Short-term exposure to high relative humidity increases blood urea and influences colonic urea-nitrogen metabolism by altering the gut microbiota

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Plasma urea was increased along with erythrocyte Na⁺/K⁺ -ATPase activity reduced and abnormal erythrocyte morphologies appeared during 14-day high relative humidity (90 ± 2%) exposure.

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Shortly after 12-h and 24-h exposures, urea influx and ammonia level were increased in the colon of mice, respectively.

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Colonic urea-nitrogen metabolism was influenced by the increased levels of ammonia, amino acids and short-chain fatty acids during 14-day exposure.

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Gut bacteria related to urease production, amino acids metabolism and SCFAs production was enriched during the exposure.

Introduction

Colonic urea-nitrogen metabolites have been implicated in the pathogenesis of certain diseases which can be affected by environmental factors.

Objectives

We aimed to explore the influence of ambient humidity on colonic urea-nitrogen metabolism.

Methods

Blood biochemical indexes, metabolites of intestinal tract, and gut microbiota composition of mice (n = 10/group) exposed to high relative humidity (RH, 90 ± 2%) were analyzed during the 14-day exposure.

Results

After 12-h exposure, plasma blood urea nitrogen (BUN) level increased along with a decrease in the activity of erythrocyte Na⁺/K⁺ -ATPase. Moreover, abnormal erythrocyte morphologies appeared after 3 days of exposure. The colonic BUN and ammonia levels increased significantly after the 12-h and 24-h exposure, respectively. The colonic level of amino acids, partly synthesized by gut microbiota using ammonia as the nitrogen source, was significantly higher on the 7th day. Furthermore, the level of fecal short-chain fatty acids was significantly higher after 3-day exposure and the level of branched-chain fatty acids increased on the 14th day. Overall, gut microbiota composition was continuously altered during exposure, facilitating the preferential proliferation of urea-nitrogen metabolism bacteria.

Conclusion

Our findings suggest that short-term high RH exposure influences colonic urea-nitrogen metabolism by increasing the influx of colonic urea and altering gut microbiota, which might further impact the host health outcomes.

Inappropriate Secretion of Antidiuretic Hormone after Pancreatoduodenectomy for Pancreatic Head Cancer: A Case Report and Literature Review

Syndrome of inappropriate secretion of antidiuretic hormone (SIADH) is a disease that leads to dilute hyponatremia through excessive secretion of antidiuretic hormone. SIADH has various causes, including ectopic ADH-producing tumors, drug properties, and can be idiopathic. But there have been very few reports of cases in which SIADH has developed after surgery for malignant tumors. In addition, few cases have been reported where this disease has developed after surgery for pancreatic cancer, because the symptoms of hyponatremia are non-specific. These symptoms are particularly gastrointestinal symptoms; therefore, it is difficult to differentiate them, even if SIADH has developed after gastrointestinal surgery. The patient in our case was an 80-year-old woman. She had persistent epigastralgia and left back pain. Imaging studies revealed a tumor in the head of the pancreas, which was diagnosed as pancreatic head cancer. We performed subtotal stomach-preserving pancreatoduodenectomy. After the operation, she complained of appetite loss and general fatigue. Her serum sodium levels decreased to 109 mEq/L on postoperative day 11. She was diagnosed with SIADH using the SIADH diagnostic criteria listed by the Japanese Ministry of Health, Labor and Welfare. We treated the patient with sodium supplementation for hyponatremia, and her symptoms ameliorated. After the event, she did not relapse with hyponatremia. This case is significant in that we performed differential diagnosis after major gastrointestinal surgery for pancreatic cancer and diagnosed SIADH at an early stage.

A Systematic Review of Sodium Disorders in HHV-6 Encephalitis

Human herpesvirus 6 (HHV-6) encephalitis has a high mortality rate. Among those who survive, ~80% develop some type of permanent neurologic disorder. Early diagnosis and treatment may help prevent long-term sequelae. There have been several case reports as well as retrospective and prospective studies associating HHV-6 encephalitis with some form of sodium imbalance, either hyponatremia or hypernatremia; however, the exact frequency post-HCT is unknown, with reports ranging from 30% to 100%. We performed a systematic review of the literature and found 34 cases of HHV-6 encephalitis reported in conjunction with sodium imbalance that documented the timing of that imbalance relative to the onset of encephalitis. Sodium imbalance occurred before or at the onset of HHV-6 encephalitis in all but 2 cases (94%). This finding supports previous suggestions that sodium imbalance can be considered an early indicator of the potential development or presence of HHV-6 encephalitis in at-risk patient populations.

Status epilepticus during correction of hyponatremia in a patient with Alzheimer's disease: A case report

An 83-year-old Japanese man with Alzheimer’s disease was admitted to our hospital for treatment of hyponatremia resulting from water intoxication. During hospitalization, the patient developed focal impaired awareness seizures, focal to bilateral tonic-clonic seizures, and subsequent status epilepticus. Electroencephalogram during focal impaired awareness seizures showed rhythmic 5–9 Hz theta activity in the right frontotemporal region. Electroencephalogram during focal to bilateral tonic-clonic seizures showed bilateral polyspikes. Electroencephalogram during an interseizure period revealed sharp waves in the right frontal region. Continuous intravenous administration of midazolam was the only effective treatment for status epilepticus. The patient died of aspiration pneumonia on day 58. Hyponatremia-associated status epilepticus is rare; in the present case, multifocal epileptogenicity resulting from Alzheimer’s disease and hyponatremia-associated elevation of glutamate levels in the synaptic cleft may have contributed to the onset of focal to bilateral tonic-clonic seizures with subsequent status epilepticus.

Clinical practice recommendations for the diagnosis and management of human herpesvirus-6B encephalitis after allogeneic hematopoietic stem cell transplantation: the Japan Society for Hematopoietic Cell Transplantation

Reactivation of human herpesvirus (HHV)-6B is relatively common after allogeneic hematopoietic stem cell transplantation (HSCT) and HHV-6B diseases may consequently develop. Among them, HHV-6B encephalitis is a serious and often fatal complication. The aim of these clinical practice recommendations is to provide diagnostic and therapeutic guidance for HHV-6B encephalitis after allogeneic HSCT. In this evidence-based review, we critically evaluated data from the published literature. The Grading of Recommendations Assessment, Development and Evaluation (GRADE) methodology was used to assist in generating recommendations. We have summarized the findings that contribute to decision-making and we have provided our recommendations. In cases where rigorous clinical data are unavailable, recommendations have been developed in discussions with physicians who have relevant expertize.

Successful Treatment of Syndrome of Inappropriate Antidiuretic Hormone Secretion Associated with Neuro-Sweet Disease in Myelodysplastic Syndrome

Sweet disease may occur in several organs, and central nervous system involvement, known as Neuro-Sweet disease (NSD), is rare. The clinical features of NSD include recurrent encephalomeningitis accompanied by fever and erythematous plaques; systemic corticosteroid therapy is highly effective. Syndrome of inappropriate antidiuretic hormone secretion (SIADH) is an important electrolyte abnormality because it can be life-threatening. We describe the first case of SIADH and NSD associated with low-risk myelodysplastic syndrome that was successfully treated with corticosteroids and cyclosporine. The patient has remained stable for 1 year without any recurrence.

Roseolovirus-associated encephalitis in immunocompetent and immunocompromised individuals

The roseoloviruses, human herpesvirus (HHV)-6A, HHV-6B, and HHV-7, can cause severe encephalitis or encephalopathy. In immunocompetent children, primary HHV-6B infection is occasionally accompanied by diverse clinical forms of encephalitis. Roseolovirus coinfections with heterologous viruses and delayed primary HHV-7 infection in immunocompetent adults result in very severe neurological and generalized symptoms. Recovery from neurological sequelae is slow and sometimes incomplete. In immunocompromised patients with underlying hematological malignancies and transplantation, frequent single or simultaneous reactivation of roseoloviruses elicit severe, lethal organ dysfunctions, including damages in the limbic system, brain stem, and hippocampus. Most cases have been due to HHV-6B with HHV-6A accounting for 2-3%. The most severe manifestation of HHV-6B reactivation is post-transplantation limbic encephalitis. Seizures, cognitive problems, and abnormal EEG are common. Major risk factors for HHV-6B-associated encephalitis include unrelated cord blood cell transplantation and repeated hematopoietic stem cell transplantation. Rare genetic disorders, male gender, certain HLA constellation, and immune tolerance to replicating HHV-6 in persons carrying chromosomally integrated HHV-6 might also predispose an individual to roseolovirus-associated brain damage. At this time, little is known about the risk factors for HHV-7-associated encephalitis. Intrathecal glial cell destruction due to virus replication, overexpression of proinflammatory cytokines, and viral mimicry of chemokines all contribute to brain dysfunction. High virus load in the cerebrospinal fluid, hippocampal astrogliosis, and viral protein expression in HHV-6B-associated cases and multiple microscopic neuronal degeneration in HHV-7-associated cases are typical laboratory findings. Early empirical therapy with ganciclovir or foscarnet might save the life of a patient with roseolovirus-associated encephalitis.

Hyponatremia Associated with Hepatocellular Carcinoma

Hyponatremia is the most common electrolyte abnormality in clinical practice, and a differential diagnosis of the etiologic disorders is crucial because hyponatremia is associated with many different disease states including malignancies. Although only a few cases of hyponatremia with hepatocellular carcinoma (HCC) have been previously reported, the abnormal expression of arginine vasopressin (AVP) in tumor cells has not been demonstrated. We herein present a rare case of hyponatremia associated with the aberrant expression of AVP in tumor cells of HCC. This case suggests that an extensive diagnostic work-up is needed in patients with hyponatremia because hyponatremia may provide diagnostic clues for the presence of other underlying disorders.

Cerebral salt-wasting syndrome after hematopoietic stem cell transplantation in adolescents: 3 case reports

Cerebral salt-wasting syndrome (CSWS) is a rare disease characterized by a extracellular volume depletion and hyponatremia induced by marked natriuresis. It is mainly reported in patients who experience a central nervous system insult, such as cerebral hemorrhage or encephalitis. The syndrome of inappropriate antidiuretic hormone secretion is a main cause of severe hyponatremia after hematopoietic stem cell transplantation, whereas CSWS is rarely reported. We report 3 patients with childhood acute leukemia who developed CSWS with central nervous system complication after hematopoietic stem cell transplantation. The diagnosis of CSW was made on the basis of severe hyponatremia accompanied by increased urine output with clinical signs of dehydration. All patients showed elevated natriuretic peptide and normal antidiuretic hormone. Aggressive water and sodium replacement treatment was instituted in all 3 patients and 2 of them were effectively recovered, the other one was required to add fludrocortisone administration.

Human herpesvirus 6 is associated with status epilepticus and hyponatremia after umbilical cord blood transplantation

This article describes a case involving a 65-year-old man who experienced nonconvulsive status epilepticus after undergoing an allogenic hematopoietic cell transplantation to treat chronic lymphocytic leukemia. The authors describe the diagnostic work-up and treatment of human herpesvirus 6 infection, and discuss other potential causes of nonconvulsive status epilepticus in similar scenarios.

Status epilepticus after allogeneic hematopoietic cell transplantation (alloHCT) is rare. The authors report a case involving a 65-year-old man with nonconvulsive status epilepticus 34 days after umbilical cord blood transplantion for chronic lymphocytic leukemia. Cerebrospinal fluid and serum were positive for human herpesvirus 6 (HHV6). Magnetic resonance imaging of the brain showed symmetric T2 hyper-intensity bilaterally in the mesial temporal lobes, and T2 hyperintensi-ties and restricted diffusion of bilateral putamina. Despite aggressive anticonvulsive therapy, his seizures only abated with initiation of ganciclovir therapy. The patient completed six weeks of combination antiviral therapy (ganciclovir and foscarnet). His cognitive function gradually improved and, after prolonged rehabilitation, the patient was discharged home with residual intermittent memory loss but otherwise functional. HHV6 should be considered in the differential diagnosis of nonconvulsive status epilepticus after alloHCT, especially in patients with hyponatremia. Empirical antiviral therapy targeting HHV6 should be administered to these patients.