Biomedical subjects
Publications and source records attributed to G T Sanders.
A 32-year-old woman delivered a normal male infant by the vertex 14 years after hemipelvectomy. During pregnancy she remained ambulatory with forearm crutches and wore a specially designed sling that she felt provided support and comfort. It is suggested that such external support to the uterus of the pregnant woman after hemipelvectomy may enhance presentation by the vertex.
Polystyrene tubes were coated with IgG, isolated from antiserum against human prostatic acid phosphatase, and incubated with a known amount of purified antigen as a standard, and sera from patients. The amount of bound prostatic acid phosphatase was established by using its enzyme activity. This was performed either spectrophotometrically with p-nitrophenylphosphate (enzyme immunoassay) or fluorometrically with alpha-naphthylphosphate as a substrate (immunofluorescence assay). Results of both methods were compared with those of the conventional method and were evaluated in four groups of patients with: non-prostatic disease, hypertrophy, treated and untreated prostatic carcinoma. The first group was used to establish the upper limit of normal. In the hypertrophy group, the specificity of the immunological methods when compared with the conventional method, improved from 79% to 91%. Sensitivity, calculated from the untreated prostatic carcinoma group, was 74% for the enzyme immunoassay (EIA) and 71% for the immunofluorescence assay (IFA). The probability of having either carcinoma or hypertrophy, given observed EIA or IFA values, was calculated by the statistical method of the logistic regression.
Hemodialysis with a polyacrylonitril membrane is evaluated as a possible method to alleviate pruritus accompanying severe prolonged cholestasis. To that extent results of a series of 30 dialysis sessions of a patient with advanced primary biliary cirrhosis are reported. Efficacy is measured with a pruritus score, kept by the patient herself, as well as with pre- and postdialysis plasma bile acid concentrations and bile acid concentrations in dialysates. Bile acid removal can then be calculated in three different ways: (a) From the decrease of the plasma bile acid concentration by dialysis a figure of 300 mumol bile acid removed is estimated. (b) Measurements of bile acid concentration in the dialysates results in a figure of 666 +/- (SD) 87 mumol bile acid removed. (c) From the mean pre- and postdialysis plasma bile acid concentrations together with an effective clearance rate of 8 ml/min for the bile acid mixture, calculated from ultrafiltration experiments, a removal of 589 +/- 100 mumol bile acid is calculated. These figures compare favorably with figures reported in the literature for the alternative techniques used, plasmapheresis and plasma perfusion over activated charcoal.
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Lundh test and PABA test results were compared in 50 patients. In the resulting correlation curve three areas of interest were differentiated: (1) an area with mean tryptic activity, found in the Lundh test, below 4 U/ml, where an abnormal PABA test result was also seen; (2) an intermediate area from 4 to 9 U/ml, where PABA test results may be found in discordance with the Lundh test; (3) the normal level, where PABA excretion was shown to be independent of intestinal chymotrypsin activity. In experiments in vitro on the kinetics of the hydrolysis of BTPABA by chymotrypsin the profound influence of the pH on Km and Vmax was shown. This influence of the pH explains why in the intermediate area of pancreatic dysfunction normal PABA test results were found in a number of cases. A higher mean pH level of the Lundh test aspirates was found for patients with a normal PABA test result than for patients with an abnormal PABA test.
A fast electrophoretic method for measuring glycosylated haemoglobin (HbA1) is described. Eight samples per cell can be assayed in a single run. Results are compatible with those found by macro-column cation-exchange chromatography; precision is good. The practical short-comings of the commercially ready-made mini-column chromatographic procedures are not seen using this method.
We studied the influence of many variables on the cation-exchange chromatographic determination of glycohemoglobin was minicolumns (HbA1) and with macrocolumns (HbA1a+b and HbA1c). Minicolumns are most sensitive to buffer composition. The best conditions are pH 6.78 and sodium, potassium, and phosphate concentrations of 54.8, and 36 mmol/L, respectively. In fact, there is no clear cut-off point for elution. A cyanide concentration of 1.5 mmol/L has no negative effects. For macrocolumns, the influence of temperature is demonstrated; 20 degrees C is optimal. A higher temperature caused results for HbA1 to be higher. For minicolumns, the temperature effect corresponds to 1% HbA1 per 1 degrees C, necessitating rigorous temperature control. The amount of sample applied also influences the results. Therefore a constant column load, chosen between 1.3 and 2.0 mg of Hb permilliliter of resin, is advised. Heparinized blood can be kept for three days at 4 degrees C; hemolyzed samples are best stored at -70 degrees C.
A reliable method for the determination of uric acid in plasma or serum is described. The hydrogen peroxidase developed in the uricase reaction is used, together with peroxidase, for the coupling of sulphonated dichlorophenol and 4-aminoantipyine to a red dye. The difference in absorbance at 515 nm before and after addition of uricase is measured. Of the components tested for interference some gave rise to falsely lowered values. Reagents are cheap and the high molecular absorption coefficient of the red dye permits the use of small sample volumes.
Demonstration of prostate-specific acid phosphatase by immunologic methods in tissue sections or in plasma necessitates a monospecific antiserum. This is produced by immunizing rabbits with pure prostate-specific acid phosphatase antigen, prepared from seminal fluid. The ejaculate is centrifuged, dialyzed against a citrate buffer, pH 4.8, and centrifuged again. The supernatant is brought onto a Sephacryl S-200 Superfine column and eluted with the same buffer. Prostate-specific acid phosphatase-positive fractions are concentrated, brought onto and stepwise eluted from a Sulphopropyl Sephadex column with citrate buffers at pH 4.8, 5.2, and 5.5. Fractions containing prostate-specific acid phosphatase are concentrated again and purified over a Blue Sepharose CL-6 B column. After elution, a new concentration step yields a protein concentration of 0.5-1.0 mg . ml-1. This sample in polyacrylamide gel electrophoresis shows a single protein band and is used to immunize female rabbits. The purity of the antiserum is then tested by immunoelectrophoresis and an Ouchterlony technic. Besides anti-prostate-specific acid phosphatase, two other antibodies against serum proteins are present, one of which is anti-albumin. Absorption of these impurities results in a monospecific antiserum against prostate-specific acid phosphatase.
This study advocates cautious use of the kinetic determination method for acid phosphatase with alpha-naphthylphosphate as substrate and a diazonium salt for colour development. The occurrence of considerable blank rates due to the spontaneous hydrolysis of the substrate was noticed. Of the diazonium salts which were tested as alternatives for Fast Red TR, diazotised p-nitroaniline seemed to be useful. Also the interaction between plasma components and diazonium salts may influence the results of the determination. In this respect a number of possible interfering compounds was investigated and from these a structural element which may lead to side reactions was deduced.
An indirect immunohistochemical technique is described for identification of the prostatic origin of metastases in formalin fixed, paraffin or paraplast embedded material. A rabbit antiserum against the prostate specific acid phosphatase isoenzyme was developed. The method is applicable with or without previous decalcification. In 30 cases of prostatic carcinoma there was only one negative result, and in 20 cases of metastases from prostatic carcinoma positive results were obtained in every instance. All carcinomas (primary focus or metastasis) of non prostatic origin (55) stained negatively with the developed antiserum. The application and possible limitations of the method are discussed.
In ten ileostomy patients, a 14C-cholylglycine breath test was performed. The 14CO2 in the exhaled air and the 14C bile acid quantity and composition and fat content in the subsequent 24 h ileostomy effluent were determined and compared to the values in twenty healthy controls. The results show that in ileostomy patients only minor bile acid-deconjugation occurs in vivo. Deconjugation in the ileostomy bags was found to be mainly responsible for the absence of conjugated bile acids in many of the ileostomy effluent samples. Secondary bile acids were not present in these patients, as determined by TLC. The fecal fat and bile acid excretion was found to be in the normal range in ileostomy patients provided no concomitant ileum resection was present.
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Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
This review deals with the six main clinical situations related to magnesium or one of its fractions, including ionized magnesium: renal disease, hypertension, pre-eclampsia, diabetes mellitus, cardiac disease, and the administration of therapeutic drugs. Issues addressed are the physiological role of magnesium, eventual changes in its levels, and how these best can be monitored. In renal disease mostly moderate hypermagnesemia is seen; measuring ionized magnesium offers minimal advantage. In hypertension magnesium might be lowered but its measurement does not seem relevant. In the prediction of severe pre-eclampsia, elevated ionized magnesium concentration may play a role, but no unequivocal picture emerges. Low magnesium in blood may be cause for, or consequence of, diabetes mellitus. No special fraction clearly indicates magnesium deficiency leading to insulin resistance. Cardiac diseases are related to diminished magnesium levels. During myocardial infarction, serum magnesium drops. Total magnesium concentration in cardiac cells can be predicted from levels in sublingual or skeletal muscle cells. Most therapeutic drugs (diuretics, chemotherapeutics, immunosuppressive agents, antibiotics) cause hypomagnesemia due to increased urinary loss. It is concluded that most of the clinical situations studied show hypomagnesemia due to renal loss, with exception of renal disease. Keeping in mind that only 1% of the total body magnesium pool is extracellular, no simple measurement of the real intracellular situation has emerged; measuring ionized magnesium in serum has little added value at present.