Genotoxicity assessment in HepaRG™ cells as a new approach methodology follow up to a positive response in the human TK6 cell micronucleus assay: Naphthalene case study

We are evaluating the use of metabolically competent HepaRG™ cells combined with CometChip® for DNA damage and the micronucleus (MN) assay as a New Approach Methodology (NAM) alternative to animals for follow up genotoxicity assessment to in vitro positive genotoxic response. Naphthalene is genotoxic in human TK6 cells inducing a nonlinear dose-response for the induction of micronuclei in the presence of rat liver S9. of naphthalene. In HepaRG™ cells, naphthalene genotoxicity was assessed using either 6 (CometChip™) or 12 concentrations of naphthalene (MN assay) with the top dose used for assessment of genotoxicity for the Comet and MN assay was 1.25 and 1.74 mM respectively, corresponding to approximately 45% cell survival. In contrast to human TK6 cell with S9, naphthalene was not genotoxic in either the HepaRG™ MN assay or the Comet assay using CometChip®. The lack of genotoxicity in both the MN and comet assays in HepaRG™ cells is likely due to Phase II enzymes removing phenols preventing further bioactivation to quinones and efficient detoxication of naphthalene quinones or epoxides by glutathione conjugation. In contrast to CYP450 mediated metabolism, these Phase II enzymes are inactive in rat liver S9 due to lack of appropriate cofactors causing a positive genotoxic response. Rat liver S9-derived BMD10 over-predicts naphthalene genotoxicity when compared to the negative genotoxic response observed in HepaRG™ cells. Metabolically competent hepatocyte models like HepaRG™ cells should be considered as human-relevant NAMs for use genotoxicity assessments to reduce reliance on rodents.

The common indoor air pollutant α-pinene is metabolized to a genotoxic metabolite α-pinene oxide

1. α-Pinene caused a concentration-responsive increase in bladder hyperplasia and decrease in sperm counts in rodents following inhalation exposure. Additionally, it formed a prospective reactive metabolite, α-pinene oxide.2. To provide human relevant context for data generated in animal models and explore potential mechanism, we undertook studies to investigate the metabolism of α-pinene to α-pinene oxide and mutagenicity of α-pinene and α-pinene oxide.3. α-Pinene oxide was formed in rat and human microsomes and hepatocytes with some species differences. Based on area under the concentration versus time curves, the formation of α-pinene oxide was up to 4-fold higher in rats than in humans.4. While rat microsomes cleared α-pinene oxide faster than human microsomes, the clearance of α-pinene oxide in hepatocytes was similar between species.5. α-Pinene was not mutagenic with or without induced rat liver S9 in Salmonella typhimurium or Escherichia coli when tested up to 10,000 μg/plate while α-pinene oxide was mutagenic at ≥25 μg/plate.6. α-Pinene was metabolized to α-pinene oxide under the conditions of the bacterial mutation assay although the concentration was approximately 3-fold lower than the lowest α-pinene oxide concentration that was positive in the assay, potentially explaining the lack of mutagenicity observed with α-pinene.

Sensitive CometChip assay for screening potentially carcinogenic DNA adducts by trapping DNA repair intermediates

Genotoxicity testing is critical for predicting adverse effects of pharmaceutical, industrial, and environmental chemicals. The alkaline comet assay is an established method for detecting DNA strand breaks, however, the assay does not detect potentially carcinogenic bulky adducts that can arise when metabolic enzymes convert pro-carcinogens into a highly DNA reactive products. To overcome this, we use DNA synthesis inhibitors (hydroxyurea and 1-β-d-arabinofuranosyl cytosine) to trap single strand breaks that are formed during nucleotide excision repair, which primarily removes bulky lesions. In this way, comet-undetectable bulky lesions are converted into comet-detectable single strand breaks. Moreover, we use HepaRG™ cells to recapitulate in vivo metabolic capacity, and leverage the CometChip platform (a higher throughput more sensitive comet assay) to create the 'HepaCometChip', enabling the detection of bulky genotoxic lesions that are missed by current genotoxicity screens. The HepaCometChip thus provides a broadly effective approach for detection of bulky DNA adducts.

Comprehensive evaluation of the flavonol anti-oxidants, alpha-glycosyl isoquercitrin and isoquercitrin, for genotoxic potential

Quercetin and its glycosides possess potential benefits to human health. Several flavonols are available to consumers as dietary supplements, promoted as anti-oxidants; however, incorporation of natural quercetin glycosides into food and beverage products has been limited by poor miscibility in water. Enzymatic conjugation of multiple glucose moieties to isoquercitrin to produce alpha-glycosyl isoquercitrin (AGIQ) enhances solubility and bioavailability. AGIQ is used in Japan as a food additive and has been granted generally recognized as safe (GRAS) status. However, although substantial genotoxicity data exist for quercetin, there is very little available data for AGIQ and isoquercitrin. To support expanded global marketing of food products containing AGIQ, comprehensive testing of genotoxic potential of AGIQ and isoquercitrin was conducted according to current regulatory test guidelines. Both chemicals tested positive in bacterial reverse mutation assays, and exposure to isoquercitrin resulted in chromosomal aberrations in CHO-WBL cells. All other in vitro mammalian micronucleus and chromosomal aberration assays, micronucleus and comet assays in male and female B6C3F1 mice and Sprague Dawley rats, and Muta™ Mouse mutation assays evaluating multiple potential target tissues, were negative for both chemicals. These results supplement existing toxicity data to further support the safe use of AGIQ in food and beverage products.

Genetic and rat toxicity studies of cyclodextrin glucanotransferase

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Bacterial cyclodextrin glucanotransferase (CGTase) is used to produce a water soluble form of glycosylated isoquercitrin.

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Genotoxicity battery on CGTase and sodium sulfate negative for mutations and DNA damage.

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No evidence of systemic toxicity in 90-day rat toxicity study of CGTase.

Introduction

Microbiologically derived cyclodextrin glucanotransferase (CGTase) is used commercially as a processing agent in manufacture of food, pharmaceuticals, and cosmetics. Its toxic potential was evaluated in anticipation of use in the production of alpha-glycosyl isoquercitrin, a water-soluble form of quercetin.

Methods

Following OECD guidelines, CGTase, produced by Bacillus pseudalcaliphilus DK-1139, was evaluated in a genotoxicity battery consisting of a bacterial reverse mutation assay, an in vitro micronucleus (MN) assay and MN and comet assays using B6C3F1 male and female mice. These same genotoxicity assays were also conducted for sodium sulfate, a contaminant of CGTase preparation. In a 90-day Sprague Dawley rat toxicity study, CGTase was administered by gavage in water at daily doses of 0, 250, 500, and 1000 mg/kg/day.

Results

CGTase did not induce mutations with or without metabolic activation in the bacterial reverse mutation assay. Formation of micronuclei was not induced in either in vitro or in vivo MN assays with or without metabolic activation. No induction of DNA damage was detected in male or female mouse liver, stomach, or duodenum in the comet assay. Sodium sulfate also tested negative in these same genotoxicity assays. In the 90-day repeated dose rat study there were no treatment-related adverse clinical or pathological findings.

Conclusion

The genotoxicity assays and repeated dose toxicity study support the safe use of CGTase in production of alpha-glycosyl isoquercitrin.

Genotoxicity evaluation of the flavonoid, myricitrin, and its aglycone, myricetin

Myricitrin, a flavonoid extracted from the fruit, leaves, and bark of Chinese bayberry (Myrica rubra SIEBOLD), is currently used as a flavor modifier in snack foods, dairy products, and beverages in Japan. Myricitrin is converted to myricetin by intestinal microflora; myricetin also occurs ubiquitously in plants and is consumed in fruits, vegetables, and beverages. The genotoxic potential of myricitrin and myricetin was evaluated in anticipation of worldwide marketing of food products containing myricitrin. In a bacterial reverse mutation assay, myricetin tested positive for frameshift mutations under metabolic activation conditions whereas myricitrin tested negative for mutagenic potential. Both myricitrin and myricetin induced micronuclei formation in human TK6 lymphoblastoid cells under conditions lacking metabolic activation; however, the negative response observed in the presence of metabolic activation suggests that rat liver S9 homogenate may detoxify reactive metabolites of these chemicals in mammalian cells. In 3-day combined micronucleus/Comet assays using male and female B6C3F1 mice, no induction of micronuclei was observed in peripheral blood, or conclusive evidence of damage detected in the liver, glandular stomach, or duodenum following exposure to myricitrin or myricetin. Our studies did not reveal evidence of genotoxic potential of myricitrin in vivo, supporting its safe use in food and beverages.

Nanosize titanium dioxide stimulates reactive oxygen species in brain microglia and damages neurons in vitro

BACKGROUND

Titanium dioxide is a widely used nanomaterial whose photo-reactivity suggests that it could damage biological targets (e.g., brain) through oxidative stress (OS).

OBJECTIVES

Brain cultures of immortalized mouse microglia (BV2), rat dopaminergic (DA) neurons (N27), and primary cultures of embryonic rat striatum, were exposed to Degussa P25, a commercially available TiO(2) nanomaterial. Physical properties of P25 were measured under conditions that paralleled biological measures.

FINDINGS

P25 rapidly aggregated in physiological buffer (800-1,900 nm; 25 degrees C) and exposure media (approximately 330 nm; 37 degrees C), and maintained a negative zeta potential in both buffer (-12.2 +/- 1.6 mV) and media (-9.1 +/- 1.2 mV). BV2 microglia exposed to P25 (2.5-120 ppm) responded with an immediate and prolonged release of reactive oxygen species (ROS). Hoechst nuclear stain was reduced after 24-hr (>or=100 ppm) and 48-hr (>or=2.5 ppm) exposure. Microarray analysis on P25-exposed BV2 microglia indicated up-regulation of inflammatory, apoptotic, and cell cycling pathways and down-regulation of energy metabolism. P25 (2.5-120 ppm) stimulated increases of intracellular ATP and caspase 3/7 activity in isolated N27 neurons (24-48 hr) but did not produce cytotoxicity after 72-hr exposure. Primary cultures of rat striatum exposed to P25 (5 ppm) showed a reduction of immunohistochemically stained neurons and microscopic evidence of neuronal apoptosis after 6-hr exposure. These findings indicate that P25 stimulates ROS in BV2 microglia and is nontoxic to isolated N27 neurons. However, P25 rapidly damages neurons at low concentrations in complex brain cultures, plausibly though microglial generated ROS.

Electrophilic chemistry of thia-PAHs: stable carbocations (NMR and DFT), S-alkylated onium salts, model electrophilic substitutions (nitration and bromination), and mutagenicity assay

First examples of stable carbocations are reported from several classes of thia-PAHs with four fused rings, namely, benzo[b]naphtho[2,1-d]thiophene (1) and its 3-methoxy derivative (2), phenanthro[4,3-b]thiophene (3) and its 7-methoxy (4), 10-methoxy (5), and 9-methoxy (6) derivatives, phenanthro[3,4-b]thiophene (7) and its 7-methoxy (8) and 9-methoxy (9) derivatives, and 3-methoxybenzo[b]naphtha[1,2-d]thiophene (11). In several cases, the resulting carbocations were also studied by GIAO-DFT. Charge delocalization modes in the resulting carbocations were probed. A series of S-alkylated onium tetrafluoroborates, namely, 1Me+, 1Et+, 2Et+, and 7Me+ (from 1, 2, and 7), 10Me+ and 10Et+ (from benzo[b]naphtha[1,2-d]thiophene 10), 12Me+ and 12Et+ (from phenanthro[3,2-b][1]benzothiophene 12), 13Me+ (from 3-methoxyphenanthro[3,2-b]benzothiophene 13), 14Me+ (from phenanthro[4,3-b][1]benzothiophene 14), and 15Me+ (from 3-methoxyphenanthro[4,3-b][1]benzothiophene 15), were synthesized. PAH-sulfonium salts 1Me+, 1Et+, 10Me+, 10Et+, 12Me+, and 14Me+ proved to be efficient akylating agents toward model nitrogen nucleophile receptors (imidazole and azaindole). Facile transalkylation to model nucleophiles (including guanine) is also supported by favorable reaction energies computed by DFT. Ring opening energies in thia-PAH-epoxides from 1, 3, and 7 and charge delocalization modes in the resulting carbocations were also evaluated. The four-ring-fused thia-PAHs 1, 2, 3, 4, 5, 7, 8, and 11 are effectively nitrated under extremely mild conditions. Nitration regioselectivity corresponds closely to protonation under stable ion conditions. Bromination of 4 and 6 is also reported. Comparative mutagenicity assays (Ames test) were performed on 1 versus 1NO2, 5 versus 5NO2, and 11 versus 11NO2. Compound 5NO2 was found to be a potent direct acting mutagen.

Adverse outcome with delay in identification of catatonia in elderly patients

All three patients to show catatonia at a teaching veterans' hospital over a 1-year period were over 60 years old. Each experienced delays of 2-5 months in identification of catatonia and adverse events attributable to the delay (e.g., pulmonary embolus, physical restraint, pneumonia, mislabeling as "advanced dementia," Do Not Resuscitate orders, and death). These outcomes suggest that geriatric patients with unrecognized catatonia are at high risk for major adverse events.

Quality of life outcomes of saquinavir, zalcitabine and combination saquinavir plus zalcitabine therapy for adults with advanced HIV infection with CD4 counts between 50 and 300 cells/mm3

BACKGROUND

Benefits in patient health-related quality of life (HRQL) have not yet been demonstrated for combination antiretroviral therapy with protease inhibitors and nucleoside analogues. This double-blind study evaluated zalcitabine or saquinavir monotherapy and combination saquinavir plus zalcitabine therapy on HROL of human immunodeficiency virus (HIV)-infected adults.

METHODS

940 HIV-infected patients (CD4 counts 50-300 cells/mm3) who had discontinued zidovudine therapy (for intolerance or treatment failure) were randomized to one of three regimens: zalcitabine 0.75 mg every 8 h; saquinavir 600 mg every 8 h; or combination zalcitabine 0.75 mg plus saquinavir 600 mg every 8 hours. HRQL was measured at baseline, 24 and 48 weeks using the Medical Outcome Study HIV Health Survey (MOS-HIV). The primary endpoints were the physical and mental health summary scores (PHS; MHS) of the MOS-HIV as well as a global visual analogue scale (VAS) score.

RESULTS

After 24 weeks, the zalcitabine-treated patients demonstrated significantly greater decreases in PHS scores (-4.4 +/- 0.6; saquinavir: -1.3 +/- 0.6; zalcitabine plus saquinavir: -1.7 +/- 0.6; P < 0.0001) and MHS scores (-2.2 +/- 0.5; saquinavir: -1.0 +/- 0.5; zalcitabine plus saquinavir: -0.5 +/- 0.5; P = 0.032) compared to saquinavir and zalcitabine plus saquinavir treated patients. No differences were observed on the VAS (P = 0.172). Nine of 10 MOS-HIV subscales demonstrated results consistent with the primary endpoints. After 48 weeks, a statistically significant difference between the saquinavir-treated groups and the zalcitabine monotherapy group was observed for PHS scores (zalcitabine: -5.8 +/- 0.6; saquinavir: -4.1 +/- 0.6; zalcitabine plus saquinavir: -3.5 +/- 0.6; P = 0.014).

CONCLUSIONS

Saquinavir monotherapy and combination saquinavir plus zalcitabine demonstrated a benefit in HRQL relative to zalcitabine monotherapy in patients with prior zidovudine therapy. The HRQL findings are concordant with improved survival and reduced clinical progression of HIV infection found in this study.

Resuscitation considerations to prevent pressure ulcers in trauma patients

The success of a trauma resuscitation is often measured in short-term patient outcomes. To be a true success, the patient should also be protected from long-term problems that are easily preventable. Skin pressure ulcers are a real threat to trauma patients who are immobilized. Nurses involved in the initial care of these patients should be aware of the common causes of skin breakdown and how to prevent it.

Hypofrontal symptoms from olanzapine: a case report

Olanzapine acutely induced disabling hypofrontal symptoms in a 31-year-old male. This occurred after 13 years of exposure to typical neuroleptics without such symptoms. Presumably, hypofrontal symptoms should limit the dose of atypical neuroleptics in some patients. Milder expressions of hypofrontal symptoms should be more common.

False-Positive Ethylene Glycol Levels in Patients With Diabetic Ketoacidosis

OBJECTIVE

To describe two patients with diabetic ketoacidosis and positive ethylene glycol levels and to call attention to the possibility of a false-positive ethylene glycol determination in patients with ketoacidosis.

METHODS

Clinical manifestations and laboratory tests in the two patients were summarized. Serum specimens for both patients were analyzed for ethylene glycol, serum ketones, glucose, osmolality, pH, and electrolytes.

RESULTS

Respective laboratory findings in our two patients were as follows: serum glucose levels, 56.4 and 45.7 mmol/L; serum acetone, positive in 1:80 and 1:128 dilution; serum osmolality, 366 and 377 mmol/kg; pH, 6.9 and 7.2; and ethylene glycol, 3.46 and 2.45 mmol/L.

CONCLUSION

Neither of these two elderly women had ingested ethylene glycol; nevertheless, both had positive results for ethylene glycol on a blood toxicology screen. Review of the literature demonstrates that false-positive ethylene glycol levels can be detected in patients with ketoacidosis. This information is documented in this report and should alert practicing physicians to such a possibility.

Blood pressure control and erythrocytosis in rats: theory and observations

We compared some of our latest experiments on blood pressure control and erythrocytosis in spontaneously hypertensive rats with Gaar's computer-simulated studies, which suggest that erythrocytosis is a key to understanding the hemodynamic changes in hypertension. We tested two of Gaar's several predictions: (i) peripheral vascular resistance decreases when the feedback control of erythrocytosis is blocked and (ii) in primary hypertension, blood volume is increased slightly. We also studied the interrelation of systolic blood pressure and plasma renin substrate in spontaneously hypertensive rats, and the effect of diet on renin, blood pressure, and erythrocytosis. Our data showed that (i) on a percentage basis the renin system supports blood pressure essentially in the same manner in normal and hypertensive rats, (ii) peripheral vascular resistance decreased when erythrocytosis was partially blocked by feeding a low-iron diet, (iii) blood volume was similar in normal and hypertensive rats, and (iv) dextrin stimulates plasma renin, packed cell volume, and blood pressure in hypertensive rats. We conclude that blood pressure and erythrocytosis are interrelated, that the combined data of stimulated and experimental studies support the notion that primary hypertension is a blood-vessel adaptation in response to a renal energy need that may require additional oxygen.

Unintentional injury death rates in rural Appalachia

Rural unintentional injury (UI) death rates are higher than rates for urban regions. Our trauma center serves 49 rural Appalachian (AP) counties in a 120-county rural state. We investigated the impact of prehospital and hospital resources on UI death rates in our referral area. Age-adjusted and average age- and sex-specific UI death rates from 1979-1985 were compared among 49 rural AP counties, the 71 non-Appalachian (NAP) counties, and the United States. Counties were grouped for comparisons by level of prehospital care (Advanced Life Support [ALS] vs. Basic Life Support [BLS]) and by presence (H) or absence (NH) of a hospital. Death rates were calculated using data from the 1980 population census, the National Center for Health Statistics (NCHS), and state vital statistics. Within AP, all 49 counties have ambulance service. Only 9/49 (18%) have ALS service and 13/49 (26%) have no hospital. Age-specific AP rates were higher than NAP and US rates in the 25-44 and 45-64 year age groups. AP death rates were highest for BLS and NH counties across all age groups. Rural UI death rates in the region remain unacceptably high. The reason(s) that AP death rates exceed the NAP rates is uncertain. ALS service and an available hospital were associated with lower death rates. We propose both educational and epidemiologic programs to better identify and define additional problems.

Concurrent focal segmental glomerulosclerosis and membranous nephropathy

Focal segmental glomerulosclerosis and membranous glomerulonephropathy are two entities that may result in the nephrotic syndrome. Two young women exhibited concurrent focal segmental glomerulosclerosis and focal segmental membranous nephropathy on renal biopsy. Although the lesions were severe, both patients had asymptomatic proteinuria, normal renal function, and a benign clinical course. The concurrence of these glomerulopathies may portend a more benign clinical course than expected for a patient presenting with either lesion alone.

Duration of ECT-induced tachycardia as a measure of seizure length

The duration of ECT-induced tachycardia in 203 seizures of 28 patients was measured. Tachycardia duration was easily determined; it correlated highly with both motor (cuffed arm) and EEG seizure estimates.

Prolactin levels after bilateral and unilateral ECT

Serial post-ictal serum prolactin levels were obtained over a period of one hour after bilateral or unilateral electroconvulsive therapy (ECT) in six patients. Bilateral ECT yielded significantly higher mean post-ictal prolactin levels than unilateral ECT at the 15, 20, 30 and 60 minute sampling times. These findings demonstrate a greater hypothalamic-stimulating effect of bilateral than unilateral ECT, and may explain the reported therapeutic advantage of bilateral over unilateral ECT in the treatment of patients with melancholia.

Predicting success of intensive dialysis in the treatment of uremic pericarditis

To identify predictors of the success or failure of daily intensive dialysis in uremic pericarditis, a retrospective examination was made of initial clinical, laboratory, and echocardiographic data in 97 patients using univariate and multivariate statistical analysis. In this group, 67 patients showed response to intensive dialysis, and 30 patients did not (22 required surgery and eight died). By univariate analysis, nine factors correlated with intensive dialysis failure (p less than 0.10): admission temperature over 102 degrees F, rales, admission blood pressure under 100 mm Hg, jugular venous distension, peritoneal dialysis treatment only because of severe hemodynamic instability, white blood cell count over 15,000/mm3, white blood cell count left shift, large effusion by echocardiography, and both anterior and posterior effusion by echocardiography. Echocardiographic left ventricular size and function were not useful predictors of success or failure; there was no difference in response to hemodialysis in patients with pericarditis before dialysis (69 percent) versus patients with pericarditis during a maintenance program (67 percent). By discriminant analysis, a seven-variable function was constructed that divided the patients into three groups: (1) those likely to show response to intensive dialysis (48 patients, predictive value of 98 percent), (2) those with an intermediate (38 percent) chance of showing response to intensive dialysis (30 patients), and (3) those unlikely to show response to intensive dialysis (14 patients, predictive value of 100 percent). When the function was applied prospectively to 12 patients (eight with success and four with failure), all were classified correctly. Thus, discriminant analysis of patients with uremic pericarditis allows improved selection of patients with uremic pericarditis likely to have response to daily intensive dialysis and early consideration of alternative forms of treatment in patients unlikely to show response to intensive dialysis. However, the model should be validated in the particular institution where it is to be used before its application.

Reversible nephrotic range proteinuria with renal artery stenosis: a clinical example of renin-associated proteinuria

Nephrotic range proteinuria occurred in a 60-year-old woman with renal artery stenosis and marked hyperreninemia. Treatment by nephrectomy produced resolution of both proteinuria and hypertension. The gradual resolution of the proteinuria postoperatively suggested the proteinuria, at least in part, came from the contralateral kidney. Foot process fusion in the nephrectomy specimen suggested it too was a source of proteinuria. A marked degree of hyperreninemia, as was present in this case, may be necessary before massive proteinuria occurs in renal artery stenosis.

Managing desperate emotional behaviour with hypnosis

When no other psychotherapy or pharmacotherapy could prevent debilitation or institutionalization consequent to longstanding frequent repeated maladaptive behaviour, hypnosis has been observed to be effective in suitable patients. A documentation, three cases of such chronic severe behaviour which have been encountered by the author are described; each had been regarded as hopelessly unmanageable by the primary physician at the time of referral for hypnotherapy. Relevant to their suitability for hypnosis, all three patients were able to understand normal speech with difficulty, were able to concentrate well, and were agreeable to using hypnosis.

Body fluid volumes in the spontaneously hypertensive rat

1. Plasma volume, packed cell volume (PCV), blood pressure, extracellular fluid volume (ECFV) and evans blue disappearance rate were measured in conscious spontaneously hypertensive rats and in weight-matched Wistar normotensive rats. 2. Over the weight range studied (250-350 g), plasma and blood volumes were significantly lower in the spontaneously hypertensive rat. Extracellular fluid volumes were similar in the two groups. PCV and Evans blue disappearance rates were significantly higher in the spontaneously hypertensive rat. 3. Negative correlations were obtained between plasma volume and mean arterial pressure and between the plasma/interstitial fluid volume ratio and mean arterial pressure. 4. The normal extracellular fluid volume and the lack of correlation with mean arterial pressure excludes volume expansion as a pressor mechanism during the established phase of hypertension in the spontaneously hypertensive rat.

Haemodynamics of stable renal transplant recipients

1. Haemodynamics, blood volume, plasma renin concentration and creatinine clearance were evaluated in 24 stable renal transplant recipients. 2. The mean cardiac index of the transplant recipients was not different from that of the normal subjects. 3. The transplant recipients comprised eight hypertensive and 16 normotensive patients. The mean cardiac index was the same in eight hypertensive and 16 normotensive patients. Thus the hypertension of stable renal transplant recipients is sustained by a high total peripheral resistance. 4. The mean blood volume, plasma renin concentration and creatinine clearance were similar in eight hypertensive and 16 normotensive patients. Therefore the hypertension of stable renal transplant recipients is not related to blood volume expansion, elevated peripheral renin or low creatinine clearance. The cause of the elevated total peripheral resistance in hypertension in stable renal transplant recipients remains to be elucidated.

Interrelation of the renin system and erythropoietin in rats

Evidence is presented implicating the renin-angiotensin system in the regulation of plasma erythropoietin concentration. Male and female rats were exposed to hypoxia at 0.43 atm for 8 hr. In male rats, individual erythropoietin values showed a positive correlation with renin, renin substrate, and angiotensin I after 8 hr of hypoxia. In female rats, renin was not elevated during hypoxia. However, after renin was injected subcutaneously, plasma renin values became similar to those in male rats and erythropoietin doubled. Individual erythropoietin values of the combined groups showed a positive correlation with plasma renin. A single oral dose of SQ 14225, an angiotensin I-converting enzyme inhibitor, reduced erythropoietin to undetectable levels in renin-injected female rats. Angiotensin II, in subpressor amounts, prevented the suppression of erythropoietin by SQ 14225. SQ 14225 also reduced renin substrate concentration at ambient pressure and during hypoxic exposure. The correlation coefficient between renin substrate and erythropoietin in rats given SQ 14225 to lower substrate or angiotensin II to increase substrate was 0.85; p < 0.0005. The increase in renin substrate that occurred during hypoxia in female rats given angiotensin II correlated positively with erythropoietin, r = 0.86; p < 0.0005.

Sequential hemodynamic changes in end-stage renal disease and the anephric state during volume expansion

The sequence of hemodynamic events during periods of salt- and water-loading was studied in anephric patients and those with end-stage kidney disease. The 10 patients studied showed four different sequential hemodynamic patterns: 1) no significant increase in blood pressure (BP) in two patients; 2) increase in BP associated with an increase in cardiac output and without change in total peripheral resistance in two patients; 3) increase in BP associated with an increase in total peripheral resistance from the beginning without an increase in cardiac output in five patients; and 4) increase in BP associated with an initial increase in cardiac output followed by an increase in total peripheral resistance in one patient. There was a significant positive correlation between BP and blood volume and between BP and total exchangeable sodium in the patients in whom salt- and water-loading increased the BP. It is concluded that during salt- and water-loading an initial rise in cardiac output is not necessary to increase BP and that a sustained rise in cardiac output does not always increase the total peripheral resistance. Mechanisms other than whole-body autoregulation play a role in increasing BP during salt- and water-loading in patients deprived of renal excretory function.

Clinically occult diffuse proliferative lupus nephritis. An age-related phenomenon

Thirteen patients with systemic lupus erythematosus (SLE) who had normal results of urinalysis, absence of proteinuria, and normal serum creatinine values underwent renal biopsy. Three of 13 patients had diffuse proliferative glomerulonephritis (group 1). Biopsy specimens showed segmental fibrinoid necrosis, diffuse mesangial hypercellularity, and substantial immunoglobulin deposition. Group 2 comprised those patients whose histologic findings did not portend a poor prognosis. Four had mesangial proliferative glomerulonephritis, three had focal proliferative glomerulonephritis, and three had minimal mesangial widening. The values of inulin clearance in group 1 did not differ significantly from those in group 2. Patients in group 1 had a mean age of 19 years, a value significantly lower than in group 2 (41.8 years). Review of previous reports also supports the thesis that this phenomenon is age related. Our study underscores the importance of renal biopsy in patients with SLE despite the absence of clinical evidence of renal involvement, particularly in patients under 30 years of age.

Neurogenic activity--angiotensin II interaction during the development and maintenance of renal hypertension in the rat

1. Pentolinium tartrate (a ganglionic blocker) was injected in conscious rats during the early and late phases of two-kidney renal hypertension produced by aortic ligation. 2. In the early phase ( 5 days after aortic ligation), ganglionic blockade resulted in a decrease in blood pressure equal to that obtained in normotensive rats. Later, at days 12 and 40, for equally severe hypertension, ganglion blockade resulted in a greater decrease in blood pressure. 3. A 30 min infusion of [Sar1, Ala8]angiotensin II during the pentolinium-induced nadir in blood pressure resulted in a further decrease in blood pressure at day 5. Later, at days 12 and 40, this effect was smaller. 4. A 300 min infusion of [Sar1, Ala8]angiotensin II normalized the blood pressure in hypertensive rats at day 40. This delay response may be secondary to a central effect of the antagonist, reducing neurogenic tone or peripheral antagonism of locally generated angiotensin II in the blood vessel walls. 5. At day 40, removal of the small left kidney resulted in a greater decrease in blood pressure. This suggests the presence of a renal factor other than renin in the chronic phase of this hypertension.

Glomerular lesions in benign essential hypertension. A study of eight biopsy specimens with laboratory evidence suggestive of glomerular abnormalities

We performed renal biopsies on eight patients who had benign essential hypertension but laboratory abnormalities suggestive of glomerulonephritis. Persistent microscopic hematuria was detected in four patients, proteinuria in five, RBC casts in two, and decreased glomerular filtration in seven. In all eight biopsy specimens, we detected hyaline arterionephrosclerosis, focal glomerular obsolescence, and segmental, afibrillar thickening of glomerular basement membranes. Direct immunofluorescence studies performed on all eight samples were negative for immunoglobulins, complement, and fibrinogen. Although the patients in our study had laboratory findings suggestive of glomerulonephritis, the morphologic changes were indicative of benign essential hypertension.

Long-term clinical effects, bioavailability, and kinetics of minoxidil in relation to renal function

Minoxidil was used to treat 26 patients (17 to 67 years old) with severe hypertension and varying degrees of renal function. Our object was to assess long-term clinical efficacy, kinetics (acute and chronic), and bioavailability of minoxidil in chronic renal insufficiency. Minoxidil, 27 to 30 mg per day, decreased systolic and diastolic blood pressure during the first three months of therapy. Between the third and 24th months (30 months in one patient) there was no further change. Propranolol or clonidine was needed to control heart rate, and furosemide or dialysis was needed to control edema induced by minoxidil. Renal function improved in some of the mildy azotemic patients. Minoxidil kinetics after the customary dose did not differ whether the drug was taken as tablet or solution. Kinetic parameters during chronic administration of minoxidil did not differ from those after acute administration. The kinetics in chronic renal insufficiency do not differ from these in subjects with normal renal function.