Creatinine ; Humans ; Male ; Meals ; Methods ; Nitrogen ; Osmolar Concentration ; Potassium ; Sodium ; Sodium, Dietary ; Specific Gravity ; Urea ; Urine Specimen Collection

The kidney collecting duct (CD) is a tubular segment of the kidney where the osmolality and final flow rate of urine are established, enabling urine concentration and body water homeostasis. Water reabsorption in the CD depends on the action of arginine vasopressin (AVP) and a transepithelial osmotic gradient between the luminal fluid and surrounding interstitium. AVP induces transcellular water reabsorption across CD principal cells through associated signaling pathways after binding to arginine vasopressin receptor 2 (AVPR2). This signaling cascade regulates the water channel protein aquaporin-2 (AQP2). AQP2 is exclusively localized in kidney connecting tubules and CDs. Specifically, AVP stimulates the intracellular translocation of AQP2-containing vesicles to the apical plasma membrane, increasing the osmotic water permeability of CD cells. Moreover, AVP induces transcription of the Aqp2 gene, increasing AQP2 protein abundance. This review provides new insights into the transcriptional regulation of the Aqp2 gene in the kidney CD with an overview of AVP and AQP2. It summarizes current therapeutic approaches for X-linked nephrogenic diabetes insipidus caused by AVPR2 gene mutations.
Aquaporin 2 ; Arginine Vasopressin ; Body Water ; Cell Membrane ; Diabetes Insipidus, Nephrogenic ; Gene Expression Regulation ; Homeostasis ; Kidney ; Kidney Tubules, Collecting ; Osmolar Concentration ; Permeability ; Phenobarbital ; Receptors, Vasopressin ; Water

PURPOSE: To evaluate tear film function in patients with diabetes mellitus (DM) using tear film osmolarity (TFO) measurements compared to other tear film function tests. METHODS: DM patients without any history of ocular surface disorder but with potential effects on the tear film were enrolled in this cross-sectional study. Data including dry eye symptoms, duration of DM, stage of diabetic retinopathy and blood hemoglobin A1c levels were recorded. Tear film break-up time (TBUT) and basic tear secretion (Schirmer test) were assessed. TFO was determined using the Tearlab Osmolarity System. The outcome measures were the difference between the mean values of TBUT, basic tear secretion and TFO in both the study and control groups. RESULTS: We recruited 51 DM patients and 20 control subjects with a mean age of 51.2 (range, 21 to 70) and 48.5 (range, 24 to 70) years, respectively. A total of 27 patients (53%) and 11 controls (55%) reported dry eye symptoms (p = 0.668). The mean TBUT was 10.2 ± 4.8 seconds in the study group versus 10.5 ± 2.8 seconds in controls, which was not significantly different (p = 0.747). The mean Schirmer test score was 8.1 ± 4.3 mm in the patients versus 10.1 ± 3.0 mm in the controls (p = 0.069). The mean TFO was 294.1 ± 12.9 mosmol/L in the patients versus 291.4 ± 14.5 mosmol/L in the controls (p = 0.456). It was significantly higher in patients with poor glycemic control determined by hemoglobin A1c > 8% (p = 0.003). TFO had a positive correlation with the duration of DM (p = 0.030) but not with the stage of diabetic retinopathy (p = 0.944). However, TFO showed a significant relationship with dry eye symptoms (p = 0.001). CONCLUSIONS: TFO is impaired in patients with uncontrolled DM and is better correlated with glycemic control and dry eye symptoms than the TBUT and Schirmer tests.
Cross-Sectional Studies ; Diabetes Mellitus ; Diabetic Retinopathy ; Humans ; Osmolar Concentration ; Outcome Assessment (Health Care) ; Tears

PURPOSE: To evaluate the protective effect of applying an ophthalmic viscosurgical device (OVD) to the ocular surface during cataract surgery and its ability to prevent dry eye syndrome. METHODS: Twenty-four patients aged 50 to 75 years who underwent cataract surgery at Seoul National University Bundang Hospital and agreed to participate in the study were included and divided into two groups: a study group who underwent cataract surgery after application of an OVD to the ocular surface, and a control group who underwent cataract surgery without application of an OVD. DisCoVisc was used as the OVD in the study group, while other factors including surgical techniques and administration of anesthetic agents were performed in both groups in the same manner. Indicators of dry eye syndrome including ocular staining score, tear break-up time, and tear osmolality were analyzed. Ocular surface disease index and a visual analog scale were analyzed for dry eye symptoms, and the amount of balanced salt solution used during surface irrigation and operation time were also analyzed. RESULTS: Significant improvement in the tear break-up time, corneal ocular staining score, and ocular surface disease index score in the study group compared with the control group one week after operation (by the Mann-Whitney test). Use of OVD was associated with longer operating time. CONCLUSIONS: OVD applied to the ocular surface during cataract surgery had a protective effect on the ocular surface one week after surgery.
Anesthetics ; Cataract Extraction ; Cataract ; Dry Eye Syndromes ; Humans ; Osmolar Concentration ; Seoul ; Tears ; Visual Analog Scale

Adipsic hypernatremia is a rare disease where patients do not feel thirst even in the increased serum osmotic pressure and results in electrolyte imbalance, severely increased osmotic pressure and neurologic symptoms like nausea, vomiting, and seizures. We report a 12-year-old male patient who had underwent a trans-sphenoidal surgery for craniopharyngioma newly diagnosed with adipsic hypernatremia after having growth hormone replacement for growth hormone deficiency. The patient visited emergency room complaining of generalized weakness, tremor in both legs, and poor oral intake including water after starting growth hormone replacement therapy. Laboratory test revealed serum sodium 168 mmol/L and serum osmolality 329 mOsm/kg, despite the patient didn't feel any thirst at all. We treated him with scheduled water intake of 2.5 L a day with intranasal vasopressin. He admitted to Soonchunhyang University Gumi Hospital and Soonchunhyang University Seoul Hospital for 4 times during the following 8 months and serum sodium level and osmolality was controlled by scheduled water intake combined with intranasal vasopressin treatment. It is still unclear whether growth hormone replacement worked as a trigger of hypernatremia.
Child ; Craniopharyngioma ; Drinking ; Emergency Service, Hospital ; Growth Hormone ; Gyeongsangbuk-do ; Humans ; Hypernatremia ; Leg ; Male ; Nausea ; Neurologic Manifestations ; Osmolar Concentration ; Osmotic Pressure ; Rare Diseases ; Seizures ; Seoul ; Sodium ; Thirst ; Tremor ; Vasopressins ; Vomiting ; Water

PURPOSE: To evaluate the efficacy of 3% diquafosol tetrasodium (DQ) after laser-assisted in-situ keratomileusis (LASIK). METHODS: This prospective randomized study included 150 eyes in 75 patients who were scheduled for LASIK. The patients in the 3% diquafosol tetrasodium (DQ) group (37 patients, 74 eyes) were instructed to apply one drop of DQ, six times daily post-op, while the patients in the 0.3% sodium hyaluronate (HA) group (38 patients, 76 eyes) were instructed to apply one drop of HA, six times daily post-op. A Schirmer test, tear film break-up time (BUT), corneal and conjunctival fluorescein staining score (FLSS), and ocular surface disease index (OSDI) were evaluated pre-op and at 1, 4, and 12 weeks post-op while the tear osmolarity was evaluated pre-op and at 4 and 12 weeks post-op. RESULTS: There was no significant difference between the two groups regarding Schirmer test results or tear osmolarity and conjunctival FLSS. The BUT was significantly higher in the DQ group at 1 week and 12 weeks post-op. The corneal FLSS was significantly lower in the DQ group at 1 week, 4 weeks and 12 weeks post-op. The OSDI was significantly lower in the DQ group at 1 week post-op. CONCLUSIONS: Use of 3% diquafosol tetrasodium after surgery improved ocular dryness and increased the tear film stability.
Fluorescein ; Humans ; Hyaluronic Acid ; Keratomileusis, Laser In Situ ; Osmolar Concentration ; Prospective Studies ; Tears

In the brain, a reduction in extracellular osmolality causes water-influx and swelling, which subsequently triggers Cl⁻- and osmolytes-efflux via volume-regulated anion channel (VRAC). Although LRRC8 family has been recently proposed as the pore-forming VRAC which is activated by low cytoplasmic ionic strength but not by swelling, the molecular identity of the pore-forming swelling-dependent VRAC (VRAC(swell)) remains unclear. Here we identify and characterize Tweety-homologs (TTYH1, TTYH2, TTYH3) as the major VRAC(swell) in astrocytes. Gene-silencing of all Ttyh1/2/3 eliminated hypo-osmotic-solution-induced Cl⁻ conductance (I(Cl,swell)) in cultured and hippocampal astrocytes. When heterologously expressed in HEK293T or CHO-K1 cells, each TTYH isoform showed a significant I(Cl,swell) with similar aquaporin-4 dependency, pharmacological properties and glutamate permeability as I(Cl,swell) observed in native astrocytes. Mutagenesis-based structure-activity analysis revealed that positively charged arginine residue at 165 in TTYH1 and 164 in TTYH2 is critical for the formation of the channel-pore. Our results demonstrate that TTYH family confers the bona fide VRAC(swell) in the brain.
Arginine ; Astrocytes ; Brain ; Cytoplasm ; Glutamic Acid ; Humans ; Osmolar Concentration ; Permeability

Dry eye syndrome is a multifactorial disease of the ocular surface characterized by a loss of homeostasis of the tear film, and accompanied by ocular symptoms. Tear film instability and hyperosmolarity, ocular surface inflammation and damage, and neurosensory abnormalities play etiological roles. Symptom screening with the Five-item Dry Eye Questionnaire or Ocular Surface Disease Index can be used to identify the possibility that a patient might have DED dry eye syndrome and triggers. The results of these screening tools can lead to performing diagnostic tests of (ideally non-invasive) breakup time, osmolarity and ocular surface staining with fluorescein and lissamine green (observing the cornea, conjunctiva and eyelid margin). Meibomian gland dysfunction, lipid thickness/dynamics and assessments of the volume and severity of tear allow the subclassification of dry eye syndrome as predominantly evaporative or aqueous deficient, which informs the management of dry eye syndrome. A staged management algorithm was derived that presents a stepwise approach to implementing the various management and therapeutic options according to disease severity.
Conjunctiva ; Cornea ; Diagnosis ; Diagnostic Tests, Routine ; Dry Eye Syndromes ; Eyelids ; Fluorescein ; Homeostasis ; Humans ; Inflammation ; Mass Screening ; Meibomian Glands ; Osmolar Concentration ; Tears

A 22-year-old male patient was diagnosed with autosomal dominant polycystic kidney disease (ADPKD). He received conservative treatment with an angiotensin-converting enzyme inhibitor. Two years later, oral therapy, consisting of 60 mg tolvaptan per day, was initiated. Compared with height-adjusted total kidney volume, the rate of kidney growth reduced significantly from 7.33% to 0.66% annually, since commencement of the tolvaptan therapy. The liver enzyme profile and serum sodium level and osmolality were constantly within normal ranges. In Korea, this is the first reported case of a patient with ADPKD who received tolvaptan treatment for more than 1 year. This case demonstrates that long-term tolvaptan treatment appears to be safe, well tolerated, and effective for ADPKD.
Humans ; Kidney ; Korea ; Liver ; Male ; Osmolar Concentration ; Polycystic Kidney, Autosomal Dominant ; Reference Values ; Sodium ; Young Adult

Hyponatremia is defined as a plasma sodium concentration of < 135 mEq/L. It is a common electrolyte imbalance in newborns. We report the case of a term neonate with cleft lip, cleft palate, imperforate anus, normal male karyotype, and chronic hyponatremia. On the 4th day of life, he showed hyponatremia (plasma sodium concentration 130 mEq/L) with low serum osmolality (275 mOsm/kg), high urine sodium (116.7 mEq/L), and high urine osmolality (412 mOsm/kg). His thyroid and adrenal functions were normal. Despite intravenous and oral sodium supplementation and hydrocortisone treatment, hyponatremia persisted. Brain magnetic resonance imaging showed normal results. He was diagnosed as having reset osmostat, a rare subtype of the syndrome of inappropriate secretion of antidiuretic hormone characterized by a subnormal threshold for antidiuretic hormone secretion, with hypotonic hyponatremia.
Anus, Imperforate* ; Brain ; Cleft Lip* ; Cleft Palate* ; Humans ; Hydrocortisone ; Hyponatremia* ; Inappropriate ADH Syndrome ; Infant, Newborn* ; Karyotype ; Magnetic Resonance Imaging ; Male ; Osmolar Concentration ; Plasma ; Sodium ; Thyroid Gland