The effect of storage time and freeze-thaw cycles on the stability of serum samples

Introduction: Optimal storage of serum specimens in central laboratories for a long period for multicenter reference interval studies, or epidemiologic studies remains to be determined. We aimed to examine the analytical stability of chemistry analytes following numerous freeze-thaw and long term storage. Materials and methods: Serum samples were obtained from 15 patients. Following baseline measurement, sera of each subject were aliquoted and stored at -20 ˚C for two experiments. A group of sera were kept frozen for up to 1, 2 and 3 months and then analyzed for stability. The other experiment consisted of one to ten times of freeze and thaw cycles. Total of 17 chemistry analytes were assayed at each time point. The results were compared with those obtained from the initial analysis of fresh samples. Median or mean changes from baseline (T0) concentrations were evaluated both statistically and clinically according to the desirable bias. Results: Of the analytes studied, aspartate aminotransferase (AST), alanine aminotransferase (ALT), creatine kinase (CK), gamma-glutamyl transferase (GGT), direct bilirubin, glucose, creatinine, cholesterol, triglycerides, high density lipoprotein (HDL) were stable in all conditions. Blood urea nitrogen (BUN), uric acid, total protein, albumin, total bilirubin, calcium, lactate dehydrogenase (LD) were changed significantly (P < 0.005). Conclusions: As a result, common clinical chemistry analytes, with considering the variability of unstable analytes, showed adequote stability after 3 months of storage in sera at -20 °C, or up to ten times of freeze-thaw cycle. All the same, such analysis can only be performed for exceptional cases, and this should be taken into account while planning studies

Erectile dysfunction prevalence and sexual function status in patients with chronic obstructive pulmonary disease

Purpose: We determined sexual status and erectile dysfunction (ED) in outpatients with chronic obstructive pulmonary disease (COPD)

A Systematic Study on the Synthesis of n-Butyl Substituted 8-Aminoquinolines

A systematic study on the synthesis of 8-aminoquinoline derivatives with an n-butyl group at each alternate position of the quinoline ring was carried out. Skraup Reaction and its Doebner-von Miller variation were used to obtain most of the quinoline ring except for the 2-butyl-8-aminoquinolines and 4-butyl-8-aminoquinolines where the commercially available methylquinoline derivatives were used as precursors. The structures of the synthesized compounds were characterized by FTIR, H-1-NMR, COSY, C-13-NMR and HRMS spectra

Conjunctival dichlorvos poisoning

WOS: 000240407200190

Nocturnal polyuria in patients with lower urinary tract symptoms and response to alpha-blocker therapy

Objectives. To determine the prevalence of nocturnal polyuria (NP, defined as a nocturnal urine fraction exceeding one third of the daily urine output in elderly men) in patients with lower urinary tract symptoms (LUTS) suggestive of benign prostatic hyperplasia (BPH) and clinical responsiveness to alpha-blocker therapy

Stability studies of common biochemical analytes in serum separator tubes with or without gel barrier subjected to various storage conditions

Introduction: The collected and shipped blood samples are exposed to a various extra-analytical factors prior to analysis. The aim of the study was to determine the stability of analytes in serum gel tubes and plain tubes exposed to a range of storage temperatures and times after centrifugation. Materials and methods: Fifteen healthy volunteers were recruited and venous blood was collected into four tubes, two with and two without gel separator. Analyzing the baseline samples in 30 min, all were stored at 4ºC or 24ºC for 6, 12, 18, 24, 30, 36, 48 and 72 hours and 1 week. Sixteen biochemi-cal anaytes were measured on each sample. Variations remained under the desirable bias conside-red as clinically insignificant. Results: On day three, most analytes remained stable including albumin, protein, creatinine, choles-terol, triglycerides, gamma-glutamyl transferase (GGT), alkaline phosphatase (ALP), alanine aminot-ransferase (ALT), creatine kinase (CK), lactate dehydrogenase (LD) regardless of tube types. Gluco-se concentration decreased markedly (P = 0.001) beginning from the first hours of storage in plain serum. The stability maximized for the analytes including glucose, total bilirubin, urea nitrogen (BUN), uric acid stored at 4 ºC in gel tubes. Aspartate aminotransferase (AST) activity increased significantly (P = 0.002) up to 48-h, however bias was not significant clinically. High density lipoprotein (HDL) con-centration was stable in gel tubes at 24 ºC, in plain tubes at 4 ºC stored up to 36-h. Conclusion: Serum gel or non-gel tubes might be used interchangeably for 11 analytes chilled or at 24 ºC, whereas some restrictions must be applied for glucose, AST, BUN, HDL, and uric acid

Relation between acute urinary retention, chronic prostatic inflammation and accompanying elevated prostate-specific antigen

Objective. To determine if there is a relationship between acute urinary retention ( AUR), the prostate- specific antigen ( PSA) level and chronic inflammation of the prostate. We therefore studied patients with benign prostatic obstruction ( BPO) with ( n = 64) or without ( n = 168) acute urinary retention ( AUR) who underwent transurethral resection of the prostate ( TURP) in a retrospective case control study