An overview of COVID-19 related to fungal infections: what do we know after the first year of pandemic?

In 2019, severe acute respiratory syndrome caused by CoV-2 virus became a pandemic worldwide, being the fast spread of the disease due to the movement of infected people from one country to another, from one continent to another, or within the same country. Associated comorbidities are important factors that predispose to any fungal coinfections. Because of the importance of fungal infections in COVID-19 patients, the aim of this work was to collect data of the more encountered mycoses related to patients undergoing this disease. Aspergillosis was the first COVID-19-related fungal infection reported, being A. fumigatus the most frequent species for CAPA. Other fungal infections related include mainly candidiasis and mucormycosis, being Rhizopus spp. the more prevalent species found. Influenza-associated pulmonary aspergillosis is well documented; thus, similar complications are expected in severe forms of COVID-19 pneumonia. Therefore, in patients with COVID-19, it is important to take special attention to the surveillance and suspicion of fungal coinfections that might worsen the patient's prognosis.

Effect of water activity and temperature on growth of ochratoxigenic strains of Aspergillus carbonarius isolated from Argentinean dried vine fruits.

Aspergillus carbonarius is an ochratoxin A (OTA) producing fungus, predominantly responsible for the production of this mycotoxin in grapes, wine and dried vine fruits. The objective of this study was to determine the in vitro effects of water activity (a(w), 0.80-0.95) and temperature (15-35 degrees C) on lag phase extension and radial growth rate of a cocktail inoculum of four strains of A. carbonarius. The maximum growth rate was observed at 0.95 a(w) and 30 degrees C (17.46 mm day(-1)). In general, growth rates increased with the increment of a(w). No growth was observed at a(w) below 0.85. For all a(w) levels tested the highest growth rate was detected at 30 degrees C. At 15 degrees C growth only occurred at the higher a(w) levels evaluated (0.925 and 0.95) at a growth rate of 3.82 and 5.57 mm day(-1) respectively. The shortest lag phase (0.26 days) was found at 0.925 a(w) and 35 degrees C. At marginal conditions of a(w) and temperature the lag phases increased, being the highest registered at 20 degrees C and 0.89 a(w) (33.7 days). The pattern of effects of environmental factors on growth was similar among Argentinean A. carbonarius strains and those from several European countries, Israel and Australia.

Role of the cardiac nerve in the effect of a novel innocuous stimulus on the heart rate of Megalobulimus mogianensis.

The effects of a brief jet of water delivered to the anterior portion of body-head on the heart rate of Megalobulimus mogianensis were determined in a group of intact snails (N = 8), previously prepared for electrocardiogram recording. The heart rate was significantly increased following stimulation. Nevertheless, with repetition of the stimulus there was a significant decrease in the magnitude of the heart rate variation and in the time for the basal heart rate to recover (first stimulus, 7.4 +/- 1.2 bpm and 15.5 +/- 1.8 min; second stimulus, 4.8 +/- 1.0 bpm and 10.6 +/- 1.5 min; third stimulus, 5.0 +/- 0.3 bpm and 11.1 +/- 1.8 min), indicating that this behavioral response undergoes early habituation. To determine the role of the cardiac nerve in mediating the heart rate alterations induced by the jet of water two other groups were tested: denervated animals (N = 8) and sham-operated control animals (N = 8). Although the innocuous stimulus caused the heart rate to increase significantly in both experimental groups, the mean increase in heart rate in denervated animals (3.2 +/- 0.4 bpm) was 41% of the value obtained in sham-operated animals (7.8 +/- 1.5 bpm), indicating that the cardiac nerve is responsible for 59% of the cardioacceleration induced by the innocuous stimulus. The increase in heart rate observed in denervated animals may be due to an increase in venous return promoted by the intense muscular activity associated with the retraction-protraction of the anterior part of the body induced by the jet of water.

Toxigenic fungi isolated from dried vine fruits in Argentina.

To evaluate the potential for mycotoxin production by fungi in dried vine fruits, the mycobiota was determined both before and after surface disinfection. Predominant genera were Aspergillus (50.2%), Eurotium (21.4%) and Penicillium (13.5%). Aspergillus section Nigri ("black aspergilli") were isolated with relatively high frequency. Aspergillus niger was the most common species but only 3 of 293 isolates screened were ochratoxin A (OTA) producers. Aspergillus carbonarius was less common but 96% of 48 strains screened were ochratoxigenic. OTA was not produced by A. japonicus. Other toxigenic fungi detected were A. ochraceus (3 strains produced OTA), Aspergillus flavus (5 strains produced cyclopiazonic acid but not aflatoxins), P. citrinum (19 strains were strong citrinin producers) and Alternaria alternata (15 strains were producers of tenuazonic acid, alternariol and alternariol methyl ether). In spite of the high incidence of A. carbonarius capable of producing OTA, low levels of this toxin were detected in the samples analysed.

The basal midbrain as a region modulating the level of alerting in the toad, Bufo paracnemis.

Reversible thiopental blockade of sites located in the basal midbrain of conscious toads bearing chronically implanted cannulae induced a response in which the animal withdrew to the bottom of the experimental box with flexed head and forelegs. Partial or total eyelid closure, myosis, and reduced ventilatory movements also occurred. No significant changes in arterial pressure levels or heart rate occurred and the reflex wiping response to the application of a painful stimulus (acid) to the skin was also unaffected. However, the somatic and visceral responses to nonpainful stimuli were reduced. There was a decrease, but not abolition, of forebrain waves in the 11 Hz range grouped in spindles, perhaps due to the reduced ventilatory drive. On the basis of these findings and of previous data from our laboratory and others on other nonmammalian groups, we postulate the existence of neurons involved in the modulation of behavioral and visceral alerting in the basal midbrain.

A technique for cardiac denervation in Megalobulimus sanctipauli (Mollusca, Gastropoda, Pulmonata).

Cardiac nerve of Megalobulimus sanctipauli can be accessed by making an incision of about 1 cm with the aid of a scalpel introduced into the connective tissue (whitish scar) joining a fold of the anterior lobe of the digestive gland. The existence of an externally identifiable anatomic characteristic (whitish scar) facilities access to the nerve thus preventing large hemolymph loss. The percentage of hits of the technique was evaluated in two different groups (N = 14 and 17) of animals, with positive results obtained for 86% and 88%, respectively. The survival rate determined 13 days after surgery for one experimental group (N = 14) was 71%.

Heart rate and behavioral patterns of Megalobulimus sanctipauli (Mollusca, Gastropoda, Pulmonata).

Adult specimens (N = 20) of the pulmonate land snail Megalobulimus sanctipauli were observed systematically in the laboratory and four behavioral patterns reflecting different degrees of activity are described. The changes in heart rate associated with different behavioral patterns were monitored using three silver chloride electrodes chronically implanted in the visceral mass of the animals (N = 13). Continuous heart rate recordings were performed at room temperature (25 degrees C) with a Nihon Kohden polygraph model RM-45. Analysis of the results by the Multiple Comparisons Test based on Friedman rank sums revealed significant differences in heart rate, reported as median, between the following behaviors: retracted into the shell and locomotion, 25 vs 35 (P less than 0.008), retracted and eating, 25 vs 38 (P less than 0.008), still with local activity and eating, 33 vs 38 (P = 0.021). These results indicate that different levels of activity have different effects on the cardiac function of Megalobulimus sanctipauli. The lowest heart rate was associated with the animal retracted into the shell. The highest rates were related to locomotion and feeding behaviors.

Heart rate and body weight alterations in juvenile specimens of the tropical land snail Megalobulimus sanctipauli during dormancy.

The time course of heart rate and body weight alterations during the natural period of dormancy were determined in active feeding and dormant juvenile specimens of Megalobulimus sanctipauli. In both groups, heart rate markedly decreased during the first 40 days of dormancy, tending to stabilize thereafter. This time period coincided with the decrease in environmental temperature during autumn-winter. At the end of the dormancy period, surviving active feeding and dormant snails showed a significant decrease in heart rate which, however, was significantly greater in the latter group. Total body weight decreased concomitantly with heart rate in dormant snails but remained constant in active feeding snails. Body hydration induced significant increases in weight and heart rate in surviving dormant snails. Feeding following hydration promoted a new significant increase in heart rate but not in weight. These results indicate that the decrease in heart rate observed in juvenile specimens of M. sanctipauli during dormancy may be due to at least three factors: 1) decrease in environmental temperature during autumn-winter, 2) starvation which leads to the depletion of endogenous fuel reserves and to a probable decrease in hemolymph nutrient levels, and 3) dehydration which leads to a probable decrease in hemolymph volume and venous return and/or to an increase in hemolymph osmolarity.

Role of the cardiac nerve in the adaptive changes of heart rate in response to an aversive stimulus in Megalobulimus mogianensis.

The effect of an aversive stimulus represented by contact with a hot plate on the heart rate of Megalobulimus mogianensis was evaluated with electrocardiogram recording in intact snails (N = 8). All stimulated animals showed an increase in heart rate, with mean values ranging from 35.6 +/- 1.2 (basal heart rate) to 43.8 +/- 0.9 bpm (post-stimulation heart rate). The cardioacceleration was followed by gradual recovery of the basal heart rate, with mean recovery times varying from 4.3 +/- 0.3 to 5.8 +/- 0.6 min. Repetition of the stimulus did not affect the magnitude of variation nor did it influence the basal heart rate recovery time. To investigate the role of the cardiac nerve in mediating the heart rate alterations induced by the aversive stimulus, denervated (N = 8) and sham-operated (N = 8) animals were also tested. Although the aversive stimulus caused the heart rate to increase significantly in both experimental groups, the mean increase in heart rate in denervated animals (4.4 +/- 0.4 bpm) was 57% of the value obtained in sham-operated animals (7.7 +/- 1.3 bpm), indicating that the cardiac nerve is responsible for 43% of the cardioacceleration induced by the aversive stimulus. The cardioacceleration observed in denervated snails may be due to an increase in venous return promoted by the intense muscular activity associated with the withdrawal response. Humoral factors may also be involved. A probable delaying inhibitory effect of the cardiac nerve on the recuperation of the basal heart rate is suggested.

Effect of the dry-cold season dormancy on the tonic and phasic neural control of heart rate in the toad, Bufo paracnemis.

This work examined basal heart rate and autonomic cardiac tone as well as sympathetic cardiac reactivity to hypotension induced by systemic nitroprusside injection in dormant toads (dry-cold season), Bufo paracnemis, comparing the values with those of toads collected during the active months (hot-rainy season). Autonomic tone was calculated according to the method of Lin and Horwath ('72), which allows its evaluation as a percentage of intrinsic heart rate. Specimens were maintained in an outdoors terrarium except for the week preceding surgery, when they were transferred to indoor nonclimatized tanks. The heart rate of dormant toads (27.8 +/- 2.7 beats/min) was lower than that of active toads at rest (38.6 +/- 2. 3). Cholinergic tone was higher than adrenergic tone both in active (26.2% and 7.8%, respectively) and aestivated (19.5% and 4.8%, respectively) animals. Thus, cholinergic tone and adrenergic tone were both lower in dormant animals. The reflex tachycardia elicited by nitroprusside-induced hypotension was lower in aestivated toads (9.3 +/- 0.9 beats/min) when compared to active toads (19.9 +/- 1.0), indicating a reduced sympathetic reactivity. Nitroprusside-induced hypotensions were not different in the two groups. We conclude that at rest Bufo paracnemis heart is under the influence of a double cholinergic and adrenergic tone, and that both influences, as well as the reflex adrenergic reactivity to the unloading produced by nitroprusside-induced hypotension, are reduced in aestivated toads.

Heart rate and temperature in the snail Megalobulimus sanctipauli: role of the cardiac nerve.

The effects of five levels of temperature (15, 20, 25, 30, and 35 degrees C) on the heart rate of Megalobulimus sanctipauli were determined in a group of intact snails (n = 8). The results indicate that heart rate increased almost linearly with temperature over the tested range. The average Q10 calculated for the 15 to 25 degrees C range (1.9) did not differ from that calculated for the 25 to 35 degrees C range (1.7). To investigate the role of the cardiac nerve in mediating these heart rate alterations two others groups were tested: denervated animals (n = 8) and sham-operated control animals (n = 8). The results showed that the relationship between heart rate and each temperature level was not altered by cutting the visceral nerve that innervates the heart, indicating that the nervous system is not implicated in the increase in heart rate induced by increasing temperature. These changes in heart rate are probably due to a direct action of temperature on heart muscle by accelerating the myogenic self-excitation process.

Agonistic behavior and its cardiovascular components elicited by microinjection of L-glutamic acid into the basal midbrain of the toad Bufo paracnemis.

Microinjection of L-glutamic acid into the basal midbrain of the toad Bufo paracnemis induced a series of responses linked to antipredator behavior such as flight, backward locomotion and defensive postures. Furthermore, alerting/orientation occurred in 20% of the animals, a behavior which is probably important for the animal to achieve the above responses. Locomotion occurred in 18% of the toads. The existence of a mesencephalic premotor control for locomotion in these animals is discussed comparatively. All responses were accompanied by changes in arterial pressure, heart rate and intrabuccal pressure. In some animals which exhibited backward locomotion responses, defensive postures and alerting/orientation, bradycardia or cardiac arrest occurred, with no appreciable changes in arterial pressure. This fact is discussed on the basis of studies which have shown the occurrence of similar alterations in situations of fear in other vertebrates. Autonomic changes without other responses occurred in 16% of the animals. Flight behavior was usually observed as a consequence of stimulation of sites located in the anterodorsal tegmental nucleus and lateral portions of the midbrain tegmentum. In contrast, locomotion was obtained by stimulating basal sites of the tegmentum located in the anteroventral nucleus and in the reticular formation lateral to it. Sites related to the remaining behaviors were located more diffusely in the basal midbrain.

Role of the cardiac nerve in the adaptive changes of heart rate in response to an aversive stimulus in Megalobulimus mogianensis

The effect of an aversive stimulus represented by contact with a hot plate on the heart rate of Megalobulimus mogianensis was evaluated with electrocardiogram recording in intact snails (N = 8). All stimulated animals showed an increase in heart rate, with mean values ranging from 35.6 ± 1.2 (basal heart rate) to 43.8 ± 0.9 bpm (post-stimulation heart rate). The cardioacceleration was followed by gradual recovery of the basal heart rate, with mean recovery times varying from 4.3 ± 0.3 to 5.8 ± 0.6 min. Repetition of the stimulus did not affect the magnitude of variation nor did it influence the basal heart rate recovery time. To investigate the role of the cardiac nerve in mediating the heart rate alterations induced by the aversive stimulus, denervated (N = 8) and sham-operated (N = 8) animals were also tested. Although the aversive stimulus caused the heart rate to increase significantly in both experimental groups, the mean increase in heart rate in denervated animals (4.4 ± 0.4 bpm) was 57 percent of the value obtained in sham-operated animals (7.7 ± 1.3 bpm), indicating that the cardiac nerve is responsible for 43 percent of the cardioacceleration induced by the aversive stimulus. The cardioacceleration observed in denervated snails may be due to an increase in venous return promoted by the intense muscular activity associated with the withdrawal response. Humoral factors may also be involved. A probable delaying inhibitory effect of the cardiac nerve on the recuperation of the basal heart rate is suggested.

Role of the cardiac nerve in the effect of a novel innocuous stimulus on the heart rate of Megalobulimus mogianensis

The effects of a brief jet of water delivered to the anterior portion of body-head on the heart rate of Megalobulimus mogianensis were determined in a group of intact snails (N = 8), previously prepared for electrocardiogram recording. The heart rate was significantly increased following stimulation. Nevertheless, with repetition of the stimulus there was a significant decrease in the magnitude of the heart rate variation and in the time for the basal heart rate to recover (first stimulus, 7.4 ± 1.2 bpm and 15.5 ± 1.8 min; second stimulus, 4.8 ± 1.0 bpm and 10.6 ± 1.5 min; third stimulus, 5.0 ± 0.3 bpm and 11.1 ± 1.8 min), indicating that this behavioral response undergoes early habituation. To determine the role of the cardiac nerve in mediating the heart rate alterations induced by the jet of water two other groups were tested: denervated animals (N = 8) and sham-operated control animals (N = 8). Although the innocuous stimulus caused the heart rate to increase significantly in both experimental groups, the mean increase in heart rate in denervated animals (3.2 ± 0.4 bpm) was 41 percent of the value obtained in sham-operated animals (7.8 ± 1.5 bpm), indicating that the cardiac nerve is responsible for 59 percent of the cardioacceleration induced by the innocuous stimulus. The increase in heart rate observed in denervated animals may be due to an increase in venous return promoted by the intense muscular activity associated with the retraction-protraction of the anterior part of the body induced by the jet of water.

Heart rate and body weight alterations in juvenile specimens of the tropical land snail Megalobulimus sanctipauli during dormancy

The time course of heart rate and body weight alterations during the natural period of dormancy were determined in active feeding and dormant juvenile specimens of Megalobulimus sanctipauli. In both groups, heart rate markedly decreased during the first 40 days of dormancy, tending to stabilize thereafter. This time period coincided with the decrease in environmental temperature during autumn-winter. At the end of the dormancy period, surviving active feeding and dormant snails showed a significant decrease in heart rate which, however, was significantly greater in the latter group. Total body weight decreased concomitantly with heart rate in dormant snails but remained constant in active feeding snails. Body hydration induced significant increases in weight and heart rate in surviving dormant snails. Feeding following hydration promoted a new significant increase in heart rate but not in weight. These results indicate that the decrease in heart rate observed in juvenile specimens of M. sanctipauli during dormancy may be due to at least three factors: 1) decrease in environmental temperature during autumn-winter, 2) starvation which leads to the depletion of endogenous fuel reserves and to a probable decrease in hemolymph nutrient levels, and 3) dehydration which leads to a probable decrease in hemolymph volume and venous return and/or to an increase in hemolymph osmolarity

A technique for cardic denervation in Megalobulimus sanctpaului (mollusca, gastropoda, pulmonata)

Cardiac nerve of Megalobulinus sanctipauli can be accessed bu making an incision of about 1 cm with the aid of scalpel introduced into the connective tissue (whitsh car) joining a fold of the anterior lobe of the digestive gland. The existence of an externally identifiable anatomic characteristic (whitish scar) faciliates access to the nerve thus preventing large hemolymph loss. The percentage of hits of the technique was evauated in two different groups (N = 14 and 17) of animals, with positive results obtained for 86% and 88%, respectively. The survival rate determined 13 days after surgery for one experimental group (N = 14 was 71%