received special attention based on their proven and postulated participation in the sorting and targeting of small-and large-molecular weight molecules during exocytosis and endocytosis, and in cell signaling and transduction events. These have characteristic proteinaceous coat structures that allows their classification accordingly, into what has been described as clathrin coated vesicles and COP-coated vesicles and caveolae. In this review article a brief description of clathrin-coated vesicles and COP-coated vesicles is presented. Caveolae (CAV), in turn, constitute a novel subcellular organelle that has received special attention based on its proven and postulated participation in transcytosis, potocytosis, and in cell signaling and transduction events. In this review of the literature a more extensive discussion is presented of CAV. In this context the article discusses the structural features of caveolae, its constituent protein caveolin(s), the functional aspects of this new organelle, and its postulated clinical relevance.

Long-term habituation (LTH) in the crab Chasmagnathus: a model for behavioral and mechanistic studies of memory

A decade of studies on long-term habituation (LTH) in the crab Chasmagnathus is reviewed. Upon sudden presentation of a passing object overhead, the crab reacts with an escape response that habituates promptly and for at least five days. LTH proved to be an instance of associative memory and showed context, stimulus frequency and circadian phase specificity. A strong training protocol (STP) (> or = 15 trials, intertrial interval (ITI) of 171 s) invariably yielded LTH, while a weak training protocol (WTP) (< or = 10 trials, ITI = 171 s) invariably failed. STP was used with a presumably amnestic agent and WTP with a presumably hypermnestic agent. Remarkably, systemic administration of low doses was effective, which is likely to be due to the lack of an endothelial blood-brain barrier. LTH was blocked by inhibitors of protein and RNA synthesis, enhanced by protein kinase A (PKA) activators and reduced by PKA inhibitors, facilitated by angiotensin II and IV and disrupted by saralasin. The presence of angiotensins and related compounds in the crab brain was demonstrated. Diverse results suggest that LTH includes two components: an initial memory produced by spaced training and mainly expressed at an initial phase of testing, and a retraining memory produced by massed training and expressed at a later phase of testing (retraining). The initial memory would be associative, context specific and sensitive to cycloheximide, while the retraining memory would be nonassociative, context independent and insensitive to cycloheximide.

Angiotensin II (3-8) induces long-term memory improvement in the crab Chasmagnathus

A shadow moving overhead acts as a danger stimulus and elicits an escape response in the crab Chasmagnathus that habituates after 15 trials and for a long period of time. Previous work showed that angiotensin II enhances this long-term memory. Present results indicate: (1) that the facilitatory effect of angiotensin II is not blocked by either losartan, DUP 753 or the Parke Davis compound PD 123177; (2) that the angiotensin II (3-8) fragment has an enhancing effect on crab's memory stronger than that reported for the integer octopeptide; (3) that the hypermnestic effect of angiotensin II (3-8) is dose-dependent and saralasin reversible. The possibility that the action of angiotensin II on crab's memory were not due to its own action but to that of the degradation fragment angiotensin II (3-8) is discussed.

Evaluation of the wound-healing activity of selected traditional medicinal plants from Perú

Folk medicine practitioners in Perú employ plant preparations as wound-healing agents on superficial and internal wounds (gastric ulcers). The results of a scientific evaluation of the wound-healing activity of nine plants found in the Amazon jungle near Iquitos and in the Andes mountains is presented. The species studied were: Peperomia galioides, Mentzelia cordifolia, Mutisia acuminata, Himatanthus sucuuba, Spondias mombin, Eleutherine bulbosa, Muehlenbeckia tamnifolia, Anredera diffusa and Jatropha curcas. These plants have also been examined for their toxicological properties, their effect on blood pressure, smooth muscle and capillary permeability. Significant wound-healing activity was detected in Peperomia galioides, Anredera diffusa and Jatropha curcas. Extracts from Peperomia galioides and Anredera diffusa had no effect on cell proliferation and did not exhibit mutagenic activity.

Effects of activation and inhibition of cAMP-dependent protein kinase on long-term habituation in the crab Chasmagnathus

On sudden presentation of a danger stimulus, the crab Chasmagnathus elicits an escape response that habituates promptly and for a long period. We have previously reported that administration of a cAMP-permeable analog (CPT-cAMP) along with a phosphodiesterase inhibitor (IBMX) improves long-term habituation (LTH). In present experiments we studied the effect of systemic administration of the protein kinase A (PKA) activator Sp-5,6-DCl-cBIMPS and that of the PKA inhibitor Rp-8-Cl-cAMPS on LTH tested 24 h after a weak training protocol (5 trials of danger stimulus presentation) or a strong training protocol (15-30 trials), respectively. A 50 microliters pre-training injection of 75 microM Sp-5,6-DCl-cBIMPS, and to a lesser degree of 25 microM, improved retention of the habituated response but not affect short-term habituation (STH). Like pre-training injection, post-training administration of Sp-5,6-DCl-cBIMPS proved to exert a facilitatory action on retention though with 75 microM dose only. Conversely, both pre- and post-training injection of 25 microM Rp-8-Cl-cAMPS impaired LTH without affecting STH. Thus, the PKA activator Sp-5,6-DCl-cBIMPS enables a weak training to produce LTH while the PKA inhibitor Rp-8-Cl-cAMPS impairs LTH when a strong training is given. Activation of crab PKA by Sp-5,6-DCl-cBIMPS and its inhibition by Rp-8-Cl-cAMPS were assessed using an in vitro PKA activity assay. These results provide independent evidences supporting the view that PKA plays a key role in long-term memory storage in this learning paradigm.

Inhibitors of protein and RNA synthesis block context memory and long-term habituation in the crab Chasmagnathus

The crab Chasmagnathus granulatus reacts to a shadow passing overhead (a danger stimulus) with an escape response that habituates quickly and for at least 5 days. Recently, it has been reported that cycloheximide (CY) disrupts this long-term habituation and the corresponding context memory. In the present article, experiments with CY and an inhibitor of RNA synthesis, actinomycin-D (ACT), were parallelly conducted. An injection of CY (20 micrograms) or ACT (0.62 microgram) reduced the incorporation of [14C]-aminoacid into cerebral plus thoracic ganglia by 80% for 2 h and 59.7% for 1 h, respectively, but no inhibition was found at 24 h. Both ACT (0.62 microgram) and CY (20 micrograms) administered immediately after training (15 trials with the danger stimulus) impaired either long-term habituation or context memory when tested at 24 h. Because ACT and CY have in common only their direct or indirect inhibitory effect on protein synthesis, this finding is considered as an additional evidence that long-term memory in Chasmagnathus requires de novo protein synthesis. However, pretraining ACT or CY impaired context memory at 24 h but not long-term habituation. Such a disparity is explained by an unspecific attenuating effect upon the response, attributed to drug x training interaction. Neither ACT nor CY affected short-term habituation.

Serotonin-induced short- and long-term sensitization in the crab Chasmagnathus

On sudden presentation of a passing shadow (a visual danger stimulus), the crab Chasmagnathus granulatus responds with a running reaction that we term an escape response (ER). A single administration of 5-HT in a dose range between 0.005 and 0.1 microgram/g enhances the ER at 30 min, and a dose of 10-15 micrograms/g has a similar effect for at least 24 h. The classical 5-HT antagonist cyproheptadine (CYP) given within a dose range 0.01-2.0 micrograms/g has no effect on ER at 30 min, but 0.5 microgram/g blocks the 5-HT-induced short-term sensitization. An enhancing effect of CYP on the ER is shown at 24 h with 1.0-2.0 micrograms/g doses. An explanation of this results in terms of a model similar to that proposed for Aplysia, that is two sensitizing processes linked in parallel and mediated by two different types of 5-HT receptors is discussed. Results indicate that the sensitizing effect of 5-HT is confined to high responders, thus suggesting that crabs of a same population have different degrees of sensitivity to the drug according to their different degrees of reactivity to the visual danger stimulus.

Acute administration of a permeant analog of cAMP and a phosphodiesterase inhibitor improve long-term habituation in the crab Chasmagnathus

A shadow passing overhead acts as a danger stimulus and elicits an escape response in the crab Chasmagnathus that habituates promptly and for a long period. Robust retention is shown at 24 h after 15 trials of shadow presentation or at 120 h after 30 trials, but no significant retention is disclosed at 24 h after 5 trials or at 72 h after 15. A cocktail of the cAMP membrane permeable analog 8-(4-chlorophenylthio)-cAMP (CPT-cAMP), plus the phosphodiesterase inhibitor isobutyl methylxanthine (IBMX), was given by systemic administration. Pretraining injection of the cocktail (25 or 50 microM, 15 min before a 5-trial session) failed to affect short-term habituation, but induced significant retention when tested at 24 h. This facilitatory effect was not shown when a lower dose (5 microM) was used. A post-training injection of 25 microM, immediately after a 5- or 15-trial session, induced retention when tested at 24 or 72 h, respectively. Thus, the administration of CPT-cAMP + IBMX during acquisition of a habituated response or immediately after, improves long-term habituation, a result supporting the view that an increase in the cAMP level is one of the steps in long-term memory consolidation.

Training-to-testing intervals different from 24 h impair habituation in the crab Chasmagnathus

A shadow moving overhead elicits an escape response in the crab Chasmagnathus that habituates promptly and for a long period. Experiments were done to test the effects of time of day (light-phase vs. dark-phase) on the acquisition and retention of the habituated response. The short-term habituation produced by the repetitive presentation of the stimulus does not differ between the two phases of the day though their reactivity during training seems to be higher during the dark phase than during the light, in agreement with the peak of circadian locomotor activity. The magnitude of the long-term habituated response, tested 24 or 72 h after training, does not appear to depend either on the time of day of training or on that of testing, but the retention is impaired when testing is conducted at a time of day that differs from that of the original training. Thus, results indicate a) that habituation of a response to a stimulus presented during the dark phase is not generalized to the same stimulus presented during the light phase, and vice versa; and b) that during training not only information regarding the target stimulus is stored but also information about the phase of the day.

Angiotensin II enhances long-term memory in the crab Chasmagnathus

An opaque screen moving overhead provokes an escape response in the crab Chasmagnathus granulatus that habituates after a few presentations of the eliciting stimulus. Fifteen trials with a 180-s intertrial interval or 30 trials with a 90-s interval (strong training protocol) ensures long-term habituation (LTH) of the response for 24 h, whereas 10 trials (weak training protocol) fail to induce it. However, robust LTH is obtained when crabs are injected with human angiotensin (All; 50 pmol) immediately after a weak training protocol. This memory-enhancing effect of All is dose-dependent, reversible by saralasin (5 pmol), and vanishes either when the weak training protocol is reduced to only five trials, or when the peptide is given before training or 1 h after. LTH is impaired by saralasin (5 pmol) administered before or after the strong training protocol, but no amnestic effect is disclosed when the antagonist is given 1 h after. On the other hand, both All-like immunoreactivity and angiotensin-converting enzyme-like activity are described in diverse tissues of Chasmagnathus, namely, in gills and in both thoracic and supraesophageal ganglia. Results support the view that some components of the renin-angiotensin system and their influence on memory might have emerged early in evolution.

Cycloheximide inhibits context memory and long-term habituation in the crab Chasmagnathus

A shadow moving over head elicits an escape response in the crab Chasmagnathus that habituates promptly and for a long period. The effect of the protein synthesis inhibitor cycloheximide (CY) on this long-term memory was analyzed. Two hours after injection, 10 micrograms CY inhibited [14C]-amino amino acid incorporation into cerebral plus thoracic ganglia by 88% and 20 micrograms by 92%, but no inhibition was found at 24 h. A single injection of 10-20 micrograms CY given 30 min before training, failed to affect the short-term habituation. Similar doses impaired both context memory (CM) and long-term habituation (LTH) when tested at 72 and 120 h but only CM at 24 h. Such a disparity was explained by an unspecific depressing effect upon the response, attributed to an interaction between CY and training. The hypothesis was confirmed, because CY injected immediately after training disclosed amnestic effect at 24 h on both CM and LTH. A similar effect was proven when animals were injected at 2 h but not at 6 h after training. Results from experiments with pretraining and pretesting injections put aside a state-dependence or retrieval deficit effects of the drug. Taken together, findings of this article argue strongly for de novo protein synthesis as a mechanism of LTH and for the close relation between CM and LTH.

Acute administration of angiotensin II improves long-term habituation in the crab Chasmagnathus

A shadow moving overhead acts as a danger stimulus and elicits an escape response in the crab Chasmagnathus granulatus that habituates after 15 trials and for a long period. A shorter training of ten trials fails to induce long-term habituation; however, a good retention of the habituated response is manifest after a 24-h interval when angiotensin II (AII) (10(-6) M, 3 ng/g) is injected post-training. By contrast, no amnestic effect of AII was found even though high doses were administered. The facilitatory effect of AII is suppressed by saralasin (10(-7) M, 0.3 ng/g), a specific angiotensin II receptor antagonist. Results are considered as suggesting that angiotensin on memory processes might have emerged early in evolution.

Ethanol affects context memory and long-term habituation in the crab Chasmagnathus

A shadow moving overhead acts as a danger stimulus and elicits an escape response in the crab Chasmagnathus granulatus that habituates promptly and for a long period. The effect of acute ethanol treatment on this long-term memory was analyzed. A single injection of 0.01, 0.05, or 0.1 micrograms ethanol (ET)/g given 30 min before iterated presentation of a visual danger stimulus failed to affect short-term habituation. Posttraining ethanol (0.01 to 0.1 microgram/g) produces a dose-dependent impairment of long-term habituation, but pretraining ethanol had no amnestic effect. However, a retention deficit confined to context memory was disclosed with both pre- and posttraining ethanol. Results from experiments with double injection (posttraining and pretesting injections) account for the retention impairment in terms of true amnesia (failure to acquire memory) but not due to state-dependence or retrieval deficit. The nonamnestic effect of pretraining ethanol upon long-term habituation is explained by a nonespecific depressing effect caused by interaction between iterative presentation of the danger stimulus and drug-induced internal state during training.

Modulation of the escape response by [D-Ala2]Met-enkephalin in the crab Chasmagnathus

The synthetic opioid analog [D-Ala2]Met-enkephalin (DAME) significantly reduces the escape response to a danger stimulus in the crab Chasmagnathus granulatus when administered within the dose range 0.01-1.0 micrograms/g. There is no reduction with lower or higher doses, thus suggesting a U-shaped dose-response curve. A 0.1-microgram/g dose of naloxone has no effect per se on the response, but when it is administered together with DAME, it completely blocks the decremental effect of this drug and an escape response generally higher than that of control is observed. An explanation for these results in terms of a possible dual action of DAME is offered. In addition, we present evidence for different degrees of opiate sensitivity among crabs of the same population in relation to their different degrees of reactivity to the visual danger stimulus.

Octreotide therapy of large-volume refractory AIDS-associated diarrhea: a randomized controlled trial

OBJECTIVE

To compare the effect of octreotide (a long-acting somatostatin analog) to that of antidiarrheal therapy plus placebo on large-volume refractory AIDS-associated diarrhea.

DESIGN

A randomized controlled trial.

SETTING

Referral-based clinic and hospital in a tertiary care center.

PATIENTS

Twenty male patients with AIDS and refractory diarrhea, with stool volume > 1000 ml/day who failed to improve after initial supportive management. All patients finished the study.

INTERVENTIONS

Patients were randomly given either octreotide in doses of 100, 200 and 300 micrograms subcutaneously every 8 h, or high doses of loperamide and diphenoxylate orally plus placebo subcutaneously for 10 days.

MAIN OUTCOME MEASURES

Bowel movements and stool volume were registered before and every day after treatment by the patients themselves and the nursing personnel.

RESULTS

Patients from both groups were similar for age, time of AIDS diagnosis, duration of diarrhea and etiology. Baseline mean bowel movements per day (9.4 +/- 2.8 in the octreotide group versus 10 +/- 3.1 in controls) and baseline mean stool volume (2753 +/- 840 versus 2630 +/- 630 ml/day, respectively) were similar in both groups before therapy (P < 0.05). Mean bowel movements per day after 10 days of therapy was 2.1 +/- 1.6 in the octreotide group versus 7 +/- 3 in controls (P < 0.05). Mean stool volume after 10 days of therapy was 485 +/- 480 in the octreotide group versus 1080 +/- 420 ml/day in controls (P < 0.05). Complete response (stool volume < 250 ml/day) was observed in two patients from the octreotide group and none from controls; partial response (decrease > 50% in stool volume) in four and two; and no response (decrease < 50% or no change) in four and eight (P < 0.05), respectively. Side-effects occurred in eight out of 10 octreotide patients and three out of 10 controls (P < 0.05), but none were significant to result in discontinuation of medication.

CONCLUSION

Octreotide proved to be superior to conventional therapy in this short-term treatment of large-volume refractory AIDS-associated diarrhea.

Cell volume and ph regulation by the Amphiuma red blood cell: A model for hypoxia-induced cell injury

The Amphiuma red blood cell is one of the model systems employed early in the study of vertebrate cell volume regulation. Following both cell swelling and shrinkage the Amphiuma red blood cell demonstrates volume regulation to virtual completion in 90-120 min. When swollen the Amphiuma red blood cell loses K, Cl and osmotically obliged water, while following shrinkage volume regulation is the result of Na, Cl and therefore water uptake. The main contribution of the Amphiuma red cell as a model is that it was the first cell in which volume regulation was demonstrated to be electroneutral and more specifically that K/H and Na/H exchangers were responsible for regulation following cell swelling and shrinkage, respectively. Additionally, the Amphiuma red blood cell K/H and Na/H exchangers have been demonstrated to function in a pH regulatory capacity. The latter observation in turn led to the demonstration of the mutually exclusive and contradictory nature of volume and pH regulation predicted upon Na/H exchanger activity. These observations prompted our recent investigations of the Na/H exchanger as a contributor to hypoxia-induced cell damage, using the rabbit heart as a model. These studies illustrated that Na, and Ca imbalances characteristic of hypoxia-induced cell damage are ultimately referable to the Na/H exchanger's function in a pH regulatory capacity, which contributes fundamentally to cell volume and Ca derangement and ultimately cell injury.

Opiate effect on the threat display in the crab Carcinus mediterraneus

The well-known defense response of a crab (laterus merus display, LMD) was easily evoked in Carcinus mediterraneus by striking the cephalothoraxic protogastric region between the eyestalks. Following a program aimed at investigating the regulatory action of diverse neuromodulators on the LMD of this crab, a study on the role of opioids was started by testing the effect of morphine administration. Injection of morphine HC1 (MP) (40, 50, 60, 70, or 100 micrograms/g) produced a dose-dependent reduction of the LMD so elicited that dissipated with the postinjection time. Only MP doses higher than 50 micrograms/g were effective 30 min after drug administration. The MP-induced inhibition of LMD was blocked by a 4.8-micrograms naloxone HC1/g dose injected 10 min before MP. These results and those previously obtained as the action of GABA on the LMD of this crab are discussed in connection with results reporting a similar effect of these drugs on another agonistic item of behavior in the crab Chasmagnatus granulatus. The possibility of demonstrating habituation of the LMD to an iterated stimulation in C. mediterraneus and of using such a process to elucidate the acting paths of the drugs is discussed.

Multitrial inhibitory avoidance learning in the crab Chasmagnathus

Chasmagnathus crabs placed in the dark compartment (DC) of a double-chamber device and given electrical shocks whenever they entered or remained in the light compartment (LC), showed an LC-avoidance behavior when tested 24 h after a training session of three 30-min periods with 60-min intervals. The avoidance behavior depended neither on the shock number nor on the distribution at training but only on exposure to the LC-shock contingency, thus suggesting that crabs learn to associate the LC with an aversive situation. The learning outcome disclosed a higher degree of refraining from entering the LC rather than a faster escaping to the DC. Distributed practice proved more effective on crab avoidance learning than massive practice. Retention of the learned behavior occurred after a 24-h rest interval in an environment different from that of the training apparatus. Experimental devices previously used in avoidance learning studies with crabs were improved here by automating both the computation of latency values and the event recording.

Variations of magnesium, iron, copper and zinc during the colonic wound healing process: experimental study on rabbits

The role of trace elements in the wound-healing process is still controversial. Their variations within a normal colonic wound healing have never been studied. An experimental study on rabbits was designed to study magnesium, iron, copper and zinc variations in blood, normal colonic walls and colonic anastomoses on each of the first 7 postoperative days. No major variations of Mg could be observed. Fe decreased in blood as well as in colonic walls and anastomoses. Cu increased in blood, whereas it decreased in colonic walls and anastomoses. Zn decreased in blood, whereas it increased in colonic walls without significant changes in anastomoses. The role of Fe seemed to be rather difficult to understand. Plasma mobilization seems to explain the local use of Zn, while early tissue release with further return in blood occurred for Cu. The importance of a well-balanced nutritional status is underlined to prevent and correct the variations of trace elements in the postoperative course.

Conditioned facilitatory modulation of the response to an aversive stimulus in the crab Chasmagnathus

A mild electrical shock delivered to the walking legs of the crab Chasmagnathus granulatus through a fine layer of sea water, induces a running response that declines after repeated stimulation. Herein, a first series of experiments was aimed at conditioning the response to a light or a dark pulse, but no detectable CR was disclosed during training nor in a later test with the CS alone, even though several stimulus parameters were assayed. In a second series, crabs were repeatedly exposed during training to a light pulse (CS) immediately followed by shock (UCS), and after a 6-h rest interval, tested with either CS-UCS or UCS. The CS-UCS presentation at testing elicited a higher recovery (potentiated recovery, circa 70%) than that evoked by the UCS alone (unconditioned recovery, circa 35%) (Experiment 3). An experiment including the explicitly unpaired control procedure (Experiment 4), confirmed that the enhanced response (CR) to the shock (UCS) (measured as potentiated recovery) is conditioned to an illumination signal (CS). An alternative explanation of the potentiated recovery in terms of retardation of habituation proved hardly tenable (Experiment 5). In Experiment 6, crabs were exposed to a variety of light pulse shock and dark pulse shock temporal relationships, and results were found consistent with a delay of reinforcement gradient when light termination was considered as CS. Thus a decrease in luminance is able to become associated with shock and to condition an enhanced response regardless of light termination being the offset of a light pulse or the onset of a dark pulse.(ABSTRACT TRUNCATED AT 250 WORDS)

Habituation and sensitization to an electrical shock in the crab Chasmagnathus. Effect of background illumination

The escape response of the crab Chasmagnathus granulatus, elicited by an electrical leg-shock, wanes as a consequence of repeated stimulation, and the decrease persists after a 24-h rest interval. Results concerning stimulus specificity in within- and between-sessions habituation strongly indicate that neither motor fatigue nor sensory adaptation nor damage can account for the response waning, which thus meets the major criteria of habituation. A comparison between the escape response habituation to leg-shock and that to a shadow passing overhead discloses clearcut differences. The shock curve shows an initial hump positively related to stimulus intensity, suggesting that a shock-induced sensitization along with habituation subserves the response curve. The curve asymptote is remarkably high and, unlike the initial waning portion, not greatly affected by treatment changes, hinting that the response may be the combination of an escape response and a basal one (an undirected burst of activity). The waning portion is higher when shocks are given in dark than when given in light, but this effect is not considered as an extra eliciting-stimulus-induced sensitization, since the reactivity enhancement depends necessarily on the darkness-shock concomitance, regardless of prior exposure to darkness. Accordingly, the hypothesis that crab habituates not only to a shock but to a complex stimulus (shock + background illumination) is put forward and discussed.

Nonhabituation processes affect stimulus specificity of response habituation in the crab Chasmagnathus granulatus

The escape response of the crab (Chasmagnathus granulatus) habituates to repeated electrical shock (SH) or to the presentation of a screen moving horizontally (H) or vertically (V) overhead. Stimulus specificity of the habituated response is shown 24 hr after training but not after either 90 or 45 min. This disruption at short intervals is explained by a transient effect that arises from training: SH training and H training attenuate and V training enhances reactivity. The attenuating effect of H training is reduced by naloxone when administered before but not after training. The results support the hypothesis that during the crab's training two types of processes takes place: a stimulus-specific, long-lasting habituation process that promotes between-sessions response habituation and a nonhabituation process that promotes nonstimulus-specific, less persistent changes of behavior that involve either response habituation or response sensitization. The effect of H training seems to be mediated by an opioid mechanism through secondary activation.