High prevalence of asymptomatic COVID-19 in hemodialysis. Daily learning during first month of COVID-19 pandemic☆

Dialysis patients are a risk group for SARS-CoV2 infection and possibly further complications, but we have little information. The aim of this paper is to describe the experience of the first month of the SARS-Cov2 pandemic in a hospital haemodialysis (HD) unit serving the district of Madrid with the second highest incidence of COVID19 (almost 1000 patients in 100,000 h). In the form of a diary, we present the actions undertaken, the incidence of COVID19 in patients and health staff, some clinical characteristics and the results of screening all the patients in the unit.

We started with 90 patients on HD: 37 (41.1%) had COVID19, of whom 17 (45.9%) were diagnosed through symptoms detected in triage or during the session, and 15 (40.5%) through subsequent screening of those who, until that time, had not undergone SARS-CoV2 PCR testing. Fever was the most frequent symptom, 50% had lymphopenia and 18.4% <95% O₂ saturation. Sixteen (43.2%) patients required hospital admission and 6 (16.2%) died. We found a cluster of infection per shift and also among those using public transport. In terms of staff, of the 44 people involved, 15 (34%) had compatible symptoms, 4 (9%) were confirmed as SARS-Cov2 PCR cases by occupational health, 9 (20%) required some period of sick leave, temporary disability to work (ILT), and 5 were considered likely cases.

Conclusions

We detected a high prevalence of COVID19 with a high percentage detected by screening; hence the need for proactive diagnosis to stop the pandemic. Most cases are managed as outpatients, however severe symptoms are also appearing and mortality to date is 16.2%. In terms of staff, 20% have required sick leave in relation to COVID19.

Context-dependent effects of yolk androgens on nestling growth and immune function in a multibrooded passerine

Female birds may adjust their offspring phenotype to the specific requirements of the environment by differential allocation of physiologically active substances into yolks, such as androgens. Yolk androgens have been shown to accelerate embryonic development, growth rate and competitive ability of nestlings, but they can also entail immunological costs. The balance between costs and benefits of androgen allocation is expected to depend on nestling environment. We tested this hypothesis in a multibrooded passerine, the spotless starling, Sturnus unicolor. We experimentally manipulated yolk androgen levels using a between-brood design and evaluated its effects on nestling development, survival and immune function. Both in first and replacement broods, the embryonic development period was shorter for androgen-treated chicks than controls, but there were no differences in second broods. In replacement broods, androgen-treated chicks were heavier and larger than those hatched from control eggs, but this effect was not observed in the other breeding attempts. Androgen exposure reduced survival with respect to controls only in second broods. Regarding immune function, we detected nonsignificant trends for androgen treatment to activate two important components of innate and adaptive immunity (IL-6 and Ig-A levels, respectively). Similarly, androgen-treated chicks showed greater lymphocyte proliferation than controls in the first brood and an opposite trend in the second brood. Our results indicate that yolk androgen effects on nestling development and immunity depend on the environmental conditions of each breeding attempt. Variation in maternal androgen allocation to eggs could be explained as the result of context-dependent optimal strategies to maximize offspring fitness.

White adipose tissue production and release of IL-6 and TNF-alpha do not parallel circulating and cerebrospinal fluid concentrations in pregnant rats

IL-6 and TNF-alpha are synthesized in white adipose tissue both by adipocytes and by the stroma-vascular fraction. They both are known to interfere with insulin signaling, reducing insulin sensitivity and lipid deposition. At a central level, IL-6 enhances sympathetic nervous system activity, thus enhancing lipolysis and reducing fat mass. During late pregnancy, white adipose tissue (WAT) mass increases and insulin sensitivity decreases. To assess the involvement of both adipokines in such processes, we analyzed the tissue content and release of both adipokines in parametrial and subcutaneous WAT depots and their circulating and cerebrospinal fluid concentrations in nonpregnant rats and in pregnant rats by days 8, 15, and 19 of pregnancy. The tissue content of both adipokines was enhanced 5-6 times by day 8 until the end of pregnancy in parametrial WAT, whereas the increase took place by day 15-19 in subcutaneous WAT. No increase in tissue release was detected, suggesting a local action. However, circulating IL-6 concentration was enhanced by day 8 until the end of pregnancy, suggesting sources other than WAT. IL-6 concentration in cerebrospinal fluid paralleled the increases in serum by days 8 and 15, suggesting a systemic origin. However, it returned to basal levels by day 19, suggesting a central control for IL-6 entrance. TNF-alpha was not detected in either serum or cerebrospinal fluid. These results led us to conclude that across pregnancy adipokines control WAT depots in a time- and depot-dependent manner. They do so directly, by local production, but the enhanced concentrations of both circulating and CSF IL-6 suggest an indirect action mediated by the nervous system.

[Peripheral vascular disease: prevalence, mortality and relationship with inflammation in hemodialysis]

Peripheral vascular disease (PVD) is a common disease among patients undergoing hemodialysis leading to increase morbidity and mortality with a high risk of inflammation and sepsis. The aim of the present study was to determinate PVD prevalence in our hemodialysis population and association with inflammation. The study sample consisted of 220 patients prevalents in hemodialysis. A basal study was made in 2001 and a follow up for 47 months. Data were collected retrospectively. PVD diagnosis was made attending to limb pulses and doppler in revisions. Diagnosis was classified as rest pain, ischemic ulceration and gangrene. Among a total of 220 patients, 89 had prevalent PVD. Thirty per cent had rest pain, 6,5% had ischemic ulceration and 3% had gangrene. Ninety five per cent underwent medical treatment, 0,5% were treated by percutaneous transluminal angioplasty (PTA), 2% were treated with surgical revascularization and 2,5% were treated with amputation. Patients with PVD were older, with higher Charlson index, diabetes, they hay higher CRP and fibrinogen serum levels; and lower albumin and prealbumine serum levels. Survival PVD was decreased in Kaplan-Meier (log rank =12,4; p<0,000). Adjusted Cox regression analysis revealed that PVD (p =0,034; OR =2,10; IC [1,06 ; 4,23]) ; age (p =0,001; OR =1,06; IC [1,03 ; 1,09]) and low serum albumin levels (p =0,012; OR =0,93; IC [0,89 ; 0,98]) predicted significantly the risk of mortality. PVD is an independent mortality risk factor in hemodialysis patients. An early diagnosis and treatment are able with examination and doppler. In our sample, a few patients are treated with PTA or surgical revascularization. There is an association between PVD and inflammation.

Control by reproduction-related hormones of resistin expression and plasma concentration

Although not simultaneously, resistin expression in white adipose tissue (WAT) and resistin plasma concentration have been shown to increase in pregnant rats. To clarify the involvement of sex hormones in such increases, we administered for 3-5 days progesterone, estradiol, or human chorionic gonadotropin (hCG) to female rats in dioestrus II. Progesterone increased resistin expression retroperitoneal WAT but lacked effect in parametrial or subcutaneous depots. It also increased resistin plasma concentration. Estradiol decreased resistin expression in both parametrial and inguinal WAT but was without effect on retroperitoneal depots. It did not alter plasma resistin. Human hCG increased resistin expression in all the visceral depots examined - parametrial, inguinal and retroperitoneal - but did not change plasma resistin. These results show that hormonal influences in resistin expression are depot-dependent and can run separately from changes in its plasma concentration. Besides, the locally restricted effect of progesterone in resistin expression compared with that of hCG suggests it is not the only hormone enhancing resistin expression in early pregnancy. However, it could enhance resistin release in late pregnancy. Estradiol could be involved in the decrease of resistin expression in late pregnancy. Finally, since hCG acts through LH receptors, our results suggest that they are present in WAT and that they control resistin expression.

Kidney Transplantation With Grafts From Non–Heart-Beating Donors

We analyzed the function and outcome of 16 kidney transplants performed in our hospital from non-heart-beating donors who were harvested at other hospitals. The cold ischemia times were longer and the delayed graft function rates higher. However, graft function was no different from that of kidneys from heart-beating donors. This experience has encouraged us to use this type of donor to reduce the transplant waiting list.

Adiponectin values are unchanged during pregnancy in rats

Adiponectin is believed to be a key factor in determining insulin sensitivity. In turn, insulin sensitivity is known to change from an enhanced state in early pregnancy to a reduced one in late pregnancy. A role for adiponectin in these changes has been proposed for mice but questioned for humans. We addressed this issue in rats by measuring adiponectin expression in both visceral and subcutaneous white adipose tissue, together with tissue content and release of the hormone in non-pregnant and in pregnant rats by days 8, 15 and 19 of pregnancy. Plasma concentration was also determined. No differences were found in any of the parameters measured between non-pregnant and pregnant rats at any time of pregnancy despite changes in white adipose tissue mass and insulin sensitivity. Adiponectin was also detected in cerebrospinal fluid at a concentration 1,000 times lower than in plasma, but again no differences were found between non-pregnant and pregnant animals. It is concluded that adiponectin does not play any role in regulating changes in insulin sensitivity during pregnancy in rats.

Effect of acute cold exposure on the expression of the adiponectin, resistin and leptin genes in rat white and brown adipose tissues

Leptin, adiponectin, and resistin are key hormones produced by adipose tissue. In the present study, we have examined the effects of acute cold exposure (18 h at 6 degrees C) on the expression of the genes encoding these hormones in both brown and white fat of rats. Acute cold exposure resulted in a significant (p < 0.001) increase in the level of UCP1 and metallothionein-1 mRNAs in brown adipose tissue, indicative of an activation of thermogenesis. Leptin mRNA was decreased (p < 0.001) in brown fat in the cold, and there was also a small but statistically significant (p < 0.05) decrease in adiponectin mRNA; resistin mRNA did not change significantly (p > 0.05). In white fat, the level of leptin mRNA also fell in the cold (p < 0.05), but there was no significant change (p > 0.05) in either adiponectin or resistin mRNA. The serum concentration of adiponectin was unchanged following acute cold exposure. We conclude that while leptin gene expression is inhibited by exposure to cold, there is no major effect on the expression of either the adiponectin or resistin genes in white or brown fat despite the cold-induced stimulation of sympathetic activity and fatty acid flux. Thus, adiponectin and resistin are unlikely to play a key role in the extensive metabolic adaptations to cold.

The anorectic effect of oestradiol does not involve changes in plasma and cerebrospinal fluid leptin concentrations in the rat

Oestradiol is a potent anorectic agent that reduces both food intake and body weight. Since leptin is known to reduce food intake, we first analysed if the anorectic effect of oestradiol is driven by an increased leptin concentration in either cerebrospinal fluid or plasma. Oestradiol also reduces body weight and fat mass. Accordingly, a decrease in plasma leptin concentration can also be expected after an oestradiol-driven reduction in fat mass. To test this hypothesis was the second aim of this study. Female Wistar rats received oestradiol chronically during 14 days. During the first week of treatment there was a reduction in food intake, body weight and fat mass that returned to initial values during the second week, but no changes in ob mRNA levels were found in white adipose tissue depots. There was no effect of treatment or time on plasma and cerebrospinal fluid leptin concentrations. Therefore, the anorectic effect of oestradiol is not driven by an increase in leptin concentration either in plasma or in cerebrospinal fluid, and the reduction in fat mass that oestradiol produces is not followed by a reduction leptin concentration.

Oestradiol and progesterone change beta3-adrenergic receptor affinity and density in brown adipocytes

OBJECTIVE

To check if the oestradiol- and progesterone-driven reduction in noradrenaline responsiveness of brown adipocytes is due to a reduction in either the density or the affinity of beta3-adrenoceptors (beta3-AR). beta1/beta2-AR were also studied.

DESIGN

Four groups of animals were considered. (i) control rats at thermoneutrality, (ii) cold-acclimated rats, to determine beta-AR under continuous sympathetic stimulation, which is known to decrease noradrenaline responsiveness, (iii) oestradiol- and (iv) progesterone-treated cold-acclimated rats to determine hormonal effects on beta-AR populations in thermogenically active brown adipocytes.

METHODS

Oestradiol and progesterone were chronically elevated by means of s.c. Silastic implants. Densities and affinities of beta-AR populations were determined by binding studies using [3H]CGP-12177 as radioligand.

RESULTS

Two populations of low and high binding affinities (K(d) 1.6 and 27.3 nmol/l) corresponding to beta3- and beta1/beta2-AR respectively were found at thermoneutrality. beta3-AR density was higher than that of beta1/beta2-AR (B(max) 419 and 143 fmol/mg protein respectively). Cold-acclimated rats showed a reduction of beta3-AR binding capacity (B(max) 308 fmol/mg protein). Oestradiol and progesterone reduced the density of beta3-AR to 167 and 185 fmol/mg protein respectively, while increasing their affinity for [3H]CGP-12177 (K(d) 9.5 and 4.0 nmol/l vs 16 nmol/l in cold-acclimated untreated rats). The density of beta1/beta2-AR was also reduced after oestradiol treatment (B(max) 51 fmol/mg protein).

CONCLUSIONS

Both oestradiol and progesterone reduce the density of beta3-AR in brown adipose tissue (BAT) while increasing their affinity for [3H]CGP-12177. Oestradiol also reduces the density of beta1/beta2-AR whereas cold-acclimation reduces the density of beta3-AR.

Plasma and cerebrospinal fluid leptin levels are maintained despite enhanced food intake in progesterone-treated rats

OBJECTIVES

For adipostatic control, increases in food intake are followed by increased leptin levels that in turn reduce food intake. However, progesterone administration increases both food intake and body weight. The aim of this study was to analyze changes in the white adipose tissue-leptin system in rats with enhanced plasma levels of progesterone.

METHODS

Female Wistar rats received progesterone chronically by means of subcutaneous implants over 30 days.

RESULTS

They showed an increased food intake followed by increased body weight and heavier fat depots. An enhanced ob-mRNA level was detected in inguinal white adipose tissue depot on day 2 of treatment but the increase was transient, disappearing on day 6 of treatment. No changes in ob-mRNA levels were found in parametrial and retroperitoneal white adipose tissue depots. Plasma and cerebrospinal fluid leptin levels were unchanged either during the treatment or between corresponding treated and control rats. Leptin concentrations in cerebrospinal fluid were ten times lower than in plasma (0.2--0.3 ng/ml versus 2--3 ng/ml respectively).

CONCLUSIONS

These results indicated that progesterone favours a positive energy balance not only by enhancing food intake but also by inhibiting the concurrent enhancement in plasma and cerebrospinal fluid leptin levels expected from the increased fat mass.

Dual control of cytochrome-c oxidase activity by female sex steroids

Female sex steroids modify cytochrome-c oxidase (COX) activity in brown adipose tissue. To check the possibility of extending this modulating effect upon oxidative capacity to other tissues, COX activity was measured in different tissues from cold-acclimated female rats that were (1) intact in proestrus and diestrus I, (2) ovariectomized or (3) ovariectomized and treated with oestradiol and/or progesterone. In intact rats, COX activity varied within the oestrous cycle in brown adipose tissue and soleus muscle. Ovariectomy induced an increase in COX activity in most of the tissues studied, an increase reversed only after 10 days of treatment with oestradiol and/or progesterone. These results indicate both a short-term (oestrous cycle) and a long-term (ovariectomy) control of COX activity by female sex steroids, probably mediated by allosteric modulation and control of the enzyme synthesis respectively. In thermogenic tissues, that is brown adipose tissue and skeletal muscles, the short-term control is interpreted as a cooperation between tissues to fulfil the requirements of temperature maintenance.

Changes in cytochrome oxidase activity in brown adipose tissue during oestrous cycle in the rat

Cold-acclimated female Wistar rats were killed at a known phase of the oestrous cycle to investigate whether natural fluctuations of female sex steroids during the cycle are mirrored by changes in brown adipose tissue (BAT) activity. Four phases: proestrus, oestrus, dioestrus I and dioestrus II, were identified by the cells types appearing in vaginal smears. BAT was removed and analysed for composition and specific indicators of BAT activity. No changes in BAT mass, protein or mitochondrial content were detected during the cycle. Thermogenesis was also unchanged as judged by both lipid multilocularity and mitochondrial GDP-binding. However, cytochrome c oxidase (COX) activity did cycle with a minimum at proestrus and a maximum at dioestrus I. The involvement of oestradiol in such a cycle is suggested by the fact that oestradiol treatment decreased COX activity to values similar to those found in proestrus. The physiological function of a cyclic oxidative capacity remains to be elucidated.

Short-term treatment with oleoyl-oestrone in liposomes (Merlin-2) strongly reduces the expression of the ob gene in young rats

Young female rats of 160-180 g were implanted with osmotic minipumps releasing 3.0 micromol/day per kg of oleoyl-oestrone in liposomes (Merlin-2) into the bloodstream for up to 14 days. Merlin-2 induced a loss of appetite in the first days, later recovered, and a decrease in body weight of 7%, which contrasts with the 15% increase in controls during the 2-week period. Neither plasma glucose nor urea was affected by treatment, but liver glycogen increased by 50% in 14 days. Insulin decreased slightly with Merlin-2 treatment. Plasma corticotropin (ACTH) and corticosterone showed a transient increase by day 6 of treatment. The expression of the ob gene in adipose tissue fell during the period studied to practically nil on day 14; circulating leptin levels decreased more than 70% from day 1 to day 14. Oestrone levels increased from 0.3 nM (controls) to a maintained 40-60 nM level for the rest of the experiment. Oleoyl-oestrone levels first increased 4-fold, to decrease again to the initial levels on day 10, increasing later to 100-fold on day 14. The three phases observed in food intake, weight loss and oleoyl-oestrone levels match fairly well, which supports the direct involvement of oleoyl-oestrone in body-weight control. However, the control of oleoyl-oestrone levels seems to be mediated in part by corticosterone. The practical disappearance of leptin synthesis coincides with the massive accumulation of oleoyl-oestrone in plasma. The results presented suggest the involvement of oleoyl-oestrone in the main mechanisms of control of body weight and its regulation by glucocorticoids and leptin.

Food intake and body weight in rats with daily food-availability restrictions

Male Wistar rats were offered food for either 24, 6, or 1 h a day at two different ambient temperatures -21 or 6 degrees C. At room temperature, rats offered food for 6 h a day matched their food intake to that of rats with 24 h of food-availability in 2-3 days, so that no main changes in total food intake, gross food efficiency, and body weight were recorded. No impairment of thermoregulatory capacity was recorded as judged by the unaltered oxidative capacity of brown adipose tissue and skeletal muscle. Nonetheless, a transient hypothermia was recorded at the beginning of the experiment in the food-restricted group. Rats that were only offered food 1 h a day were unable to sustain the food intake of the control animals, so that a continuous decline in body weight and a negative gross food efficiency ensured. In the cold, the food intake of rats offered food for only 6 or 1 h a day was similar to that showed by the corresponding groups at 21 degrees C. These results suggest a maximum rate for digestive processes, irrespective of ambient temperature. However, such levels of food intake were clearly insufficient to cope with the thermoregulatory enhanced energy demand at 6 degrees C, ad judged by the decrease in body weight.

Progesterone does not alter sympathetic activity in tissues involved in energy balance

Female rats acclimated to thermoneutrality to avoid cold influences received progesterone by means of subcutaneous implants. They increased their food intake and body weight above the values recorded in control animals. None the less, despite the enhanced food intake, no sign of activation of the sympathetic nervous system was observed, as judged by the unaltered noradrenaline content, half-life and turnover rate in brown adipose tissue, pancreas and heart. This indicates that progesterone increases food intake but prevents non-energy-conservation processes regulated by the sympathetic nervous system from taking place. Thus, it facilitates in two different ways the building up of energy stores. Because overfeeding induced by palatable diets increases the sympathetic tone to the organs studied, it is suggested that the central mechanisms regulating energy balance are probably influenced in a different manner by progesterone than by the sensory properties of palatable diets.

Reduced oxygen consumption of brown adipocytes isolated from progesterone-treated rats

It has been previously shown that responsiveness to noradrenaline is reduced in brown adipocytes isolated from estradiol-treated rats. The possibility that high plasma levels of progesterone could also alter adrenergic response was checked. The oxygen consumption of brown adipocytes isolated from control and progesterone-treated rats was monitored in basal conditions and in the presence of increasing concentrations of noradrenaline. In both situations, cells isolated from treated animals showed a lower respiratory rate than those from control animals. These results suggest that not only estradiol but also progesterone could modulate the adrenergic response of brown adipocytes. The study of alpha 1- and beta-adrenergic responses indicates that the beta-response parallels the general reduction in oxygen consumption, although the alpha 1-response seems to be more deeply depressed. Estimation of cell number in brown fat depots indicates some hyperplasia induced by progesterone; this increase in cell number could counterbalance partially but not totally the decreased cellular oxygen consumption at the organ level.

Oxygen consumption of oestradiol-treated rats

Rectal temperature and oxygen consumption (Vo2) were monitored in female rats acclimated either to cold or to thermoneutrality and with and without chronic administration of oestradiol. The hormone is known to inactivate brown adipose tissue (BAT) and to reduce its response to noradrenaline (NA). The role of sympathetic control was studied by administering NA or the adrenergic blocker propranolol. Oestradiol treatment did not affect rectal temperature in the states of acclimation to thermoneutrality and to cold, nor did it change the hypothermic response of cold-exposed rats to temporary food deprivation. In the cold-acclimated rats, both controls and oestradiol-treated animals exhibited similar degrees of metabolic reduction after propranolol administration in the cold and similar degrees of metabolic activation by NA at thermoneutrality. Rats acclimated to thermoneutrality showed a larger metabolic response to NA when treated with oestradiol. The results suggest that oestradiol, while inactivating the BAT response to NA, activates the NA responsiveness of other metabolically active tissues in cold-induced thermogenesis. The observation of a greater oxidative capacity in the kidney and the rectus abdominis muscle of oestradiol-treated, cold-acclimated rats would be in line with this proposal.

Dissociation between brown adipose tissue thermogenesis and sympathetic activity in rats with high plasma levels of oestradiol

It has been shown previously that high plasma levels of oestradiol inhibit brown adipose tissue thermogenesis. Since rats and mice show a close association between thermogenic activity in and sympathetic discharge to brown fat, we measured the noradrenaline turnover in rats with high plasma levels of oestradiol to establish whether the observed inhibition of thermogenic activity is brought about by a reduction in the sympathetic drive to brown adipocytes. Oestradiol-filled Silastic capsules were implanted subcutaneously in female rats previously acclimated either to thermoneutrality or to cold. Control rats received empty implants. After 15 days treatment, noradrenaline turnover was measured by blocking its synthesis with alpha-methyl-p-tyrosine. As expected, noradrenaline turnover was higher in cold-acclimated rats than in rats kept at thermoneutrality. The presence of high plasma oestradiol levels did not alter sympathetic activity in any of the treated groups despite reducing thermogenic activity. This result reveals that oestradiol dissociates the thermogenic activity of brown adipose tissue from its sympathetic activation. Such dissociation has never been previously reported in rats, although it seems to be common in Syrian hamsters. However the causative factor in this species is unknown.

Reduced noradrenaline responsiveness of brown adipocytes isolated from estradiol-treated rats

High plasma levels of estradiol are known to reduce the GDP binding of brown adipose tissue. Since GDP binding depends on the level of sympathetic discharge to brown adipose tissue, we measured the responsiveness to noradrenaline of brown adipocytes isolated from female rats with high plasma levels of estradiol. Noradrenaline responsiveness was assessed by measuring the respiration rate of isolated brown adipocytes in the presence of different concentrations of noradrenaline. Both control and treated adipocytes showed the same basal respiratory rate (27 +/- 6 and 24 +/- 4 nmol O2.min-1.10(-6) cells, respectively). The presence of noradrenaline (0.1, 1, and 10 microM) in the medium increased the respiration rate of both kinds of adipocytes in a dose-dependent manner. However, the response was markedly reduced in adipocytes isolated from estradiol-treated rats. These results suggest that estradiol impairs the responsiveness of brown adipose tissue to the sympathetic nervous system. Three possible mechanisms are suggested as accounting for the observed decreased responsiveness to noradrenaline, i.e., a direct action of estradiol in brown adipocytes, a modulatory role of estradiol in the central control of the sympathetic discharge to brown adipose tissue, and the interference of catecholestrogens with noradrenaline synthesis at the sympathetic terminals.

Brown adipose tissue thermogenesis above the lower critical temperature

Heat-acclimated rats show lighter IBAT deposit with different gross composition and lower GDP-binding than controls at thermoneutrality. A thermal disactivation of the tissue is then inferred. Cafeteria regime increased IBAT mass and GDP-binding when offered to rats at a thermoneutral ambient temperature. These results indicate that BAT thermogenesis at thermoneutrality is not the lowest one of the tissue and that diet-induced thermogenesis can take place even at thermoneutrality.