Determination of the circulating red cell volume in man by radioactive chromium

51Cr Red Blood Cells in the Study of Hematologic Disease: A Historical Review

The early years of nuclear medicine included the development and clinical use of several in vitro or nonimaging procedures. The use of radionuclides as replacements for nonradioactive dyes brought improved accuracies and less subjective measurements to indicator dilution studies of body compartments such as the gastrointestinal system, lungs, urinary system, and vascular space. A popular nuclear medicine procedure was the radionuclide dilution method for quantitation of whole-blood volume or red blood cell volume or mass using 51Cr-labeled red blood cells-an important diagnostic element in patients suspected of having polycythemia vera, congestive heart failure, hypertension, shock, syncope, and other abnormal blood volume disorders. The radionuclide dilution method led to improved evaluation of red blood cell survival, which is important for clinical treatment planning in anemia and confirmation of splenic sequestration of damaged red blood cells. Although it was discovered that 51Cr was a chemically stable radiolabel of red blood cells after binding to intracellular hemoglobin, few nuclear medicine departments offered the clinical study for referring physicians because it required laboratory expertise for technologists, patient coordination, and a time-consuming procedure. The introduction of improved methods that are less time-consuming and have clinically acceptable results, along with the discontinuation of the sodium chromate 51Cr injection radiopharmaceutical by manufacturers, has consigned 51Cr red blood cells for red blood cell volume, mass, or survival evaluation to the list of retired nuclear medicine studies.

Investigation of blood group genotype prevalence in Korean population using large genomic databases

Blood group antigens, which are prominently expressed in red blood cells, are important in transfusion medicine. The advent of high-throughput genome sequencing technology has facilitated the prediction of blood group antigen phenotypes based on genomic data. In this study, we analyzed data from a large Korean population to provide an updated prevalence of blood group antigen phenotypes, including rare ones. A robust dataset comprising 72,291 single nucleotide polymorphism arrays, 5318 whole-exome sequences, and 4793 whole-genome sequences was extracted from the Korean Genome and Epidemiology Study, Genome Aggregation Database, and Korean Variant Archive and then analyzed. The phenotype prevalence of clinically significant blood group antigens, including MNSs, RHCE, Kidd, Duffy, and Diego, was predicted through genotype analysis and corroborated the existing literature. We identified individuals with rare phenotypes, including 369 (0.51%) with Fy(a-b+), 188 (0.26%) with Di(a+b-), and 16 (0.02%) with Jr(a-). Furthermore, we calculated the frequencies of individuals with extremely rare phenotypes, such as p (0.000004%), Kell-null (0.000310%), and Jk(a-b-) (0.000438%), based on allele frequency predictions. These findings offer valuable insights into the distribution of blood group antigens in the Korean population and have significant implications for enhancing the safety and efficiency of blood transfusion.

Systemic administration of clinical-grade multilineage-differentiating stress-enduring cells ameliorates hypoxic-ischemic brain injury in neonatal rats

Multilineage-differentiating stress-enduring (Muse) cells are endogenous reparative pluripotent stem cells present in the bone marrow, peripheral blood, and organ connective tissues. We assessed the homing and therapeutic effects of systemically administered nafimestrocel, a clinical-grade human Muse cell-based product, without immunosuppressants in a neonatal hypoxic-ischemic (HI) rat model. HI injury was induced on postnatal day 7 (P7) and was confirmed by T2-weighted magnetic resonance imaging on P10. HI rats received a single dose nafimestrocel (1 × 106 cells/body) or Hank's balanced salt solution (vehicle group) intravenously at either three days (on P10; M3 group) or seven days (on P14; M7 group) after HI insult. Radioisotope experiment demonstrated the homing of chromium-51-labeled nafimestrocel to the both cerebral hemispheres. The cylinder test (M3 and M7 groups) and open-field test (M7 group) showed significant amelioration of paralysis and hyperactivity at five weeks of age compared with those in the vehicle group. Nafimestrocel did not cause adverse events such as death or pathological changes in the lung at ten weeks in the both groups. Nafimestrocel attenuated the production of tumor necrosis factor-α and inducible nitric oxide synthase from activated cultured microglia in vitro. These results demonstrate the potential therapeutic benefits and safety of nafimestrocel.

Improved quantitative detection of biotin-labeled red blood cells by flow cytometry

BACKGROUND

Biotin-labeled red blood cells (BioRBC) can be tracked after transfusion, providing a convenient and safe way to measure RBC survival in vivo. RBC survival is of interest for determining optimal blood storage conditions and for assessing the impact of genetic and biologic variants in blood donors on the survival of transfused RBCs. Here we present an improved, platform-independent assay for quantifying biotin on BioRBC. This approach is also useful for detecting BioRBC in peripheral blood samples as rare events.

STUDY DESIGN AND METHODS

We optimized the signal-to-noise ratio of the detecting reagent (phycoerythrin-conjugated streptavidin [SA-PE]) by determining the SA-PE concentration yielding the greatest separation index between BioRBC and unlabeled RBCs. We calibrated the fluorescence intensity measurements to molecules of equivalent soluble fluorochrome (MESF), a quantitative metric of fluorochrome binding and therefore of biotin bound per RBC. We then characterized the limit of blank and limit of quantification (LoQ) for BioRBC labeled at different densities.

RESULTS

Biotin-labeled RBCs at sulfo-NHS-biotin concentrations of 3 to 30 μg/mL (27-271 nmol/mL RBCs) ranged from approximately 32,000 to 200,000 MESF/RBC. The LoQ ranged from one in 274,000 to one in 649,000, depending on biotin-labeling density.

CONCLUSION

Increased sensitivity to detect BioRBC may facilitate tracking over longer periods and/or reduction of the BioRBC dose. Total RBC-bound biotin dose has been shown to correlate with the likelihood of developing antibodies to BioRBC. Lowering the dose of labeled cells may help avoid this eventuality.

Biomarkers of metal toxicity in embryos in the general population

Background

With the development of industrialization, public exposure to toxic metals could occur everywhere, eventually affecting individuals’ reproductive systems and even embryos and leading to early pregnancy loss. The aim of the study was to determine the profile of toxic metal levels in pregnant women in the general population and to identify biomarkers for metal toxicity in embryos.

Methods

A case‐control study with pregnant women was conducted at Peking Union Medical College Hospital in 2016‐2018. Women who experienced spontaneous abortion within 12 weeks of gestation comprised the case group, and women with pregnancies showing fetal cardiac activity who requested an induced abortion almost simultaneously were included in the control group. Blood and urine specimen were tested for concentrations of cadmium, chromium, selenium, arsenic, and mercury.

Results

A total of 195 patients were enrolled, with 95 in the case group and 100 in the control group. Significant differences in gravidity, parity, history of miscarriage, mean blood cadmium levels, and mean urine chromium levels were present between the two groups (P1 = 0.013, P2 = 0.000, P3 = 0.000, P4 = 0.002, P5 = 0.046); the odds ratios in the spontaneous abortion with blood cadmium >0.4 µg/L, urine chromium >2 µg/L, gravity <3, parity <2, and history of miscarriage >1 compared with the induced abortion group were 1.26 (1.09, 1.85), 1.56 (1.23, 2.53), 1.39 (1.17, 1.98), 1.72 (1.21, 4.62), and 1.18 (1.06, 1.65), with P‐values of 0.003, 0.031, 0.003, 0.247, and 0.001, respectively.

Conclusion

Blood cadmium and urine chromium levels are two possible biomarkers of toxic metal embryotoxicity in the general population, which means that in the general population, blood cadmium >0.4 µg/L or urine chromium >2 µg/L might indicate an increased risk of spontaneous abortion.

Current good manufacturing practices-compliant manufacture and measurement of biotin-labeled red blood cells

BACKGROUND

Red blood cells (RBCs) can be labeled with N-hydroxysuccinimidobiotin (sulfo-NHS-biotin), which binds to cell surface proteins under aqueous conditions. Biotinylated RBCs can be safely infused and detected in peripheral blood samples using flow cytometry, using a fluorochrome-conjugated streptavidin (SA) detection reagent. Biotinylated RBCs have been used to track survival of transfused RBCs, and have applications in optimizing RBC storage and in understanding donor genetic, environmental and disease factors affecting RBC products.

METHODS

We have developed a closed-system, current good manufacturing practices (cGMP)-compliant procedure for biotinylation of RBCs and a quantitative flow cytometric assay to estimate the dose of cell-bound biotin delivered to the patient. Resulting products were characterized for variability, sterility, endotoxin, hemolysis, total dose of cell-bound biotin and stability.

RESULTS

The density of biotin-labeling increased as a log-linear function of sulfo-NHS-biotin-labeling concentration, with greater variability at lower concentrations. The upper estimates of biotin doses in the average product (mean RBC content = 5.55 × 10¹¹) were 9.8 and 73.0 µg for products labeled at 3 and 15 µg sulfo-NHS-biotin/mL of total reaction mixture (27 and 135 nmol/mL packed RBCs), respectively. All products were negative for bacterial and fungal growth at 14 days and were below the limit of endotoxin detection. Biotinylated RBCs were stable in vitro for up to 50 days after labeling.

DISCUSSION

We have validated a closed-system procedure for biotinylating RBCs for investigational use. A standard operating procedure is presented in sufficient detail for implementation in a cGMP-compliant cell-processing facility.

Rates of carbon monoxide elimination in males and females

The purpose of this study was to verify the previously reported shorter half‐time of elimination (t_½) of carbon monoxide (CO) in females compared to males. Seventeen healthy subjects (nine men) completed three sessions each, on separate days. For each session, subjects were exposed to CO to raise the carboxyhemoglobin percentage (COHb) to ~10%; then breathed in random order, either (a) 100% O₂ at poikilocapnia (no CO₂ added), or (b) hyperoxia while maintaining normocapnia using sequential gas delivery, or (c) voluntary hyperpnea at~4x the resting minute ventilation. We measured minute ventilation, hemoglobin concentration [Hb] and COHb at 5 min intervals. The half‐time of reduction of COHb (t_½) was calculated from serial blood samples. The total hemoglobin mass (Hb_TOT) was calculated from [Hb] and estimated blood volume from a nomogram based on gender, height, and weight. The t_½ in the females was consistently shorter than in males in all protocols. This relationship was sustained even after controlling for alveolar ventilation (P <0.05), with the largest differences in t_½ between the genders occurring at low alveolar ventilation rates. However, when t_½ was further normalized for Hb_TOT, there was no significant difference in t_½ between genders at alveolar ventilation rates between 4 and 40 L/min (P =0.24). We conclude that alveolar ventilation and Hb_TOT are sufficient to account for a major difference in CO clearance between genders under resting (nonexercising) conditions.

The rate of removal of carbon monoxide from the blood is different between males and females, and this difference is largely due to the difference in total hemoglobin mass between the genders and alveolar ventilation. If the hemoglobin concentration is normalized between the genders, and alveolar ventilation is similar between them, this gender difference is eliminated, and the carboxyhemoglobin decay is roughly equal between the genders.

Blood loss comparison during transurethral resection of prostate and high power GreenLight(™) laser therapy using isotopic measure of red blood cells volume

BACKGROUND

Transurethral resection of the prostate (TURP) remains the gold standard in the operative management of symptomatic benign prostatic hyperplasia (BPH). The main morbidity of TURP is bleeding, which leads to clot retention and blood transfusion. Newer techniques have appeared, and photovaporization of the prostate (PVP) with the GreenLight™ laser has been developed to reduce the morbidity of bladder outflow surgery. Isotopic measurements of total red cell volume and total blood volume (BV) are a recommended reference technique to evaluate bleeding occurring during endoscopic ablation of the prostate. Here, we compare blood loss during PVP and TURP using an isotopic method.

METHODS

Eighteen patients underwent PVP, and 20 patients underwent a TURP for symptomatic BPH by one surgeon. The two groups were comparable in demographic data; however, prostate volume was significantly higher in the PVP group. BV was measured pre- and postoperatively using the isotope technique.

RESULTS

The total BV was measured to have increased by 362 mL in PVP group compared with a loss of 315 mL in TURP group (p=0.001). The difference in total red cell volume increased by 148 mL in PVP group compared with a loss of 216 mL in TURP group (p=0.005).

CONCLUSIONS

Using the isotope method, we have shown a significant difference in postoperative blood loss between TURP and PVP. Our study is the first to use an isotopic method to measure the blood loss during PVP. This technique needs further standardization before being introduced into routine clinical practice.

Glucose-6-phosphate dehydrogenase deficiency: a historical perspective

Glucose-6-phosphate dehydrogenase deficiency serves as a prototype of the many human enzyme deficiencies that are now known. Since its discovery more than 50 years ago, the high prevalence of the defect and the easy accessibility of the cells that manifest it have made it a favorite tool of biochemists, epidemiologists, geneticists, and molecular biologists as well as clinicians. In this brief historical review, we trace the discovery of this defect, its clinical manifestations, detection, population genetics, and molecular biology.

Effect of intermedin/adrenomedullin-2 on venous tone in conscious rats

We investigated the effect of intermedin/adrenomedullin-2 (3 and 10 nmol/kg, i.v.), a member of the calcitonin gene-related peptide family, relative to the vehicle (0.9% NaCl) on mean circulatory filling pressure (index of venous tone) in conscious rats: intact (unblocked) or ganglionic blocked through treatment with mecamylamine (10 mg/kg, i.v.) and noradrenaline (4 microg/kg/min, i.v.). In intact rats, both doses of intermedin/adrenomedullin-2 reduced mean arterial pressure (-14+/-3, -30+/-3 mmHg), but did not alter mean circulatory filling pressure; the high dose also increased heart rate. In ganglionic-blocked rats, both doses decreased mean arterial pressure (-22+/-3, -46+/-5 mmHg) and the high dose also decreased mean circulatory filling pressure (-2.81+/-0.82 mmHg), but neither dose affected heart rate. The vehicle did not have any effects in any of the groups. In addition, intermedin/adrenomedullin-2 did not have any effect on blood volume in both intact and ganglion-blocked rats. The results show that intermedin/adrenomedullin-2 is a dilator of arterial resistance and capacitance vessels.

Role of endothelin ET(A)- and ET(B)-receptors in haemodynamic compensation following haemorrhage in anaesthetized rats

1. This study examined the role of endothelin ET(A) and ET(B) receptors on haemodynamic compensation following haemorrhage (-17.5 ml kg(-1)) in thiobutabarbitone-anaesthetized rats. Rats were divided into four groups (n=6 each): time-control, haemorrhage-control, haemorrhage after treatment with FR 139317 (ET(A)-receptor antagonist), and haemorrhage after treatment with BQ-788 (ET(B)-receptor antagonist). 2. In the time-control rats, there were no significant changes in any haemodynamics for the duration of the experiments. Relative to the time-control rats, rats given haemorrhage had reduced mean arterial pressure (MAP), cardiac output (CO) and mean circulatory filling pressure (MCFP), but increased systemic vascular resistance (R(SV)). Venous resistance (R(V)) was slightly (but insignificantly) reduced by haemorrhage. MAP, however, gradually returned towards baseline (-17+/-4 and -3+/-2 mmHg at 10 and 60 min after haemorrhage, respectively) as a result of a further increase in R(SV). 3. Pre-treatment with FR 139317 (i.v. 1 mg kg(-1), followed by 1 mg kg(-1) h(-1)) accentuated haemorrhage-induced hypotension through abolition of the increase in R(SV). FR 139317 did not modify haemorrhage-induced changes in CO, MCFP and R(V). 4. Pre-treatment of BQ-788 (3 mg kg(-1)) did not affect MAP or MCFP following haemorrhage; however, CO was lower, and R(SV) as well as R(V) were higher relative to the readings in the haemorrhaged-control rats. 5. These results show that following compensated haemorrhage, ET maintains arterial resistance and blood pressure via the activation of ET(A) but not ET(B) receptors.

Haemodynamic changes in the rat femur and tibia following femoral vein ligation

Interference with venous outflow from a limb to stimulate fracture repair and bone growth has a long history, and its beneficial effects have been confirmed by many experimental and clinical studies. With the development of fracture fixation systems, the therapeutic use of circulatory intervention became redundant. Recently, a venous tourniquet effect has been cited to explain the enhancement of bone healing observed after fracture fixation with the Aircast system. As bone appears to be altered by venous stasis, it is important to characterise the vascular perturbations leading to these changes. Previous studies have often given conflicting results. This study investigated the short and long term haemodynamic effects of femoral vein ligation. Changes in blood flow rate and blood volume in the distal femur and proximal tibia of the rat were examined at 6 h and 1, 3 and 7 d following unilateral femoral vein ligation, and at 8 and 16 wk. Blood flows and volumes were generally reduced in the ligated limb 6 h after femoral vein ligation. This initial depression was followed by a relative increase (comparing the ligated limb with the contralateral unoperated bone) in blood volume during the 1st week. A significant relative reduction in epiphyseal vascular space was observed after 16 wk. A sustained reduction of arterial input to whole femora and tibiae was present in the ligated limb throughout the investigation although, for the cancellous knee joint epiphysis of the tibia, a localised relative increase in flow was apparent during the 1st week, again comparing the ligated limb with the nonligated contralateral bone.(ABSTRACT TRUNCATED AT 250 WORDS)

Angiotensin II and catecholamines interaction in short-term low protein feeding

Renal and systemic hemodynamic responses to an alpha-adrenergic agonist (norepinephrine, NE) and an alpha-adrenergic antagonist (phentolamine, PHEN) were studied in weanling rats pair-fed isocaloric diets containing either normal (NP, 23%) or low (LP, 6%) protein. Mean arterial pressure (MAP) rose less with NE and fell more with PHEN in LP than in NP. Plasma NE and epinephrine (E; 46 +/- 5 and 51 +/- 4 ng/ml) were higher in LP than in NP (26 +/- 3 and 39 +/- 3 ng/ml). These could not be attributed to changes in red cell mass nor the volumes of plasma, extracellular, or interstitial fluid in LP versus NP. Plasma angiotensin II (Ang II), renin (PRA), and aldosterone (PA) were lower in LP than in NP. An increased number without changes in affinity of glomerular Ang II receptors was found in LP compared to NP, while alpha 1- and alpha 2-adrenergic receptors were down-regulated in LP as compared to NP without changes in affinity for the alpha 1 receptor but with an increase in renal alpha 2 receptor affinity. LP (vs. NP) decreased GFR and RPF, and increased renal vascular resistance (RVR). NE decreased RPF equally in NP versus LP but raised RVR approximately twofold in NP versus LP. PHEN decreased RPF and increased RVR less in LP than in NP. Moreover, PHEN increased renal renin content approximately seven-fold over the basal NP values. Exogenous Ang II increased RVR and lowered RPF more in LP than in NP. Enalapril abolished all the hemodynamic changes of LP and restored the systemic response to NE.(ABSTRACT TRUNCATED AT 250 WORDS)

Dual hemodynamic mechanisms for salt-induced hypertension in Dahl salt-sensitive rats

Cardiac output, blood volume, total peripheral resistance, and renal blood flow were measured in awake salt-sensitive and salt-resistant Dahl rats on normal rat chow (1% NaCl) and on high salt (8% NaCl) diets. Rats were studied after 4, 8, and 46 weeks on a 1% NaCl diet and after 4 and 8 weeks on an 8% NaCl diet. Salt-sensitive rats on 8% NaCl for 4 weeks developed systolic hypertension; by 8 weeks they developed greater systolic and also diastolic hypertension. Salt-resistant rats on 8% NaCl remained normotensive throughout the studies, although renal resistance decreased (p less than 0.05). At 4 weeks, hypertension in salt-sensitive rats on 8% NaCl was caused by increased blood volume and cardiac output (p less than 0.05), with normal total peripheral resistance. At 8 weeks, hypertension was due to increased total peripheral resistance (p less than 0.05); cardiac output was below normal despite persistent elevation of blood volume (p less than 0.05). Salt-sensitive rats on 1% NaCl for 46 weeks were hypertensive, with elevated total peripheral resistance (p less than 0.05); cardiac output decreased (p less than 0.05), whereas blood volume remained unchanged. Salt-resistant rats on 1% NaCl remained normotensive with no charges in hemodynamics. Salt-sensitive rats on 8% NaCl for 4 weeks had an increase in renal vascular resistance but no significant change in nonrenal resistance or total peripheral resistance. The increased total peripheral resistance in salt-sensitive rats on 8% NaCl for 8 weeks and on 1% NaCl for 46 weeks was a reflection of increases of both renal and nonrenal vascular resistance.(ABSTRACT TRUNCATED AT 250 WORDS)

Glucose metabolism in patients with Cushing's syndrome

Glucose intolerance, sometimes severe enough to cause frank diabetes mellitus, is a frequent feature of Cushing's syndrome. The primary cause of the hyperglycaemia, whether due to glucose over-production or under-utilization, remains unresolved. We therefore measured glucose turnover using an intravenous bolus of 3-3H glucose in 14 normoglycaemic patients with Cushing's syndrome and 14 control subjects. Seven of the patients with Cushing's syndrome were also restudied post-operatively. Plasma glucose concentrations were similar in all three groups whereas glucose metabolic clearance rate (MCR) (1.80 +/- 0.06 ml/min/kg) and glucose turnover rate (9.09 +/- 0.36 mumol/min/kg) were significantly reduced in patients with Cushing's syndrome compared to normal subjects (2.21 +/- 0.1; P less than 0.001; 10.90 +/- 0.50; P less than 0.01) and rose post-operatively to normal values (2.35 +/- 0.14 ml/min/kg; 11.07 +/- 0.48 mumol/min/kg). We conclude from these results that the hyperglycaemia sometimes found in Cushing's syndrome may be primarily due to decreased utilization rather than increased glucose production.

Body composition in Chinese subjects: comparison with data from North America

A multiple tracer dilution method measuring total body water, extracellular water, plasma volume, and red cell volume was used to study body composition. Healthy Chinese subjects were compared to a group of Chinese patients with various newly diagnosed gastrointestinal disorders scheduled for elective operation. Compositional data obtained from these groups showed no significant differences in compartmentalization, suggesting absence of major changes during the early stages of certain gastrointestinal diseases. In addition, healthy Chinese subjects were compared to a group of healthy Americans previously evaluated by similar dilutional methods. In males, body weight (kg) differed considerably (Chinese = 62.1 +/- 2.0 versus American = 72.5 +/- 4.1, p less than 0.02) and could be explained by alterations in body fat (Chinese = 12.4 +/- 1.3 versus American = 19.2 +/- 2.2, p less than 0.02) and extracellular water (Chinese = 14.4 +/- 0.5 versus American = 16.8 +/- 0.8, p less than 0.02). Functional tissue ("body cell mass") was similar in the 2 groups which suggested that Chinese have comparable body composition without an additional fat burden. The multiple tracer technique using deuterium oxide, sodium bromide, Evans dye, and Cr51 for body compositional assessment is accurate but expensive and laborious. Therefore, equally precise but more economical bedside methods are needed for routine compositional analysis.

Hb south Milwaukee [beta 105 (G7) Leu----Phe]: a newly-identified hemoglobin variant with high oxygen affinity

Fifteen individuals among four generations of a family of English ancestry demonstrated elevated hemoglobin levels accompanied by leftward-shifted whole blood oxygen equilibrium curves. Five of the affected family members have required phlebotomies for relief of symptoms attributable to erythrocytosis. An abnormal hemoglobin or globin chain could not be isolated, but 43% of the beta chains of the affected individuals contained a Leu----Phe substitution at position 105 (G7). Oxygen equilibrium curves demonstrated a normal Bohr effect but decreased cooperativity.

Diurnal variation in glucose and leucine metabolism in non-insulin-dependent diabetes

Glucose and leucine metabolism were investigated in 5 poorly controlled non-insulin-dependent diabetics (NIDDM) following an i.v. injection of 3-[3H]glucose and 1-[14C]leucine in the morning and evening. In the morning glucose concentration (11.2 +/- 0.8 mmol/l) (mean +/- SEM) and production rate (14.2 +/- 1.3 mumol/min/kg) were significantly greater (P less than 0.001, P less than 0.05) and glucose metabolic clearance rate (MCR) (1.3 +/- 0.2 ml/min/kg) significantly lower (P less than 0.05) than in a group of control subjects. Glucose concentration was lower in the evening (P less than 0.05) as a result of a decrease in glucose production rate (P less than 0.05). Leucine concentration and production rate were not significantly different from normal but leucine oxidation rate was increased (P less than 0.05). There was no diurnal variation in leucine metabolism. Since leucine production is a measure of protein breakdown, the higher morning glucose production rate was not due to an increased supply of gluconeogenic precursors from protein catabolism.

Salt-induced hypertension in Dahl salt-sensitive rats. Hemodynamics and renal responses

This study was performed with Dahl salt-sensitive (DS) and Dahl salt-resistant (DR) rats to detect differences in cardiovascular hemodynamics and renal responses that might be involved in initiating salt-induced hypertension in DS rats. The effects of 4 weeks of 8% NaCl diet were studied in conscious, male DR and DS rats in which vascular and urinary catheters had been previously implanted. Results were compared with those obtained from control groups of DR and DS rats on 4 weeks of 1% NaCl diet. DR rats on 8% salt diet did not develop hypertension, and cardiac output and blood volume were unchanged; glomerular filtration rate, urinary flow, sodium excretion, and plasma atrial natriuretic factor (ANF) increased. DS rats on 8% salt diet developed hypertension, and cardiac output and blood volume increased; glomerular filtration rate, urinary flow, and sodium excretion did not change, despite an increase in ANF. DS and DR rats on 1% NaCl diet were subjected to ANF infusion. After ANF infusion DR rats had a decreased blood volume and an increased glomerular filtration rate, urinary flow, and sodium excretion; DS rats showed no significant changes in blood volume, glomerular filtration rate, urinary flow, or sodium excretion. ANF caused vasodilation in all regions studied in DR rats; DS rats showed vasodilation in all regions except the kidney. After acute volume expansion, although both DR and DS rats responded by an increase in cardiac output, only DS rats developed prolonged hypertension. This finding suggests an inadequate vasodilatory mechanism in DS rats. In response to acute volume expansion, renal resistance decreased in DR rats but not in DS rats. It is concluded that the primary hemodynamic disturbance in DS rats with salt-induced hypertension is an increase in cardiac output caused by blood volume expansion in the absence of any vasodilation. Comparison of the responses of DS and DR rats to high salt diets, ANF infusion, and acute volume expansion indicates that the salt-induced hypertension in DS rats is initiated by a diminished renal response to ANF.

Proinflammatory effects of local abdominal irradiation on rat gastrointestinal tract

Although the role of inflammatory processes in the genesis of late changes in the gastrointestinal tract following exposure to ionizing irradiation has been extensively studied, few studies have concentrated on the presence of an acute inflammatory response in the period immediately following radiation. We therefore examined, in rats, whether the local application of 10 Gy cobalt-60 irradiation to the abdomen led to changes in the gut within the first 24 hr that were consistent with an acute inflammatory response. In stomach, small intestine, and colon, local irradiation led to a significant increase in the accumulation of plasma within the tissue by 4-8 hr following irradiation. This increase in tissue plasma volume, indicative of an increased microvascular permeability, was then sustained until the end of the 24-hr assessment period in all tissues examined. Concurrent with this was a consistent transient increase in tissue red blood cell volume, suggestive of vasodilation. Of particular note, a significant increase in the number of mucosal neutrophils was also observed between 2 and 12 hr following irradiation. This elevation in mucosal neutrophils was particularly marked in the pericryptal or deep mucosal regions of small intestine and colon and consistently preceded the vasodilation and enhanced permeability. Furthermore these pathophysiological alterations occurred at a time when histological changes in the mucosa consistent with an impaired mucosal microcirculation (ie, edema of the lamina propria and subepithelial bleb formation) were present. These results support the hypothesis that an inflammatory response occurs in the gut during the first 24 hr following abdominal irradiation. Such changes may then further exacerbate the damage initiated by the ionizing radiation.

Red blood cell volume (RBCV) and blood volume (BV) in male albino (NZW) rabbits with 99mTc

Estimation of red blood cell volume (RBCV) and blood volume (BV) in experimental animals is important for studies concerning pharmaceutical distribution. In this study RBCV was measured, using 99mTc, in 64 male albino New Zealand rabbits with a body weight (BW) of 3.12 +/- 0.37 (SD) kg. The packed cell volume (PCV) was 38.17 +/- 2.37% (SD), the hematocrit (Hct) of the venous blood sample, corrected for trapped plasma, was PCV x 0.97 and the somatic hematocrit (Ho) was calculated as 0.89 x Hct. RBCV was measured using the pretinning method and the BV was calculated according to the formula BV = RBCV x 100/Ho. Labeling efficiency was 96.4% +/- 3.8% (SD). The RBCV was found to be 18.52 +/- 1.96 (SD) mL/kg (BW) and BV 56.12 +/- 4.82 (SD)mL/kg (BW). The correlation of the RBCV and BV to BW is given by the formulae: RBCV = 66.754 ln(BW(g)) - 478.702 (r2 = 0.624, P less than 0.001) and BV = -47.587 + 197.342 ln(BWkg) (r2 = 0.72, P less than 0.001). The 99mTc results do not differ significantly from those of the standard 51Cr procedure, but the 99mTc labeling method permits repetitive measurements at shorter intervals compared to 51Cr.

Changes in erythropoiesis due to radiation or chemotherapy as studied by flow cytometric determination of peripheral blood reticulocytes

Flow cytometric determination of time dependent changes of numbers of reticulocytes in peripheral blood were investigated as a parameter for changes in erythropoiesis induced by radiation- or chemotherapy. Rats irradiated or treated with drugs (such as e.g. cyclophosphamide 100 mg/kg, vincristin 0.2 mg/kg, or mitomycin C 1.0 mg/kg) showed clear changes in erythropoietic activity. Reticulocyte numbers decreased rapidly until day 3-4 after treatment; this period was followed by a gradual increase and normal control values were seen at day 8-11. Radiation effects of doses as low 0.5 Gy could be detected in such a way. Similar studies were performed with patients with ovarian tumors treated with cis-platinum, a drug that may cause non-immune haemolysis. During prolonged treatment some patients showed increasing numbers of reticulocytes, measured at the first day of each hospitalization period, whereas leucocyte and platelet counts stayed more or less constant. Increasing numbers of reticulocytes generally indicates stimulation of erythropoietic activity of the bone marrow (due to increased blood loss); in this study increasing numbers often preceeded a decrease in hemoglobin values later on. Flow cytometric analysis of reticulocytes is therefore a potentially useful tool to detect changes in erythropoiesis, and considered more sensitive for the early recognition of patients that develop anemia, than hemoglobin measurements only.

The effect of metabolic control on leucine metabolism in type 1 (insulin-dependent) diabetic patients

Leucine production rate, metabolic clearance rate and oxidation rate were measured in 10 Type 1 (insulin-dependent) diabetic patients after 24 h insulin withdrawal, conventional insulin therapy and an overnight insulin infusion to maintain normoglycaemia, and in 10 control subjects. In the insulin-withdrawn patients, leucine concentration (259 +/- 17 mumol/l), production rate (2.65 +/- 0.29 mumol . min-1 . kg-1) and oxidation rate (0.69 +/- 0.10 mumol . min-1 . kg-1) were significantly greater (p less than 0.001; p less than 0.05; p less than 0.005 respectively) than corresponding values in control subjects (127 +/- 6; 1.81 +/- 0.12; 0.19 +/- 0.02). Following conventional insulin therapy, leucine concentration (162 +/- 12 mumol/l) and oxidation rate (0.43 +/- 0.05 mumol . min-1 . kg-1) were lower than after insulin withdrawal but were still significantly greater than in control subjects (p less than 0.05; p less than 0.005). Although leucine concentration, production rate and metabolic clearance rate were normal after an overnight insulin infusion, leucine oxidation rate was still greater than normal (0.34 +/- 0.06 mumol . min-1 . kg-1; p less than 0.05). These results suggest that increased leucine concentration in insulin deficiency is due to elevated leucine production rate caused by increased proteolysis, and that leucine concentration is restored to normal by insulin treatment.

A study of the renin-angiotensin system and the blood volume in the nephrotic syndrome

The plasma renin activity (PRA), plasma aldosterone level, and blood volume were studied in 12 patients with idiopathic nephrotic syndrome. As a whole, the patients with the nephrotic syndrome showed significant elevations of the PRA and plasma aldosterone but not in blood volume compared to the normal controls. Six patients who had a larger blood volume than the control group had decreased PRA, while the other 6 patients who had a smaller blood volume than the control group had an increased PRA. Also noted was that there was no histopathological difference of kidney diseases between the patients with increased blood volume and decreased blood volume. Though there was no correlation between serum albumin, PRA, and plasma aldosterone levels, there was a tendency of increased blood volume as serum albumin decreased.

Chromium bond detection in isolated erythrocytes: a new principle of biological monitoring of exposure to hexavalent chromium

Internal stress to chromium is only relevant in occupational medicine if it is due to the handling of hexavalent chromium. Cr(VI) ions, after uptake by inhalation or percutaneously are carried in the blood plasma and penetrate--depending on the concentration--into the erythrocytes. Due to the intracellular reduction to Cr(III) and the concurrent intracellular protein binding, the erythrocytes represent an easily accessible target organ for quantitative chromium determination after occupational exposure to Cr(VI) compounds. The results of an earlier experimental study indicate that human plasma too is capable of spontaneous reduction of Cr(VI) ions of up to 2 ppm to Cr(III). This plasma reduction capacity (PRC) can be increased and accelerated considerably by adding ascorbic acid (AA). These findings were supported in this investigation by proving a decreased binding of Cr(VI) inside the erythrocytes under the effect of AA. This leads to the assumption that only those Cr(VI) concentrations can penetrate the membrane of the erythrocytes and enter the cell which either come into contact with the membrane during the reduction process or exceed this limit concentration of 2 ppm. Only in these two instances can corresponding chromium findings be analyzed in isolated and washed erythrocytes. These results are compared with those obtained by conventional methods, such as Cr determination in the blood and/or urine. Our findings indicate that a single determination of chromium concentration in the erythrocytes will permit the monitoring of critical cases of Cr(VI) exposure. This is a new type of biological monitoring in the sense of a condensed longitudinal study, in order to find out whether threshold concentrations have been respected over a given period.

Role of the low density lipoprotein receptor in penetration of low density lipoprotein into rabbit aortic wall

The present study was designed to determine whether binding of low density lipoprotein (LDL) to endothelial LDL receptors contributes significantly to the penetration of LDL into the normal rabbit aorta. Initial flux rate was used as a measure of uptake of LDL. Reductive methylation of LDL is known to block its recognition by the LDL receptor. Therefore, the difference in flux rates of native LDL and reductively methylated LDL (methyl-LDL) was assumed to represent the receptor-dependent uptake. Native LDL and methyl-LDL were labeled with different isotopes (125I or 131I) and both were injected simultaneously into the same rabbit. After 30 to 60 minutes, trichloroacetic acid-precipitable counts were determined in aortic specimens. The initial flux rates, expressed as plasma clearance (nl/g/hr), were 1787 for native LDL and 1924 for methyl-LDL. The difference was not significant, which suggests that the flux of LDL into the aorta is not significantly dependent upon, or regulated by, endothelial LDL receptors, but is mediated by other mechanisms.

Therapeutic trial of plasma exchange in osteosclerotic myeloma associated with the POEMS syndrome

A patient with osteosclerotic myeloma and POEMS syndrome, unresponsive to pulse prednisone and melphalan therapy, was admitted to the hospital for a trial of plasma exchange therapy. The presentation included IgG lambda monoclonal gammopathy, peripheral neuropathy, hepatosplenomegaly, hyperpigmentation and thickening of the skin, edema, and tense ascites. Laboratory tests confirmed hypothyroidism, hypogonadism, and adrenal insufficiency. Six exchange procedures failed to affect the clinical course, and the patient died. Greater-than-one-plasma-volume exchanges (patient's measured plasma volume, 2,703 cc) were performed. When IgG and cholesterol removal were compared to the predicted removal, based on the volume of plasma removed, significantly less reduction in concentration than predicted was measured. IgG concentrations increased postapheresis and, at 2 weeks, three-fourths of the removed IgG had reaccumulated. A reduced efficiency of removal of both IgG and cholesterol can be explained by postulating increased vascular permeability with free exchange of soluble substances from one compartment to another. If an abnormal product is produced by the disease and is responsible for the clinical syndrome, a more intensive schedule of plasma exchange therapy may be needed to achieve a sustained depletion of the responsible soluble substance. Alternatively, neither increased vascular permeability or the clinical manifestations are responsive to removal of a soluble substance or are caused by a soluble substance produced by the malignancy.