Specific affinity-chromatographic measurement of glycated hemoglobins in uremic patients

The clinical utility of glycated hemoglobin measurements in renal failure is controversial, given numerous earlier studies showing no correlation between glycated hemoglobin and other indicators of blood glucose control in uremic subjects. This problem is attributable, in part, to analytical interferences from carbamylated hemoglobins. We report use of a specific affinity method to measure glycated hemoglobins in a group of uremic patients, diabetic and nondiabetic, undergoing treatment by continuous ambulatory peritoneal dialysis. Concentrations of glycated hemoglobins correlated significantly with values for fasting plasma glucose (r = 0.52, n = 17, p less than 0.05) in these patients and with mean glucose measurements in five diabetic patients who used home glucose monitoring (r = 0.91, p less than 0.05). Contrary to studies with ion-exchange chromatography, our measurements of glycated hemoglobin showed no positive correlation with concentrations of urea in serum. In a separate group of patients, we found that hemodialysis sessions produced no acute effect on glycated hemoglobin. Measurements of glycated hemoglobins by analytically specific methods may thus better reflect long-term control of blood glucose in renal dialysis.

Specific affinity-chromatographic measurement of glycated hemoglobins in uremic patients

The clinical utility of glycated hemoglobin measurements in renal failure is controversial, given numerous earlier studies showing no correlation between glycated hemoglobin and other indicators of blood glucose control in uremic subjects. This problem is attributable, in part, to analytical interferences from carbamylated hemoglobins. We report use of a specific affinity method to measure glycated hemoglobins in a group of uremic patients, diabetic and nondiabetic, undergoing treatment by continuous ambulatory peritoneal dialysis. Concentrations of glycated hemoglobins correlated significantly with values for fasting plasma glucose (r = 0.52, n = 17, p less than 0.05) in these patients and with mean glucose measurements in five diabetic patients who used home glucose monitoring (r = 0.91, p less than 0.05). Contrary to studies with ion-exchange chromatography, our measurements of glycated hemoglobin showed no positive correlation with concentrations of urea in serum. In a separate group of patients, we found that hemodialysis sessions produced no acute effect on glycated hemoglobin. Measurements of glycated hemoglobins by analytically specific methods may thus better reflect long-term control of blood glucose in renal dialysis.

Improved liquid-chromatographic determination of 3-methoxy-4-hydroxyphenylethyleneglycol in urine with electrochemical detection

In this improved method for quantifying 3-methoxy-4-hydroxyphenylethyleneglycol (MHPG) in urine, after a multistep extraction of MHPG and internal standard (iso-MHPG) from 3.0 mL of urine, the compounds are separated on a C18 reversed-phase column and quantified by use of an electro-chemical detector. The isocratic chromatographic separation takes about 16 min. The mobile phase is phosphate buffer/acetonitrile (88/12 by vol), the flow rate 0.7 mL/min. Recycling the mobile phase and automating the sample injection make possible the unattended assay of more than 70 samples per day. The within-run precision of the method is excellent (CV 1.8%) at a mean concentration of 1.1 mg/L.

Improved liquid-chromatographic determination of 3-methoxy-4-hydroxyphenylethyleneglycol in urine with electrochemical detection

In this improved method for quantifying 3-methoxy-4-hydroxyphenylethyleneglycol (MHPG) in urine, after a multistep extraction of MHPG and internal standard (iso-MHPG) from 3.0 mL of urine, the compounds are separated on a C18 reversed-phase column and quantified by use of an electro-chemical detector. The isocratic chromatographic separation takes about 16 min. The mobile phase is phosphate buffer/acetonitrile (88/12 by vol), the flow rate 0.7 mL/min. Recycling the mobile phase and automating the sample injection make possible the unattended assay of more than 70 samples per day. The within-run precision of the method is excellent (CV 1.8%) at a mean concentration of 1.1 mg/L.

Determination of bethanidine in plasma by liquid-chromatography with a microbore reversed-phase column

In this novel method for quantifying bethanidine in plasma, after a multi-step extraction of bethanidine and internal standard from 2.0 mL of plasma, the drugs are separated on a "microbore" C18 reversed-phase column and quantified by their ultraviolet absorbance at 210 nm. The isocratic chromatographic separation takes about 15 min with use of an ion-pairing regent in the mobile phase (acetate buffer/acetonitrile, 9/1 by vol) and a flow rate of 0.25 mL/min. Sensitivity is increased relative to conventional columns, and solvent consumption is reduced by 90%. The standard curve is linear to at least 5 mg/L, and the detection limit is 0.02 mg/L. The within-run precision of the method is excellent (CV 4%) at a midrange concentration of 1.25 mg/L.

Determination of bethanidine in plasma by liquid-chromatography with a microbore reversed-phase column

In this novel method for quantifying bethanidine in plasma, after a multi-step extraction of bethanidine and internal standard from 2.0 mL of plasma, the drugs are separated on a "microbore" C18 reversed-phase column and quantified by their ultraviolet absorbance at 210 nm. The isocratic chromatographic separation takes about 15 min with use of an ion-pairing regent in the mobile phase (acetate buffer/acetonitrile, 9/1 by vol) and a flow rate of 0.25 mL/min. Sensitivity is increased relative to conventional columns, and solvent consumption is reduced by 90%. The standard curve is linear to at least 5 mg/L, and the detection limit is 0.02 mg/L. The within-run precision of the method is excellent (CV 4%) at a midrange concentration of 1.25 mg/L.

Prostaglandins and cancer

This paper reviews the role of prostaglandins (PGs) in cancer. Specific topics of discussion include: (1) the potential use of PGs as tumor markers, (2) PG mediation of hypercalcemia of cancer, and (3) the use of PG synthesis inhibitors in cancer therapy.

Erythrocyte creatine in cord blood

Erythrocyte creatine (EC) content and reticulocyte counts were compared in normal adults, pediatric patients with hemolytic anemia, and cord blood. A good correlation between reticulocyte count and EC content was found in normal subjects and patients with hemolysis, thus confirming the usefulness of creatine as an estimate of mean red cell age in these populations. No significant correlation (p greater than 0.1) was observed between the two measurements in cord blood. While reticulocyte counts were significantly elevated (p less than 0.001) in cord blood when compared to normal adults (indicating the presence of a young mean red cell age), EC concentrations in most samples were not correspondingly high. These results may indicate that creatine is not well synthesized by the neonatal red blood cell.

Improved determination of aluminum in serum by electrothermal atomic absorption spectrophotometry

This method for determining aluminum in human serum involves electrothermal atomic absorption spectrophotometry. A longer drying time allows less pre-dilution of the sample, and the method also includes a flush cycle after atomization. Standard-addition methodology is used to eliminate matrix effects and the need for a standard curve. We used this method on serum from 50 normal persons and from 34 patients with chronic renal failure who were on long-term intermittent hemodialysis. The mean normal serum aluminum concentration was 6.1 micrograms/L (CV 2.7%), and values for the patients ranged from 13 to 475 micrograms/L.

Improved determination of aluminum in serum by electrothermal atomic absorption spectrophotometry

This method for determining aluminum in human serum involves electrothermal atomic absorption spectrophotometry. A longer drying time allows less pre-dilution of the sample, and the method also includes a flush cycle after atomization. Standard-addition methodology is used to eliminate matrix effects and the need for a standard curve. We used this method on serum from 50 normal persons and from 34 patients with chronic renal failure who were on long-term intermittent hemodialysis. The mean normal serum aluminum concentration was 6.1 micrograms/L (CV 2.7%), and values for the patients ranged from 13 to 475 micrograms/L.

Clinical laboratory evaluation of Ames' Seralyzer Reflectance Photometer for total bilirubin and cholesterol

We evaluated the dry-reagent technology for determining cholesterol and adult total bilirubin in serum with the Ames Seralyzer Reflectance Photometer. This instrument is designed to measure the intensity of light of a selected wavelength that is reflected from reagent-impregnated test strips saturated with sample. Regression analysis of the data for total bilirubin in adults (y) compared with corresponding values obtained with the Technicon SMAC (x) yielded the regression line: y = 1.07x + 2.5 (n = 128, r = 0.99). Day-to-day precision (CV) was 3.8% at 8.1 mg of bilirubin per liter, 5.34% at 48.3 mg/L. Regression analysis of the cholesterol data (y) vs cholesterol values obtained with an enzymatic cholesterol method (x) yielded the regression line: y = 0.91x + 191 mg/L (n = 100, r = 0.98). Day-to-day CVs for cholesterol were 3.6% at 1.62 g/L, 3.11% at 2.62 g/L.

Clinical laboratory evaluation of Ames' Seralyzer Reflectance Photometer for total bilirubin and cholesterol

We evaluated the dry-reagent technology for determining cholesterol and adult total bilirubin in serum with the Ames Seralyzer Reflectance Photometer. This instrument is designed to measure the intensity of light of a selected wavelength that is reflected from reagent-impregnated test strips saturated with sample. Regression analysis of the data for total bilirubin in adults (y) compared with corresponding values obtained with the Technicon SMAC (x) yielded the regression line: y = 1.07x + 2.5 (n = 128, r = 0.99). Day-to-day precision (CV) was 3.8% at 8.1 mg of bilirubin per liter, 5.34% at 48.3 mg/L. Regression analysis of the cholesterol data (y) vs cholesterol values obtained with an enzymatic cholesterol method (x) yielded the regression line: y = 0.91x + 191 mg/L (n = 100, r = 0.98). Day-to-day CVs for cholesterol were 3.6% at 1.62 g/L, 3.11% at 2.62 g/L.

Measurement of plasma prostaglandin E2 using capillary gas chromatography negative ion chemical ionization mass spectrometry

A stable isotope dilution assay for the measurement of plasma prostaglandin E2 (PGE2) employing capillary column gas chromatography-negative ion chemical ionization mass spectrometry (GC-NICIMS) is described. PGE2 was extracted from plasma using C18 and silica SEP-PAKS. Further purification and separation was accomplished by thin layer chromatography. The prostaglandin was analyzed as its pentafluorobenzyl ester-methoxime-trimethyl-silyl ether, using fragment ions at m/e 524 (protium) and m/e 528 (deuterium) for quantitation. The mean plasma concentration of PGE2 determined in 8 healthy volunteers was 2.8 +/- 2.0 pg/ml.

Frequency of hypomagnesemia in hypokalemic states

Although both hypokalemia and hypomagnesemia have been linked with life-threatening cardiac arrhythmias, published studies disagree regarding the frequency of simultaneously low serum potassium and magnesium concentrations. To investigate the possible associations between the concentrations of these ions in serum, we carried out a retrospective study of all paired magnesium-potassium measurements reported from our laboratory during two separate two-week periods. Of 963 paired measurements in 421 patients, 12% of the samples were hypokalemic and 26% were hypomagnesemic. The frequency of hypomagnesemia was significantly greater in hypokalemic samples (38%) compared with nonhypokalemic samples (25%). The potential clinical importance of this relationship requires further investigation.

Frequency of hypomagnesemia in hypokalemic states

Although both hypokalemia and hypomagnesemia have been linked with life-threatening cardiac arrhythmias, published studies disagree regarding the frequency of simultaneously low serum potassium and magnesium concentrations. To investigate the possible associations between the concentrations of these ions in serum, we carried out a retrospective study of all paired magnesium-potassium measurements reported from our laboratory during two separate two-week periods. Of 963 paired measurements in 421 patients, 12% of the samples were hypokalemic and 26% were hypomagnesemic. The frequency of hypomagnesemia was significantly greater in hypokalemic samples (38%) compared with nonhypokalemic samples (25%). The potential clinical importance of this relationship requires further investigation.

Erythrocyte creatine levels in anemia

The automated diacetyl-l-napthol procedure was found to be a simple and relatively quick method for the determination of erythrocyte creatine (EC), exhibiting both better precision and greater sensitivity than reticulocyte counting. A reference range of 1.8 to 5.0 mg per dl (mean, 3.0 +/- 0.9 mg per dl) was established by measuring EC levels in 81 normal adults varying in ages from 20 to 47 years of age. Normal creatine values displayed a slight sex dependency, with females exhibiting somewhat higher levels than males. In evaluating the relative usefulness of EC versus reticulocyte counting in the assessment of anemia, both parameters were measured and compared in 41 patients with various hemolytic and nonhemolytic anemias. A direct relationship was noted between the two parameters (p less than 0.0001); however, the actual data correlation was only fair (r = 0.49). In a serial study of an iron-deficiency anemic patient responding to iron administration, erythrocyte creatine levels were found to rise more slowly than the reticulocyte count and to remain elevated after the reticulocyte count had returned to normal.

Serum lactate dehydrogenase isoenzymes in the diagnosis of myocardial infarction

The ratio of lactate dehydrogenase (LD-1:LD-2) in serum was studied in 101 patients admitted to a coronary care unit. The clinical reliability of the test could not be predicted from the normality or abnormality of the total serum lactate dehydrogenase (LD) activity. However, for samples with total LD activity below the middle of the normal range, no information was provided by the test. In contrast, the test provided reliable information when the total LD activity in the specimen was above the middle of the reference range (220 IU per L).

Cerebrospinal fluid prognostic indices in experimental pneumococcal meningitis

The prognostic value of initial and sequential determinations of quantitative bacterial concentrations, leukocytes, glucose, lactate, lactic acid dehydrogenase, and creatine phosphokinase in CSF was examined in rabbits with experimental pneumococcal meningitis while they were receiving equivalent, rapidly bactericidal antibiotic therapy. The following mean CSF variables correlated with death due to meningitis: (1) an early (day 1) high bacterial titer and lactate concentration with simultaneous low leukocyte count and glucose level and (2) late (day 3) elevated lactate and lactic acid dehydrogenase levels and leukocyte count. A high concentration of bacteria inoculated into the CSF and a high plasma glucose level also adversely influenced prognosis. Careful analysis of these variables may identify high-risk patients with pneumococcal meningitis and ultimately may be useful in gauging the therapeutic response.

Clinical studies of protein-bound calcium in various diseases

A recently developed gel-filtration technique allows protein-bound calcium fractions to be separated and quantitated; the protein is separated under physiological conditions of pH, temperature, and concentrations of Na, Mg, and Ca to assure that the calcium-proteinate equilibrium is not disturbed. We used this gel-filtration technique to study the protein-bound calcium fractions in 18 patients with hyperparathyroidism, multiple myeloma, diabetes, osteoporosis, or liver cirrhosis. We calculated the amount of calcium bound per gram of protein for each of the three protein peaks and the intrinsic association constant (Ka) for calcium/albumin. Results with the multiple myeloma patients (three IgG, one IgA) indicated that IgG did not bind calcium appreciably, that IgA had about the same affinity as albumin for Ca, and that Ka was slightly low for one patient of the IgG type (79 L/mol) and normal for the other three myeloma patients (106, 90, and 91 L/mol). Results for patients with the other diseases were also essentially normal, except for the osteoporesis patients (two men, one woman), whose Ka values (69, 75, and 73 L/mol) were lower than normal.

Clinical studies of protein-bound calcium in various diseases

A recently developed gel-filtration technique allows protein-bound calcium fractions to be separated and quantitated; the protein is separated under physiological conditions of pH, temperature, and concentrations of Na, Mg, and Ca to assure that the calcium-proteinate equilibrium is not disturbed. We used this gel-filtration technique to study the protein-bound calcium fractions in 18 patients with hyperparathyroidism, multiple myeloma, diabetes, osteoporosis, or liver cirrhosis. We calculated the amount of calcium bound per gram of protein for each of the three protein peaks and the intrinsic association constant (Ka) for calcium/albumin. Results with the multiple myeloma patients (three IgG, one IgA) indicated that IgG did not bind calcium appreciably, that IgA had about the same affinity as albumin for Ca, and that Ka was slightly low for one patient of the IgG type (79 L/mol) and normal for the other three myeloma patients (106, 90, and 91 L/mol). Results for patients with the other diseases were also essentially normal, except for the osteoporesis patients (two men, one woman), whose Ka values (69, 75, and 73 L/mol) were lower than normal.

Aluminum distribution in serum following hemodialysis

Aluminum is a toxic metal and has been implicated as the causative agent in the dialysis encephalopathy syndrome. In the study reported here, the transfer of aluminum to the blood from dialysis fluid during hemodialysis was demonstrated even when deionized water was used in the preparation of the dialysate. Studies were carried out on the binding of aluminum to serum proteins and other constituents in patients on long-term hemodialysis. Five major aluminum peaks were observed on chromatographic separation; four were associated with proteins and one large peak was probably associated with a low molecular weight species. The size of the latter peak was enhanced by increasing the aluminum content of the eluting buffer. It is postulated that this low molecular weight species might be the neurotoxic form of aluminum.

Disorders of calcium homeostasis in the fetus and neonate

The physiological mechanisms involved in the alterations in calcium homeostasis during pregnancy are complex. The fetal acquisition of calcium, for skeletal growth, is obtained by an increase in intestinal calcium absorption in the mother with transplacental calcium transfer to the fetus. The regulation of calcium homeostasis during the transition from the intrauterine to the extrauterine environment is complex and poorly understood. Within the first few hours of life the serum calcium concentrations begins to fall progressively reaching a "trough" value by the second or third day of life and then increases to normal values by the tenth day of life. In some neonates the fall in calcium concentration is sufficient to be associated with either tetany or convulsions. Hypocalcemia is probably the commonest disturbance of calcium homeostasis that occurs in the neonate and can be subdivided into three main groups on the basis of the etiological mechanism involved. Other disorders of calcium homeostasis that may affect the neonate include hypoparathyroidism, either congenital or acquired, pseudohypoparathyroidism, and vitamin D deficiency. Hypercalcemia may occur, but is a relatively rare occurrence in the neonate.

Effect of ultrasound-induced hyperthermia and cis-diamminedichloride platinum II on murine renal function

Murine renal function was evaluated after ultrasound-induced kidney hyperthermia (42.5 degrees C and 46.5 degrees C for 35 minutes) and the administration of cis-diamminedichloride platinum II (8 mg/kg). A quantitative immunonephelometric technique was employed to determine urinary total protein (TP) and albumin (Alb) 1-180 days post-treatment. Hyperthermia of 46.5 degrees C elevated urinary TP excretion significantly more than that of 42.5 degrees C cis-diamminedichloride platinum (Cis DDP) administration greatly increase urine TP with a peak mean TP concentration of 488 microgram/ml, four days after Cis DDP (normal range was 26-48 microgram/ml). This returned to normal by day 14. The TP excretion after 42.5 degrees C hyperthermia with concurrent Cis DDP was similar to Cis DDP alone, implying there was no potentiation of early or late Cis-DDP-induced renal damage by hyperthermia. Late mouse mortality was greater (P = 0.08) after Cis DDP alone, than Cis DDP with 42.5 degrees C hyperthermia. There was a statistically significant increase (P less than 0.05) in the Alb/TP excretion ratio after the addition of 42.5 degrees C hyperthermia to Cis DDP, implying an alteration in the site or nature of the Cis DDP renal lesion by hyperthermia.

Erythrocyte polyamine determinations in patients with head and neck cancer

Erythrocyte polyamine levels were measured in the blood from 29 untreated patients whose conditions were diagnosed as head and neck cancer. Only nine (31%) of these patients had elevations of erythrocyte spermidine and/or spermine levels above the reference ranges determined for normal persons. However, a positive correlation was observed between the erythrocyte spermidine levels and the clinical tumor stage. Serial erythrocyte polyamine determinations were performed on the blood from 12 of these patients before and after either surgical or radiation therapy. In 11 of the cases, the erythrocyte spermidine levels decreased after tumor therapy regardless of whether there was prior elevation above the reference range. The erythrocyte spermine levels in these patients were more variable in their response to tumor treatment. Therefore, although erythrocyte polyamine levels were only slightly to moderately elevated in response to the small tumors characteristic of the head and neck, the measurement of erythrocyte spermidine, potentially, may offer a simple and effective means of monitoring the course of therapy used in patients with head and neck cancer.

A multivariate approach to prognostication in experimental bacterial meningitis

Known concentrations of type III pneumococci were inoculated into eighty-one rabbits by cisternal puncture. Antibiotic therapy was started the following day. Aliquots of cerebrospinal fluid (CSF) and plasma were sampled on day one immediately before therapy was started and at regular intervals thereafter for up to eight days. Samples were analyzed for glucose, lactate, lactic dehydrogenase, and creatine kinase in various combinations. Leukocyte counts were performed on all CSF specimens. The timing of the specimens proved critical to the prognostic utility of the analyses performed. Day two plasma glucose was the most important single measurement for prognostication. Day one values for CSF glucose, lactate, and leukocyte count were also important. Substantial gains in prognostic accuracy were achieved when clinical laboratory measurements were used in combination by discriminant function analysis.

Aluminum toxicity in relation to kidney disorders

Aluminum toxicity in patients with chronic renal failure has been related to renal osteodystrophy and dialysis encephalopathy (DES). The toxicity is associated with renal osteodystrophy in two ways. One association is the iatrogenic effect of excessive use of aluminum hydroxide gels resulting in hypophosphatemia which interferes with bone mineralization. The second association may involve deposition of aluminum in bone owing to aluminum being absorbed during hemodialysis. Evidence for this second association has been gathered from epidemiological studies of hemodialysis centers and their practices of using either tap water high in aluminum in the dialysate, or aluminum-free deionized water. In patients with DES, aluminum accumulation in the brain has been clearly shown to come from either the ingestion of aluminum containing phosphate-binding gels, aluminum in the dialysate, or a combination of the two. The outbreak of the DES also has been well-correlated with the sudden elevation of aluminum in tap water owing to the use of large amounts of aluminum in water treatment plants. Whether aluminum itself or a combination of aluminum and other factors causes DES is not understood at this time.

Biochemistry of renal failure

The term uremia is used clinically to describe that state associated principally with the retention of nitrogenous metabolic products and is characterized by a raised blood urea concentration. The increase in the blood urea concentration is perhaps the most striking abnormality of the body fluids in renal failure, although it is not the most important functionally. The clinical syndrome of uremia involves all the systems of the body as a result of biochemical alterations in the constitution of the internal environment. The alterations in the latter compartment are due not only to the retained metabolic products but also to associated changes in water, electrolyte, and acid-base homeostasis. There are also features of the clinical syndrome of uremia which are attributable to variations in the rates of secretion and metabolism of a number of hormones in which the kidney is recognized to play a role, either directly or indirectly. This brief review deals with the retained uremic metabolites and their biochemical significance in the clinical syndrome of uremia. The metabolites discussed include urea, creatinine, guanidines and related compounds, uric acid, dimethylamine, and the middle molecule hypothesis. The potential role of some of these metabolites is discussed with regard to their potential toxic role as enzyme inhibitors. The biochemical aspects of uremic neuropathy are reviewed to highlight the biochemical complexity of the investigation of the uremic syndrome.

Secondary hyperparathyroidism in chronic renal failure

The metabolic bone disease associated with chronic renal failure has been described collectively by the terms "renal osteodystrophy" or "renal-glomerular-osteodystrophy" and consists of osteomalacia, osteitis fibrosa, and osteosclerosis. The skeletal abnormalities may occur either alone or in combination with one another. An increased concentration of circulating immunoreactive-parathyroid hormone (i-PTH) is a recognized feature of patients with chronic renal failure, and the values are usually much higher than those found in patients with primary hyperparathyroidism associated with a parathyroid adenoma. It must, however, be recognized that the high circulatory concentrations of parathyroid hormone found in patients with chronic renal failure are of immunoassayable material which may or may not be of biological significance in respect of activity. A disturbance in the homeostatic control mechanism governing parathyroid hormone, the secretion rate, its metabolism, and target organ resistance to its action are of major importance in the pathogenesis of some aspects of the metabolic bone disease in patients with chronic renal failure. The pathogenesis of the secondary hyperparathyroidism of chronic renal failure, however, also involves disturbances in cholecalciferol metabolism, phosphate retention, and the uremic state per se.

Prostatic acid phosphatase as measured with two radioimmunoassay kits in the detection of prostatic adenocarcinoma

Serum prostatic acid phosphatase concentration was measured with two commercially available radioimmunoassay kits. Results were compared with histological evidence of prostatic adenocarcinoma obtained at autopsy in 33 patients. The serum assay did not differentiate significantly (p greater than 0.1) between patients with adenocarcinoma and those without. We conclude that the test, at least as performed by use of these kits, is of little value in the detection of occult disease.

Prostatic acid phosphatase as measured with two radioimmunoassay kits in the detection of prostatic adenocarcinoma

Serum prostatic acid phosphatase concentration was measured with two commercially available radioimmunoassay kits. Results were compared with histological evidence of prostatic adenocarcinoma obtained at autopsy in 33 patients. The serum assay did not differentiate significantly (p greater than 0.1) between patients with adenocarcinoma and those without. We conclude that the test, at least as performed by use of these kits, is of little value in the detection of occult disease.

Plasma hydroxyproline fractions in patients with dialysis osteodystrophy

Plasma hydroxyproline fractions were measured in 17 normal subjects and in 54 patients on maintenance haemodialysis therapy (MHT) with various degrees of dialysis osteodystrophy. On the basis of both radiological and histological findings these patients were divided into three groups: radiologically normal, histologically normal and those with osteitis fibrosa. The mean total plasma hydroxyproline concentrations were significantly elevated in all groups of MHT patients. However, these increases were mainly due to peptide-bound and free hydroxyproline fractions. The highest values for these two fractions were found in patients with osteitis fibrosa. The free to peptide-bound hydroxyproline ratio was not significantly altered in the majority of patients on dialysis; the mean ratio was significantly lower in patients with osteitis fibrosa when compared with patients with no histological evidence of bone disease. This finding would suggest that there is no inhibition of hydroxyproline catabolism in patients on haemodialysis and the measurements of both free and peptide-bound hydroxyproline were equally sensitive in identifying patients with osteitis fibrosa.

The clinical biochemistry of aluminum

The methods for aluminum analysis vary from the simple and often nonspecific chemical and physical procedures to the highly sophisticated types such as neutron activation and atomic absorption spectrometry. Atomic absorption procedures are the techniques of choice for most routine hospital laboratories. The wide distribution of aluminum in nature can create severe contamination problems in aluminum analysis. Procedures to avoid contamination are discussed. In recent years aluminum has been implicated as a possible etiological agent in DES and in Alzheimer's Disease. A common finding in these two conditions is an elevated brain aluminum content. The patients with Alzheimer's Disease develop characteristic neurofibrillary tangles which lead to the degeneration of the affected neurons. Similar tangles can be induced in laboratory animals injected intracerebrally with aluminum salts. Even though the laboratory animals develop tangles resembling those seen in patients with Alzheimer's Disease, no evidence has been published to show that the tangles seen in Alzheimer's Disease are induced by the elevated brain aluminum content. Although there are some similar clinical symptoms in both Alzheimer's Disease and DES, the hemodialysis patients with DES do not develop neurofibrillary tangles despite an elevated brain aluminum content. The significance of this difference is not understood. The sources of the increase in tissue aluminum levels found in hemodialysis patients are from the gastrointestinal absorption of aluminum in aluminum containing phosphate-binding gels and by transfer from the dialyzate to the blood during the hemodialysis procedure. Plasma aluminum values may be reduced by the administration of a minimum dosage of phosphate-binding gels and by the use of purified water to make up the dialysate. The incidence of DES is reduced by the use of these procedures to maintain the hemodialysis patients' plasma aluminum at a low concentration. The increased brain aluminum content of patients with Alzheimer's Disease is derived from the environment. Because of the ubiquitous occurrence of aluminum, we are exposed to it daily in our food, water, and in the air. The low levels of aluminum absorbed from the environment may explain why susceptible patients do not develop Alzheimer's Disease until after many years of exposure, if indeed aluminum is the etiological agent in Alzheimer's Disease. The many papers that have been published concerning aluminum, DES, and Alzheimer's Disease make a strong case for linking elevated tissue aluminum content with these conditions. However, conclusive evidence to support this theory has not been published. Until the effect of aluminum on cellular chemistry is more fully understood, the possibility that DES and Alzheimer's Disease may result from other causes or from aluminum and another agent acting concomitantly must be considered.

Evaluation of the IFCC-recommended procedure for serum aspartate aminotransferase as modified for use with the centrifugal analyzer

The IFCC-recommended procedure for aspartate aminotransferase (EC 2.6.1.1) was adapted to the centrifugal analyzer and evaluated during five years. The main hindrance to widespread use of the recommended method is the need for pre-incubation with pyridoxal phosphate. The present method includes a 10-min pre-incubation with pyridoxal phosphate. Extensive evaluation of the method with and without this pre-incubation confirms earlier reports that it eliminates some significant errors, especially for samples from patients with cardiac disease. However, the pre-incubation can be briefer than the recommended 10 min and still provide acceptable results.

Evaluation of the IFCC-recommended procedure for serum aspartate aminotransferase as modified for use with the centrifugal analyzer

The IFCC-recommended procedure for aspartate aminotransferase (EC 2.6.1.1) was adapted to the centrifugal analyzer and evaluated during five years. The main hindrance to widespread use of the recommended method is the need for pre-incubation with pyridoxal phosphate. The present method includes a 10-min pre-incubation with pyridoxal phosphate. Extensive evaluation of the method with and without this pre-incubation confirms earlier reports that it eliminates some significant errors, especially for samples from patients with cardiac disease. However, the pre-incubation can be briefer than the recommended 10 min and still provide acceptable results.

Evaluation of an automated radioimmunoassay for serum cortisol

The performance characteristics are reported for a serum cortisol assay using the GAMMAFLO Automated Assay System, an automated continuous-flow system for radioimmunoassay (RIA). This automated system utilizes a combination of continuous-flow methodology and column chromatography techniques. The cortisol assay studied had a standard curve range of 10.0 to 500 microgram per L. The intra-assay and inter-assay precision were 5.1 percent and 7.2 percent (RSD), respectively, for a cortisol concentration of 160 microgram per L. The automated serum cortisol results correlated (r = 0.958 and 0.933) with two established manual radioimmunoassay procedures. No drift or carryover was detectable in 200 within-assay consecutive determinations performed at a rate of 42 determinations per hour (five hours continuous operation). The automated system studied appears to offer a viable alternative to cortisol manual RIA techniques in terms of overall precision simplicity of operation, and sample throughput.

Automated multiple flow-injection analysis in clinical chemistry: determination of total protein with Biuret reagent

We have examined the feasibility of the automated multiple flow-injection technique for application to clinical chemistry by adapting to this system the biuret method for the determination of total protein. Samples were discretely and rapidly introduced into a continuously flowing, nonsegmented reagent stream by means of an automatic sampler and high-pressure injection valve. Pumps operating at 1380-2070 kPa (200-300 psi) were utilized to introduce the biuret reagent and saline diluent into the system separately at flow rates of 72 and 47 microL/s, respectively. Use of 20-microL sample and a 3.0-s reaction-delay coil was adequately sensitive for analysis for total protein by this method. Samples were analyzed at a rate of 150/h with no detectable between-sample carryover. Within-run precision studies yielded relative standard deviations of 2.5% and less. Total protein values obtained by this method correlated well with those obtained by centrifugal analyzer and bubble-segmented continuous-flow biuret methods.

Automated multiple flow-injection analysis in clinical chemistry: determination of total protein with Biuret reagent

We have examined the feasibility of the automated multiple flow-injection technique for application to clinical chemistry by adapting to this system the biuret method for the determination of total protein. Samples were discretely and rapidly introduced into a continuously flowing, nonsegmented reagent stream by means of an automatic sampler and high-pressure injection valve. Pumps operating at 1380-2070 kPa (200-300 psi) were utilized to introduce the biuret reagent and saline diluent into the system separately at flow rates of 72 and 47 microL/s, respectively. Use of 20-microL sample and a 3.0-s reaction-delay coil was adequately sensitive for analysis for total protein by this method. Samples were analyzed at a rate of 150/h with no detectable between-sample carryover. Within-run precision studies yielded relative standard deviations of 2.5% and less. Total protein values obtained by this method correlated well with those obtained by centrifugal analyzer and bubble-segmented continuous-flow biuret methods.

Serum parathyroid hormone concentrations in senile dementia (Alzheimer's disease)

The accumulation of aluminum in the cerebral cortex has been implicated as a factor in the pathogenesis of Alzheimer type senile dementia (SD) and in the dialysis dementia found in patients with chronic renal failure on long-term intermittent hemodialysis treatment. In animal studies, parathyroid hormone (PTH) produces increased absorption of aluminum from the gastrointestinal tract and elevations of aluminum in the cerebral cortex. It has been proposed that PTH elevations may increase tissue aluminum loads in patients with senile dementia. The present study was undertaken to investigate the status of circulating PTH in patients with SD and age/sex matched controls. No significant differences were found between these groups. Elevated PTH (when it did occur) seemed to be related to the degree of renal impairment rather than dementia. Differences in the distribution of aluminum in patients with dialysis dementia and SD are discussed.

Rapid centrifugal analyzer enzyme immunoassays for phenytoin, phenobarbital, and primidone

The adaptation of the homogeneous enzyme immunoassays (EMIT) for phenytoin, phenobarbital, and primidone to a centrifugal analyzer is described. The sample volume required was 10 microliter, and the assay had the capacity to analyze sera from 28 patients within 180 sec. The assay temperature was 30 C, and absorbance was monitored at 340 nm. Coefficients of variation for within-day precision ranged from 2.1% to 3.7%, and analytic recovery was quantitative. The centrifugal analyzer EMIT assay results correlated well with those obtained using high-pressure liquid and gas-liquid chromatographic technics. A logit-log transformation of the absorbance rate versus concentration data was obtained using a modified Gauss-Newtonian nonlinear least-squares fit analysis. Severe hemolysis and lipemia caused interference.

Homogeneous enzyme immunoassay for theophylline with a centrifugal analyzer

A rapid homogeneous enzyme immunoassay for theophylline has been adapted to a centrifugal analyzer. The sample volume used was 10 microliter and sera from as many as 28 patients could be measured in 180 seconds. The assay temperature was 30 degrees and the absorbance rates were measured at 340 nm. Within-run and run-to-run precision showed a coefficient of variation of less than 2.6 and 7.5 percent, respectively, for theophylline concentrations of 2.5 to 40 mg per liter. The method was linear to 50 mg per liter and the analytical recovery was quantitative. A comparison between high pressure liquid chromatography (X) and the centrifugal analyzer enzyme immunoassay method (Y) for 51 patient samples revealed a correlation coefficient of 0.976 with a regression line of Y = 1.07 X -1.05 mg per liter. Reagent costs were reduced three-fold by adapting the enzyme immunoassay procedure from a semi-automatic spectrophotometer to a centrifugal analyzer. An absorbance rate for each theophylline sample was obtained by a multipoint kinetic rate computer program by the centrifugal analyzer. Severe hemolysis and lipemia interfered in this assay.

Erythrocyte polyamine levels in rats with H4IIE hepatomas before and after radiation treatment

The concentration of the polyamines, spermidine and spermine associated with the erythrocytes of rats with H-4-II-E hepatomas increased with tumor growth. Following radiation therapy the erythrocyte spermidine and spermine levels decreased by 63 and 47% respectively. Six days after radiation treatment the erythrocyte polyamines had increased to the pre-treatment elevated levels. These data suggest that erythrocyte polyamine levels may be useful in assessing the response to therapy and in detecting the continued growth of the tumor in patients with malignant disease.

Automated multiple flow-injection analysis in clinical chemistry: determination of albumin with bromcresol green

We describe an adaptation of automated multiple flow-injection analysis instrumentation to an analysis for albumin in serum. The bromcresol green reaction was used to test the utility of the system. The approach yielded albumin results with excellent sensitivity, no measurable carryover, a relative standard deviation of less than 1%, good correlations with published procedures, and no measurable interferences. The simplicity and flexibility of the instrumentation and its performance integrity, as indicated by the analytical results, make this a viable clinical chemical tool.

Automated multiple flow-injection analysis in clinical chemistry: determination of albumin with bromcresol green

We describe an adaptation of automated multiple flow-injection analysis instrumentation to an analysis for albumin in serum. The bromcresol green reaction was used to test the utility of the system. The approach yielded albumin results with excellent sensitivity, no measurable carryover, a relative standard deviation of less than 1%, good correlations with published procedures, and no measurable interferences. The simplicity and flexibility of the instrumentation and its performance integrity, as indicated by the analytical results, make this a viable clinical chemical tool.

Automated multiple flow-injection analysis in clinical chemistry: determination of albumin with bromcresol green

We describe an adaptation of automated multiple flow-injection analysis instrumentation to an analysis for albumin in serum. The bromcresol green reaction was used to test the utility of the system. The approach yielded albumin results with excellent sensitivity, no measurable carryover, a relative standard deviation of less than 1%, good correlations with published procedures, and no measurable interferences. The simplicity and flexibility of the instrumentation and its performance integrity, as indicated by the analytical results, make this a viable clinical chemical tool.

Clearance of [14C] polyamines from plasma and erythrocytes in the rat

The [14C] polyamines, putrescine, spermidine and spermine were administered intravenously to rats. Arterial blood samples were obtained 2, 4, 6, 12, 20, 30, 60 and 120 min. after injection. Plasma and erythrocyte fractions were separated and assayed for [14C] activity. The clearance of radiolabelled polyamines from both the plasma and erythrocytes was rapid. Within 10 min. of injection, plasma putrescine had decreased by 70%, spermine by 80% and spermidine by 85%. In the same time interval the erythrocyte putrescine level had decreased by 50%, spermine by 70% and spermidine by 80%. This data suggests that exogenously injected radiolabelled polyamines and presumably endogenously produced polyamines are rapidly cleared from the circulation.