Pressure dependence of the radioactive decay constant of beryllium-7.

Diamond anvil presses of a new design were used to compress samples of beryllium-7 oxide to 120, 210, and 270 kilobars. The decay constant for the conversion of beryllium-7 to lithium-7 by electron capture was measured for compressed and uncompressed samples. A least-squares fit of the equation (lambda(c)-lambda)/lambda = KpP to the experimental data, where lambda(C) and lambda are the decay constants of the compressed sample and an uncompressed sample, respectively, and P is pressure, yields a value of (2.2 +/- 0.1) x 10(-5) kbar(-1) for the constant K(p).

Manganese-52m, a new short-lived, generator-produced radionuclide: a potential tracer for positron tomography.

A new generator system has been developed using the Fe-52 leads to Mn-52m parent-daughter pair. Fe-52, half-life 8.3 hr, is isolated on an anion-exchange column, and Mn-52m is eluted in hydrochloric acid. Breakthrough is less than 0.01% and the yield is 75%. The 21.1-min half life of Mn-52m is ideal for use in sequential studies, but is long enough to permit radiochemical manipulations to control biodistribution. Animal studies indicate that Mn-52m is an ideal nuclide for myocardial imaging, combining rapid blood clearance and high concentration in the myocardium. An added advantage is that Mn-52m decays 98% by positron emission and is useful for positron computer tomography.

Arterial ammonia with Blood Ammonia Checker II and with indophenol reaction to assess presence of hepatic encephalopathy.

Hepatic encephalopathy (HE) is associated with elevated arterial ammonia levels. The relationship is variable, in part due to ammonia methodology. One method, based on the indophenol reaction (IPh), is interfered with a number of amino acids including all aromatic amino acids. We have determined arterial ammonia simultaneously with the Blood Ammonia Checker II (BAC) as reference method and with the IPh method. The difference BAC-IPh, mumol/l, was assumed to express the interference in the indophenol method (IFI) by amino acids. It may be positive or negative. The aim was to establish the value of BAC in comparison with IPh in the diagnosis of liver disease and overt HE and to assess any added value of IFI. Of two reference groups without disturbances, A (n = 39) had not and B (n = 13) had encephalopathy. Group C consisted of 125 liver patients (34 no cirrhosis, 91 cirrhosis) of which 55 had no manifest HE (C:HE-) and 70 had HE (C:HE+). Median BAC ammonia nitrogen (NH3-N), mumol/l: A 21, B 35, C 80, C:HE - 57 and C:HE+ 98 (A < B < C and A < B < C:HE - < C:HE +, P < 0.001). Median IPh NH3-N, mumol/l: A 27, B 30, C 30, C:HE - 25 and C:HE + 35 mumol/l (A = B = C and C:HE - < C:HE+, P < 0.01). IFI medians: A -6, B 3, C 40, C:HE - 29 and C:HE + 58 mumol/l (A < B (P < 0.05) < C (P < 0.0001); A, B < C:HE - and C:HE+; C:HE- < C:HE + (all P < 0.0001)). While BAC correlated weakly with IPh in the (sub)groups C, C:HE-, C:HE+ (r = 0.3, 0.3, 0.4, P < 0.05), it correlated strongly with IFI (r = 0.9, 0.9, 0.8, P < 0.0001). There was no correlation between IPh and IFI. BAC, as well as IFI, could discriminate all liver patients (C) from both reference groups A and B with 100% positive likelihoods. BAC, IPh and IFI could discriminate between HE- and HE+. To differentiate cirrhosis from non-cirrhosis the specificity of IPh was uniformly high and the sensitivity satisfactory, whereas BAC had a high sensitivity but an insufficient specificity. In conclusion, in blood, BAC is the ammonia determination of choice. It differentiates between reference groups (encephalopathic or not) and liver disease and the more so HE. The combination of BAC and IPh (indicating IFI) may eventually be shown useful to rapidly assess the severity of underlying liver disease in HE patients. In other biological fluids, IPh is excellent when the inhibiting influence of non-protein nitrogen substances is absent or can be eliminated.

Evaluation of gravimetric assays of the H2O concentration in human serum and urine.

The oven-drying method and the combined freeze- and oven-drying method for gravimetrical measurement of human serum and urine H2O concentration, as well as two reported formulas for the calculation of the serum H2O concentration were evaluated. Day-to-day precision in serum and urine (coefficient of variation (CV) less than 0.95%), and recovery in serum (95-99%) were excellent. Storage at 4 degrees C and at -20 degrees C was safe at least for 3 wk and 2 mth, respectively. For the oven-drying method, which was the most practical, reference values after fasting overnight were determined (n = 47; 99% confidence interval; serum, 48.8-51.6 mol/l; urine, 51.2-53.8 mol/l). Patients in different disease categories were tested (n = 38), and had normal values mostly. Low serum values were found in a patient after hemodialysis with ultrafiltration (47.0 mol/l), and in two patients with an extreme hyperproteinemia (48.8 mol/l) and hypercholesterolemia (48.1 mol/l), respectively. Formulas for calculation of the serum H2O concentration proved unreliable. When direct measurement is impossible, a serum value of 50.5 mol/l can be substituted.

Determination of ammonia in ear-lobe capillary blood is an alternative to arterial blood ammonia.

Blood ammonia determination is a laboratory test to diagnose hepatic encephalopathy. Arterial blood is superior to peripheral venous blood ammonia because of ammonia metabolism in muscle. We have compared capillary with arterial whole blood ammonia as capillary sampling is an attractive alternative. Ear-lobe capillary blood ammonia (ECA) was determined in all 173 persons studied, fingertip capillary blood ammonia (FCA) in 46 of these and arterial blood ammonia (AA) in 113. Of the 173, 60 were healthy (H), 64 were patients, not liver diseased (NLD) and 49 had liver disease (LD). Reference values, median and ranges, mumol NH3-N/l: AA, NLD, n = 64: 17 (7-42); ECA, H = NLD (P = 0.9), n = 124: 20 (7-45); FCA, H = NLD (P = 0.8), n = 33: 70 (29-151). Within the NLD group (n = 64) AA values (range 7-42) were little but significantly lower than the ECA values (range 7-45, P = 0.002). FCA NLD > AA NLD (n = 14, P < 0.0001); FCA H+NLD > ECA (n = 33, P < 0.0001). AA correlated very well with ECA, r = 0.87 (n = 113, P < 0.0001) and less well with FCA, r = 0.56 (n = 27, P < 0.01). ECA correlated with FCA, r = 0.51 (n = 46, P < 0.001). Ear-lobe capillary blood ammonia thus accurately reflects arterial ammonia and is an attractive alternative. The higher fingertip ammonia may be due to contamination with ammonia-rich sweat from finger grooves, regardless of the precautions taken.

Gravimetric determination of the water concentration in whole blood, plasma and erythrocytes and correlations with hematological and clinicochemical parameters.

We have assessed gravimetric methods for determination of intravascular water, established whole blood-, plasma- and erythrocyte water reference values in a healthy volunteer group (n = 97, 48 females) and correlated these variables with 30 simultaneous hematological, clinicochemical and body parameters. The water standard was 55.56 mol/kg = 100 mass %. For erythrocyte water determination three methods were evaluated: 2 indirect methods were easy to perform, the third, using a hematocrit centrifuge, was the most reliable. Imprecision (within-batch coefficient of variation (CV), %) was excellent: whole blood 0.2, plasma 0.1, erythrocytes 0.7-2.2 and recoveries (means, %) 99.7-100.1. Serum water was found to be slightly higher than plasma water. Volunteer group, mean reference values, mass %: whole blood water 79.7, plasma water 91.2, erythrocyte water, three methods 66.2, 64.6 and 64.2, respectively. Females had mean 1.6 mass % higher whole blood water and 0.9-1.0 mass % higher erythrocyte water than males with no difference in plasma water. In the volunteer group whole blood water correlated strongly with hematocrit (r = -0.96), hemoglobin (r = -0.94) and erythrocytes (r = -0.85) and centrifuge hematocrit (r = -0.91). Plasma water correlated strongly with plasma total protein (r = -0.74, all correlations P < 0.001). Hemoglobin and hematocrit can serve as surrogate parameters for whole blood water when water determination is not available; total protein reflects plasma water.

Whole blood and plasma water in health and disease: longitudinal and transverse observations and correlations with several different hematological and clinicochemical parameters.

In a healthy reference population, hemoglobin (Hgb) and hematocrit (Hct) have been proposed as surrogate markers for whole blood water (WBW). We have extended this study under different physiological and pathological conditions in two longitudinal series, viz. (1) acute hyper- and hypohydration experiments in a healthy individual and (2) three athletes running 5 km each, and in three transverse series, viz. (3) a young reference population (n = 97, 49 females), (4) an old reference population (n = 37, nine females) consisting of inhabitants of a nursing home and (5) cardiac, hematological and renal patients including severe anaemia, polycythaemia and abnormal protein levels (n = 50, 25 females) with suspected hydration disturbances. The only sex difference found was a lower WBW in males in the young reference group. The percentage change of PW was less than that of WBW. In all five groups together (n = 293) WBW correlated closely (P < 0.0001) with Hgb and Hct (both r = -0.95) and with erythrocyte count (r = -0.85), whereas PW correlated with total protein (Tprot) (r = -0.84). In the longitudinally studied groups (1) and (2) WBW also correlated (P < 0.0001) with cholesterol, Ca, Tprot, albumin, platelets, globulin and white blood cells (r +/- 0.98-0.37), while PW correlated (P < 0.0001) not only with the same clinicochemical parameters but also with Hct, Hgb and red blood cells (r +/- 0.98-0.44). The homeostasis of PW is more narrowly regulated than that of WBW. Hgb, Hct and erythrocyte count reflect WBW and Tprot reflects PW also under disease conditions. WBW (mass%) can be calculated from Hgb and Hct using the formulae: -0.09 x Hgb (g/l) + 91.7 and -28.6 x Hct (v/v) + 91.8 and PW (mass%) from Tprot using the formula: -0.09 x Tprot (g/l) + 97.6. Other correlations were observed only in a longitudinal setting and presumably are due to concentration and dilution.

Comparison of the precision of seven analytical methods for the H2O concentration in human serum and urine.

In order to calculate a true renal H2O clearance (U X V/P), serum and urine H2O concentrations have to be known. In this investigation we compared the precision (repeatability) and the ease of performance of 7 H2O assays in human serum and urine. The 3 gravimetric assays (oven-drying, freeze-drying or freeze-drying as well as oven-drying) had a very high precision (coefficients of variation (CV) 0.2-0.4%) and were easy to perform. The precision of mass spectrometry, gas chromatography and titrimetry (Karl Fischer) was better in urine than in serum (ranges of CV 1.2-1.5% in urine vs. 2.4-4.3% in serum), but the precision of osmometry was better in serum than in urine (CV 1.0 vs. 1.6%). Accuracy was not determined as storage effects at 4 degrees C and at -20 degrees C caused insuperable logistic problems. Only small sample volumes are used in titrimetry and gas chromatography, making them more suitable for determinations in babies and animal studies. With titrimetry determinations can be done in a short time. The gravimetric assays appear to reflect the true H2O content of serum and urine, thus enabling calculation of the true renal H2O clearance, which can be of clinical importance in liver, renal and cardiac disease.

Determination of blood ammonia using the Ammonia Checker.

A new diffusion method employing bromocresol green for determination of blood ammonia (Ammonia CheckerR) using disposable reagent test-plates and a pocket-size colorimeter with direct read-out of results was compared with an enzymatic method. The values obtained with the Ammonia Checker were slightly lower than those with the enzymatic method. Instead of arterial blood, capillary blood may be used for ammonia determination, but thorough cleansing of the fingertip used is necessary because of the high ammonia content of sweat.

Composition of human hepatic bile.

To define reference values of human hepatic bile for sodium, potassium, chloride, calcium, iron, copper, urea, creatinine, phosphate, glucose, bilirubin, cholesterol, protein, bile salts, phospholipids, ammonia, pH, PCO2, bicarbonate and osmolarity, bile was obtained via a T-drain from 12 adult patients who underwent cholecystectomy. Bile of females had a higher cholesterol concentration than that of males. The saturation index, however, was not different in both groups.

Quantification of liver iron concentration with magnetic resonance imaging by combining T1-, T2-weighted spin echo sequences and a gradient echo sequence.

BACKGROUND: The aim of the study was to quantify hepatic iron by MRI for practical use. METHODS: In twenty-three patients with various degrees of iron overload, measurements were carried out with a 1.5 Tesla MR unit. A combination of pulse sequences (T1, T2 and gradient echo) enabled us to quantify smaller amounts of liver iron as accurately as larger amounts of liver iron. The gradient echo sequence provided us with a good correlation when detecting smaller amounts of iron in the liver where the T1 sequence provided a good correlation when larger amounts of iron were present. RESULTS: The combination of the three sequences showed a nice correlation (r=-0. 93, P<0.001) and provided us with an accurate estimate of the liver iron content (LIC). This correlation was achieved with a LIC from the lower range of normal up to LIC of 146 mmol/kg dry weight, which seems the highest measurable liver iron content for a 1.5 Tesla MRI. Measuring in the lower range makes it possible to decide whether further invasive diagnostic investigations by a liver biopsy are indicated. CONCLUSION: MRI is a useful tool to quantify iron overload non-invasively. In cases where a liver biopsy is hazardous MRI can easily be used to obtain reliable, quantitative information about the initial LIC. Quantification by MRI could also be used for follow up of the iron content during depletion treatment by phlebotomy or iron chelation. The stronger the magnet the more sensitive the detection of concentrations up to 150 mmol/kg is. A semi-quantitative judgement will only be possible with severe iron overload over 150 mmol/kg. If such an iron excess is found, a liver biopsy should be performed to exclude cirrhosis.

Anti-HBc titers and anti-HBc immunoglobulin (M/G) classes in acute, chronic and resolved hepatitis B.

IgM-anti-HBc and IgG-anti-HBc serum titers were determined by indirect immunofluorescence in a prospective longitudinal study of 50 patients with hepatitis B, 43 of whom recovered completely. 37 of the recovered patients and all 7 non-recovering patients were followed up for a median of 5 years. Five of the non-recovering patients were followed up from the initial acute stage of the disease. IgM-anti-HBc was present in the acute stage in 39/43 of the recovery patients. The median maximal titer, 1:1000, was reached during the week before peak SGPT. It always disappeared in recovering patients within a median period of 5 weeks after peak SGPT. IgG-anti-HBc was present in all 43 recovering patients in the acute stage of disease with a median maximal titer of 1:1000, maintained for at least 10 weeks. After 5 years, 28 of 37 recovered patients were still IgG-anti-HBc positive with a median titer of 1:200. All non-recovering patients showed persistent IgM as well as IgG-anti-HBc positivity. In the acute stage the medians of the maximal titers were 1:100 for IgM-anti-HBc and 1:1000 for Igg-anti-HBc. After 5 years they were 1:100 for IgM and 1:10000 for IgG-anti-HBc. The presence of IgM-anti-HBc in a preceding study was considered to be a marker of hepatitis B virus replication. From this study no evidence can be obtained to support the view that the titer level of anti-HBc is reliable in the differentiation between infectious anti-HBc positive blood, as there was no difference (p = 0.4) between the number of patients with an anti-HBc level of 1:1000 after at least five years, who had recovered (9/28) and who had not recovered (3/7).

Preference and significance of HBeAg and anti-HBe, determined by enzyme immunoassay, in patients with acute, chronic and resolved hepatitis B.

HBeAg and anti-HBe were determined by enzyme immunoassay in a prospective longitudinal study of 50 patients with hepatitis B, 43 of whom recovered completely. Followup studies were possible in 37 of the recovered patients and in all 7 non-recovering patients for a median of 5 years. Five of the non-recovering patients could be followed up from the initial acute stage of the disease. HBeAg was present in 17 of 18 recovering patients from whom serum was still available from the early stage of disease (i.e. before peak SGPT levels were reached). The presence of HBeAg was transitory for a median period of one week before the peak SGPT level until it was actually attained. All HBeAg-positive serums contained HBsAg and IgM-anti-HB core as well. 39 of the 43 recovering patients developed anti-HBe, first present after a median period of 2 weeks after peak SGPT. After 5 years 25 of 30 tested patients were still anti-HBe positive, all were HBeAg (and HBsAg) negative. Of the non-recovering patients 2 remained HBeAg-positive for at least 4 years, 4 seroconverted to anti-HBe between 0.5 and 2.5 years after the acute stage of the disease, without apparent correlation with the biochemical activity or the histological diagnosis, and 1 patient already had anti-HBe in the acute stage of the disease. Thus HBeAg is as a rule transiently present in acute hepatitis B, during early stages of the disease. HBeAg has been regarded commonly as a viral constituent. The conversion from HBeAg to anti-HBe in the patients with chronic hepatitis B, however, may cast doubt on this assumption in favour of the hypothesis that the HBe/anti-HBe system is of host origin. Anti-HBe, when present without markers of virus replication, may serve as a sign of previous, completely resolved hepatitis B.

Primary biliary cirrhosis: Dutch application of the Mayo Model before and after orthotopic liver transplantation.

BACKGROUND/AIMS: A retrospective study of primary biliary cirrhosis (PBC) was performed to study the Original Mayo Model for predicting survival by a Dutch data-set of patients, presentation of disease progression; assessment of liver transplantation, prediction of post-transplantation survival; and the addition of two laboratory variables to the Original Mayo Model. MATERIALS AND METHODS: Survival of 83 patients, 37 of whom underwent transplantation, were studied. Mean follow-up was 6.0 +/- 0.45 SEM years. Risk score at diagnosis, platelet count, and serum sodium were analyzed in a Cox model. RESULTS: The Original Mayo Model estimated survival for low-, medium-, and high-risk groups accurately and it also presented disease progression. Baseline Mayo risk score in a Cox model had a regression coefficient of 1.01, indicating an excellent predictor p < 0.0001. Platelet count was a predictor of survival (p < 0.002), whereas serum sodium did not (p = 0.67). A new model combined of the Original Mayo risk score and platelet count predicted survival in high-risk patients somewhat better compared to the Original Mayo Model. With both models, liver transplantation had a significant beneficial effect on survival (p < 0.001). The scores revealed no significant influence (p = 0.47) for overall post-transplantation survival. CONCLUSIONS: The Original Mayo Model remains the model of choice for patients with PBC for prognostication from 3-8 years, is a useful tool in the assessment of liver transplantation but not an indicator of post-transplantation survival. Platelet count showed to have additional prognostic value. A new model combined of platelet count and the Original Mayo risk score did predict survival in high-risk groups slightly better compared to the Original Mayo Model.

Major clinical events, signs and severity assessment scores related to actual survival in patients who died from primary biliary cirrhosis. A long-term historical cohort study.

BACKGROUND/AIMS: One of the prognostic methods for survival in primary biliary cirrhosis (PBC) is the Mayo model, with a time-scale limited to 7 years. The aim of our study was to assess how major clinical events, signs, several severity assessment methods and Mayo survival probabilities fit in with actual patient survival, by using yearly observations until 0.5 years before patient death from PBC. METHODOLOGY: Data of 32 patients dying from PBC were collected prior to death at -0.5, -1, -2 etc. years (median: -5 years, range: -16 to -0.5 years). Major events registered were: first occurrence of ascites, upper gastrointestinal bleeding or manifest hepatic encephalopathy and signs, first observation of spider naevi or purpura. Severity assessment methods applied (all with scores and classes) were: Mayo (M), Child-Campbell (C), Pugh-Child (P), Pugh-Child-PBC (PP), 'Child-Pugh' (CP), and Ascites Nutritional State-Child (ANS). Fifty percent survival estimates were calculated from Mayo scores. Severity assessment method variables were: ascites (C, P, PP, CP, ANS), encephalopathy (C, P, PP, CP), nutritional state (C, ANS), edema (M), age (M), serum albumin (M, C, P, PP, CP), bilirubin (C, M, P, PP, CP), and prothrombin time (M, P, PP, CP). RESULTS: In 27 out of 32 patients a major event occurred, always between -6 and -0.5 years (median: -1 year) and, never between -16 and -7 years (p < 0.0001). A sign was first observed in 30/32 between -14 and -0.5 years (median: -2 years). Compared to the total population, a sign, and even more so, an event indicated a shorter survival (p = 0.004 and p = 0.0002, respectively). The median 50% estimated survival (predicted by the Mayo model) fitted the actual survival from -6 to -0.5 years (r = -0.7, p < 0.0001), but not from -16 to -7 years (r = -0.1, p = 0.4). All -6 to -0.5-year severity scores correlated (p < 0.0001) both with actual survival (M, C, P, PP, and CP r = 0.7; ANS r = 0.5) and with estimated M 50% survival (C, P, PP, CP r = -0.9; ANS r = -0.6; M score: -0.99), but none with actual survival from -16 to -7 years, except for M, slightly (r = -0.3, p = 0.04). A nomogram for mean C, CP, M and ANS scores related to actual survival was constructed for the -6 to -0.5-year period. The C and CP classes A, B, and C did not appear to distinguish sufficiently into actual survival, whereas the M classes did. CONCLUSIONS: The occurrence of a major event appeared to exclude survival over 6 years. In these final 6 years, Child-Campbell, Mayo and Pugh scores correlated equally well with actual survival and better than Ascites/Nutritional State score. In our PBC patients, Campbell was an excellent alternative for Pugh; for Pugh, the original Child-Turcotte variable limits were fully sufficient.