Gastric absorption of D-xylose in the rat: its influence on the D-xylose absorption test

Relatively high incidences of false-positive results of D-xylose absorption tests have been reported. Delayed gastric emptying is invariably listed as one important cause for such tests. However, this conclusion assumes that gastric absorption from the relatively concentrated D-xylose solutions used clinically is negligible. In our study, D-xylose was injected (0.5 gm/kg) into either the stomach or duodenum of rats that had undergone pyloric ligation. Blood xylose levels 30 minutes later were almost as high after intragastric administration (0.61 +/- 0.22 mmol/L) as they were after intraduodenal injection (0.65 +/- 0.16 mmol/L). A chymotrypsin-labile peptide (N-benzoyl-L-tyrosyl-p-aminobenzoate), given at the same time, was poorly absorbed from the stomach, as shown by the low plasma p-aminobenzoic acid levels (14 +/- 2 mumol/L vs. 158 +/- 22 mumol/L after intraduodenal injection). Intragastric absorption of xylose, therefore, did not appear to result from the surgical trauma of pyloric ligation. In rats given doses orally of the D-xylose, the peptide, and a nonabsorbable marker (phenol red), epinephrine and atropine both showed gastric emptying without any surgical trauma, decreased digestion and absorption of the peptide as expected, but did not significantly decrease xylose absorption. These results indicate that, at least in rats, D-xylose is absorbed from relatively concentrated solutions within the stomach. Consequently, circumstances that delay gastric emptying should not markedly decrease xylose absorption. Bacterial overgrowth and altered blood flow seem more likely causes for false-positive D-xylose absorption test results.     

D-xylose absorption and disposition in patients with moderately impaired renal function

D-Xylose kinetics were studied after oral and intravenous administration to 10 patients with impaired renal function, three of whom were being evaluated for intestinal malabsorption. The 0.32 +/- 0.06 L/kg (mean +/- SD) distribution volume of D-xylose in patients with uncomplicated renal impairment was larger than the value of 0.23 +/- 0.04 L/kg that we reported previously for normal subjects (P less than 0.01). Renal clearance was also reduced, averaging 87% of glomerular filtration rate estimated from creatinine clearance, so that the elimination-phase half-life was prolonged to 138 +/- 39 minutes from 75 +/- 11 minutes in normal individuals (P less than 0.01). The 25 gm oral D-xylose dose was 77.4% +/- 14.8% absorbed in the patients with uncomplicated renal impairment, similar to the 69.4% +/- 13.6% absorption reported in normal individuals. However, the absorption half-life was prolonged from 31 +/- 12 minutes in normal subjects to a value of 62 +/- 23 minutes (P less than 0.02). Of the usual clinical indexes of D-xylose absorption, the serum concentration measured 1 hour after the oral dose was best correlated with the extent of D-xylose absorption (r = 0.76; P less than 0.01), and the standard lower normal limit of 0.2 mg/ml was satisfactory.     

Kinetics of D-xylose absorption in patients with human immunodeficiency virus enteropathy

D-Xylose absorption was studied in 12 patients with acquired immunodeficiency syndrome (AIDS) or advanced AIDS-related complex who had had diarrhea for more than 8 weeks, averaged an 11% (range, 3% to 21%) body weight loss during the previous 6 months, and had had negative stool examinations for enteric pathogens. Patients were evaluated by duodenal aspiration and biopsy and received both 25 gm oral and 10 gm intravenous doses of D-xylose. Kinetic analysis of D-xylose absorption was characterized by an absorption rate constant (ka) and a rate constant (ko) reflecting nonabsorptive loss. Extent of D-xylose absorption averaged 18.4% +/- 9.3% (+/- SD) in the 12 patients (normal greater than 60%). Percentage of weight loss during the previous 6 months was negatively correlated with ka (r = -0.69; p = 0.018) in the 11 patients in whom this parameter was reduced but was not correlated with either ko or extent of D-xylose absorption. In these patients with human immunodeficiency virus enteropathy, ka was reduced out of proportion to the minor histologic changes present in the duodenal biopsy specimens.     

Influence of the menstrual cycle on the absorption and elimination of D-xylose

Thirteen healthy female volunteers with regular menstrual cycles (28 +/- 2 days) received 25 gm oral and 5 gm intravenous doses of D-xylose on 2 successive days during the follicular, ovulatory, and luteal phases of two consecutive menstrual cycles. The ovulation time was characterized by luteinizing hormone levels, body basal temperatures, and progesterone and estradiol serum levels. D-Xylose was assayed in plasma and urine with a phloroglucinol-based colorimetric method. The findings of this study indicated that menstrual cycle did not significantly affect D-xylose absorption. After oral administration, the total clearance was significantly increased in cycle 2 during the luteal phase (p = 0.004). After intravenous administration in both cycles, D-xylose total clearance was also significantly faster during the luteal phase (p = 0.038 and p = 0.041, respectively). After oral administration, the renal clearance tended to be higher during the luteal phase in both cycles studied. After intravenous administration, this parameter was increased during the luteal phase by 24% and 25% in cycle 1 and by 8% and 12% in cycle 2. These findings are consistent with those of others showing an increase in glomerular filtration rate (GFR) during the luteal phase of the menstrual cycle. The findings of this study seem to be explained by the hormonal changes occurring during the menstrual cycle. Further investigations are warranted with use of specific probes of renal processes (GFR, renal reabsorption and tubular secretion) to confirm our findings and to elucidate the underlying mechanisms.     

A modified thymol turbidity test in hyperglobulinaemia

The chemical basis of the thymol turbidity test has been further investigated by the use of various purified human serum proteins and of six new reagents having pH values of 4, 7 and 9, three with and three without thymol, all at ionic strength 0.01. IgM was the only protein to give turbidity alone, but some IgG preparations gave turbidities in combination with lipoproteins. Turbidity was usually maximal at pH 7. IgM turbidity was usually increased by IgG and by lipoproteins at pH 7. Albumin and seromucoid had little effect on turbidities produced by other proteins.Results are given with sera from IgA myelomatosis (24 cases), IgG myelomatosis (35), Waldenstrom's macroglobulinaemia (29), polyclonal hyperglobulinaemia (60) and normal subjects (41). No simple test was found for differentiating these conditions completely, although some combinations of tests were much more frequently seen in IgA myelomas and in macroglobulinaemia than in the polyclonal group. There was no difference between L and K subtypes of myeloma or macroglobulinaemia. The 7T reagent (a buffered solution of thymol at pH 7 and ionic strength 0.01) is recommended as a screening test for hyperglobulinaemia.     

A modified capillary test using 4% ficin

A capillary technique is described for economical Rh-phenotyping of large numbers of blood samples using diluted antisera and 4% ficin solution. This system is no more time consuming that conventional tube techniques, since enzyme premodification of the cells is not required.     

微量快速测定木糖法检测创伤后肠道吸收功能的实验研究(英文)

目的寻找简单、快捷、精确、稳定和微量的检测肠道吸收功能的方法,以作判断严重创伤后肠道吸收功能的诊断指标。方法以Eberts等建立的方法作适当调整,使之微量和动态测定小动物血和尿中木糖的含量。反复作5次标准曲线,测定Wistar大鼠空腹血和6只口服0.5g/kg木糖(D-xylose)后大鼠2和4h血的含量,并测定7只肠缺血再灌注大鼠血木糖含量。结果经DU-7Backman扫描证实最大吸收峰在554nm,以5次0～4mmol/L范围内测定木糖标准曲线呈良好的线性关系(r=0.9979±0.0017);大鼠口服木糖后2h血含量(154±6)mg/L;4h后降至(87±11)mg/L。缺血再灌注后2和4h血含量分别为162±5和(80±8)mg/L,较正常大鼠2h吸收快。取大鼠口服2和4h血浆批内重复6次,批间重复6次,结果批内变异系数为1.98%,批间变异系数为3.10%;各标准木糖回收率为97.2%～104.3%。结论微量快速测定木糖方法简单、快捷、稳定,可用作判断严重创伤后肠道吸收功能损伤的指标。     

A modified indirect fluorescent antibody test for the diagnosis of brucellosis

We adapted the conventional indirect fluorescent antibody (IFA) test to assay IgM and IgG Brucella-specific antibodies to differentiate acute from chronic infections rather than measure total antihuman globulin specific antibodies. The results were compared with the slide agglutination test (SAT) used for screening and the quantitative microagglutination test (MAT). Of a total of 118 randomly selected samples sent for anti-Brucella antibodies received at a general hospital laboratory, 58 (47.9%) were found to be positive for IFA-IgG test but not necessarily by other tests. Eleven of these cases were positive for Brucella melitensis by culture. Sixty serum samples found negative for Brucella antibodies by IFA and other tests were of patients with medical conditions other than brucellosis. Fifty serum samples from healthy blood donors were negative for Brucella spp. antibodies by all the three tests. The IFA test was found to be a more sensitive test than MAT and distinguished an acute infection from chronic disease.