A role for tubular Na+/H+ exchanger NHE3 in the natriuretic effect of the SGLT2 inhibitor empagliflozin

Inhibitors of proximal tubular Na⁺-glucose cotransporter 2 (SGLT2) are natriuretic, and they lower blood pressure. There are reports that the activities of SGLT2 and Na⁺-H⁺ exchanger 3 (NHE3) are coordinated. If so, then part of the natriuretic response to an SGLT2 inhibitor is mediated by suppressing NHE3. To examine this further, we compared the effects of an SGLT2 inhibitor, empagliflozin, on urine composition and systolic blood pressure (SBP) in nondiabetic mice with tubule-specific NHE3 knockdown (NHE3-ko) and wild-type (WT) littermates. A single dose of empagliflozin, titrated to cause minimal glucosuria, increased urinary excretion of Na⁺ and bicarbonate and raised urine pH in WT mice but not in NHE3-ko mice. Chronic empagliflozin treatment tended to lower SBP despite higher renal renin mRNA expression and lowered the ratio of SBP to renin mRNA, indicating volume loss. This effect of empagliflozin depended on tubular NHE3. In diabetic Akita mice, chronic empagliflozin enhanced phosphorylation of NHE3 (S552/S605), changes previously linked to lesser NHE3-mediated reabsorption. Chronic empagliflozin also increased expression of genes involved with renal gluconeogenesis, bicarbonate regeneration, and ammonium formation. While this could reflect compensatory responses to acidification of proximal tubular cells resulting from reduced NHE3 activity, these effects were at least in part independent of tubular NHE3 and potentially indicated metabolic adaptations to urinary glucose loss. Moreover, empagliflozin increased luminal α-ketoglutarate, which may serve to stimulate compensatory distal NaCl reabsorption, while cogenerated and excreted ammonium balances urine losses of this "potential bicarbonate." The data implicate NHE3 as a determinant of the natriuretic effect of empagliflozin.

Western Diet Promotes Renal Injury, Inflammation, and Fibrosis in a Murine Model of Alström Syndrome

INTRODUCTION

Alström syndrome is a rare recessive genetic disease caused by mutations in ALMS1, which encodes a protein that is related to cilia function and intracellular endosome trafficking. The syndrome has been linked to impaired glucose metabolism and CKD. Polymorphisms in Alms1 have likewise been linked to CKD, but little is known about the modification of the phenotype by environmental factors.

METHODS

To gain further insights, the fat aussie (foz) mouse strain, a genetic murine model of Alström syndrome, was exposed to a normal chow (NC) or to a Western diet (WD, 20% fat, 34% sucrose by weight, and 0.2% cholesterol) and renal outcomes were measured.

RESULTS

Body weight and albuminuria were higher in foz than in wild-type (WT) mice on both diets but WD significantly increased the difference. Measurement of plasma creatinine and cystatin C indicated that glomerular filtration rate was preserved in foz versus WT independent of diet. Renal markers of injury, inflammation, and fibrosis were similar in both genotypes on NC but significantly greater in foz than in WT mice on WD. A glucose tolerance test performed in foz and WT mice on WD revealed similar basal blood glucose levels and subsequent blood glucose profiles.

CONCLUSIONS

WD sensitizes a murine model of Alström syndrome to kidney injury, inflammation, and fibrosis, an effect that may not be solely due to effects on glucose metabolism. Polymorphisms in Alms1 may induce CKD in part by modulating the deleterious effects of high dietary fat and sucrose on kidney outcome.

Prediabetes Induced by a Single Autoimmune B Cell Clone

While B cells play a significant role in the onset of type-1 diabetes (T1D), little is know about their role in those early stages. Thus, to gain new insights into the role of B cells in T1D, we converted a physiological early pancreas-infiltrating B cell into a novel BCR mouse model using Somatic Cell Nuclear Transfer (SCNT). Strikingly, SCNT-derived B1411 model displayed neither developmental block nor anergy. Instead, B1411 underwent spontaneous germinal center reactions. Without T cell help, B1411-Rag1^−/− was capable of forming peri-/intra-pancreatic lymph nodes, and undergoing class-switching. RNA-Seq analysis identified 93 differentially expressed genes in B1411 compared to WT B cells, including Irf7, Usp18, and Mda5 that had been linked to a potential viral etiology of T1D. We also found various members of the oligoadenylate synthase (OAS) family to be enriched in B1411, such as Oas1, which had recently also been linked to T1D. Strikingly, when challenged with glucose B1411-Rag1^−/− mice displayed impaired glucose tolerance.

Gene knockout of the Na+-glucose cotransporter SGLT2 in a murine model of acute kidney injury induced by ischemia-reperfusion

In the early proximal tubule, Na⁺-glucose cotransporter 2 (SGLT2) mediates the bulk of renal glucose reabsorption. Gene deletion in mice (Sglt2^-/-) was used to determine the role of SGLT2 in acute kidney injury induced by bilateral ischemia-reperfusion (IR). In Sglt2^-/- and littermate wild-type mice, plasma creatinine increased similarly on day 1 after IR. This was associated with an equal increase in both genotypes in the urinary kidney injury molecule-1-to-creatinine ratio, a tubular injury marker, and similarly reduced urine osmolality and increased plasma osmolality, indicating impaired urine concentration. In both IR groups, FITC-sinistrin glomerular filtration rate was equally reduced on day 14, and plasma creatinine was similarly and incompletely restored on day 23. In Sglt2^-/- mice subjected to IR, fractional urinary glucose excretion was increased on day 1 but reduced and associated with normal renal Na⁺-glucose cotransporter 1 (Sglt1) mRNA expression on day 23, suggesting temporary SGLT1 suppression. In wild-type mice subjected to IR, renal Sglt1 mRNA was likewise normal on day 23, whereas Sglt2 mRNA was reduced by 57%. In both genotypes, IR equally reduced urine osmolality and renal mRNA expression of the Na⁺-K⁺-2Cl^- cotransporter and renin on day 23, suggesting thick ascending limb dysfunction, and similarly increased renal mRNA expression of markers of injury, inflammation, oxidative stress, and fibrosis (kidney injury molecule-1, neutrophil gelatinase-associated lipocalin, monocyte chemoattractant protein-1, transforming growth factor-β1, NADPH oxidase-2, and collagen type 1). This was associated with equal increases in kidney histological damage scores and similar degree of capillary loss in both genotypes. The data indicate that genetic deletion of SGLT2 did not protect the kidneys in the initial injury phase or the subsequent recovery phase in a mouse model of IR-induced acute kidney injury.

Effect of renal tubule-specific knockdown of the Na+/H+ exchanger NHE3 in Akita diabetic mice

Na+/H+ exchanger isoform 3 (NHE3) contributes to Na+/bicarbonate reabsorption and ammonium secretion in early proximal tubules. To determine its role in the diabetic kidney, type 1 diabetic Akita mice with tubular NHE3 knockdown [Pax8-Cre; NHE3-knockout (KO) mice] were generated. NHE3-KO mice had higher urine pH, more bicarbonaturia, and compensating increases in renal mRNA expression for genes associated with generation of ammonium, bicarbonate, and glucose (phosphoenolpyruvate carboxykinase) in proximal tubules and H+ and ammonia secretion and glycolysis in distal tubules. This left blood pH and bicarbonate unaffected in nondiabetic and diabetic NHE3-KO versus wild-type mice but was associated with renal upregulation of proinflammatory markers. Higher renal phosphoenolpyruvate carboxykinase expression in NHE3-KO mice was associated with lower Na+-glucose cotransporter (SGLT)2 and higher SGLT1 expression, indicating a downward tubular shift in Na+ and glucose reabsorption. NHE3-KO was associated with lesser kidney weight and glomerular filtration rate (GFR) independent of diabetes and prevented diabetes-associated albuminuria. NHE3-KO, however, did not attenuate hyperglycemia or prevent diabetes from increasing kidney weight and GFR. Higher renal gluconeogenesis may explain similar hyperglycemia despite lower SGLT2 expression and higher glucosuria in diabetic NHE3-KO versus wild-type mice; stronger SGLT1 engagement could have affected kidney weight and GFR responses. Chronic kidney disease in humans is associated with reduced urinary excretion of metabolites of branched-chain amino acids and the tricarboxylic acid cycle, a pattern mimicked in diabetic wild-type mice. This pattern was reversed in nondiabetic NHE3-KO mice, possibly reflecting branched-chain amino acids use for ammoniagenesis and tricarboxylic acid cycle upregulation to support formation of ammonia, bicarbonate, and glucose in proximal tubule. NHE3-KO, however, did not prevent the diabetes-induced urinary downregulation in these metabolites.

Gene deletion of the Na+-glucose cotransporter SGLT1 ameliorates kidney recovery in a murine model of acute kidney injury induced by ischemia-reperfusion

Renal Na+-glucose cotransporter SGLT1 mediates glucose reabsorption in the late proximal tubule, a hypoxia-sensitive tubular segment that enters the outer medulla. Gene deletion in mice (Sglt1-/-) was used to determine the role of the cotransporter in acute kidney injury induced by ischemia-reperfusion (IR), including the initial injury and subsequent recovery phase. On days 1 and 16 after IR, absolute and fractional urinary glucose excretion remained greater in Sglt1-/- mice versus wild-type (WT) littermates, consistent with a sustained contribution of SGLT1 to tubular glucose reabsorption in WT mice. Absence of SGLT1 did not affect the initial kidney impairment versus WT mice, as indicated by similar increases on day 1 in plasma concentrations of creatinine and urinary excretion of the tubular injury marker kidney injury molecule-1 as well as a similar rise in plasma osmolality and fall in urine osmolality as indicators of impaired urine concentration. Recovery of kidney function on days 14/16, however, was improved in Sglt1-/- versus WT mice, as indicated by lower plasma creatinine, higher glomerula filtration rate (by FITC-sinistrin in awake mice), and more completely restored urine and plasma osmolality. This was associated with a reduced tubular injury score in the cortex and outer medulla, better preserved renal mRNA expression of tubular transporters (Sglt2 and Na+-K+-2Cl- cotransporter Nkcc2), and a lesser rise in renal mRNA expression of markers of injury, inflammation, and fibrosis [kidney injury molecule-1, chemokine (C-C motif) ligand 2, fibronectin 1, and collagen type I-α1] in Sglt1-/- versus WT mice. These results suggest that SGLT1 activity in the late proximal tubule may have deleterious effects during recovery of IR-induced acute kidney injury and identify SGLT1 as a potential therapeutic target.

Knockout of Na+-glucose cotransporter SGLT1 mitigates diabetes-induced upregulation of nitric oxide synthase NOS1 in the macula densa and glomerular hyperfiltration

Na⁺-glucose cotransporter (SGLT)1 mediates glucose reabsorption in late proximal tubules. SGLT1 also mediates macula densa (MD) sensing of an increase in luminal glucose, which increases nitric oxide (NO) synthase 1 (MD-NOS1)-mediated NO formation and potentially glomerular filtratrion rate (GFR). Here, the contribution of SGLT1 was tested by gene knockout (-/-) in type 1 diabetic Akita mice. A low-glucose diet was used to prevent intestinal malabsorption in Sglt1^-/- mice and minimize the contribution of intestinal SGLT1. Hyperglycemia was modestly reduced in Sglt1^-/- versus littermate wild-type Akita mice (480 vs. 550 mg/dl), associated with reduced diabetes-induced increases in GFR, kidney weight, glomerular size, and albuminuria. Blunted hyperfiltration was confirmed in streptozotocin-induced diabetic Sglt1^-/- mice, associated with similar hyperglycemia versus wild-type mice (350 vs. 385 mg/dl). Absence of SGLT1 attenuated upregulation of MD-NOS1 protein expression in diabetic Akita mice and in response to SGLT2 inhibition in nondiabetic mice. During SGLT2 inhibition in Akita mice, Sglt1^-/- mice had likewise reduced blood glucose (200 vs. 300 mg/dl), associated with lesser MD-NOS1 expression, GFR, kidney weight, glomerular size, and albuminuria. Absence of Sglt1 in Akita mice increased systolic blood pressure, associated with suppressed renal renin mRNA expression. This may reflect fluid retention due to blunted hyperfiltration. SGLT2 inhibition prevented the blood pressure increase in Sglt1^-/- Akita mice, possibly due to additive glucosuric/diuretic effects. The data indicate that SGLT1 contributes to diabetic hyperfiltration and limits diabetic hypertension. Potential mechanisms include its role in glucose-driven upregulation of MD-NOS1 expression. This pathway may increase GFR to maintain volume balance when enhanced MD glucose delivery indicates upstream saturation of SGLTs and thus hyperreabsorption.

SGLT2 inhibition and renal urate excretion: role of luminal glucose, GLUT9, and URAT1

Inhibitors of the Na⁺-glucose cotransporter SGLT2 enhance urinary glucose and urate excretion and lower plasma urate levels. The mechanisms remain unclear, but a role for enhanced glucose in the tubular fluid, which may interact with tubular urate transporters, such as the glucose transporter GLUT9 or the urate transporter URAT1, has been proposed. Studies were performed in nondiabetic mice treated with the SGLT2 inhibitor canagliflozin and in gene-targeted mice lacking the urate transporter Glut9 in the tubule or in mice with whole body knockout of Sglt2, Sglt1, or Urat1. Renal urate handling was assessed by analysis of urate in spontaneous plasma and urine samples and normalization to creatinine concentrations or by renal clearance studies with assessment of glomerular filtration rate by FITC-sinistrin. The experiments confirmed the contribution of URAT1 and GLUT9 to renal urate reabsorption, showing a greater contribution of the latter and additive effects. Genetic and pharmacological inhibition of SGLT2 enhanced fractional renal urate excretion (FE-urate), indicating that a direct effect of the SGLT2 inhibitor on urate transporters is not absolutely necessary. Consistent with a proposed role of increased luminal glucose delivery, the absence of Sglt1, which by itself had no effect on FE-urate, enhanced the glycosuric and uricosuric effects of the SGLT2 inhibitor. The SGLT2 inhibitor enhanced renal mRNA expression of Glut9 in wild-type mice, but tubular GLUT9 seemed dispensable for the increase in FE-urate in response to canagliflozin. First evidence is presented that URAT1 is required for the acute uricosuric effect of the SGLT2 inhibitor in mice.

Organic anion transporter OAT3 enhances the glucosuric effect of the SGLT2 inhibitor empagliflozin

The sodium-glucose cotransporter SGLT2 inhibitor empagliflozin (plasma protein binding ~88%) may reach its target in the brush border of the early proximal tubule by glomerular filtration and tubular secretion. Here we determined whether empagliflozin is secreted by renal tubules in mice and whether genetic knockout of the basolateral organic anion transporter 3 ( Oat3-/-) affects its tubular secretion or glucosuric effect. Renal clearance studies in wild-type (WT) mice showed that tubular secretion accounted for 50-70% of empagliflozin urinary excretion. Immunostaining indicated that SGLT2 and OAT3 localization partially overlapped in proximal tubule S1 and S2 segments. Glucosuria in metabolic cage studies was reduced in Oat3-/- vs. WT mice for acute empagliflozin doses of 1, 3, and 10 mg/kg, whereas 30 mg/kg induced similar maximal glucosuria in both genotypes. Chronic application of empagliflozin (~25 mg·kg^-1 ·day^-1) in Oat3-/- mice was associated with lower urinary glucose-to-creatinine ratios despite maintaining slightly higher blood glucose levels than WT. On a whole kidney level, renal secretion of empagliflozin was largely unchanged in Oat3-/- mice. However, the absence of OAT3 attenuated the influence of empagliflozin on fractional glucose excretion; higher levels of plasma or filtered empagliflozin were needed to induce similar increases in fractional renal glucose excretion. We conclude that empagliflozin is excreted into the urine to similar extent by glomerular filtration and tubular secretion. The latter can occur largely independent of OAT3. However, OAT3 increases the glucosuric effect of empagliflozin, which may relate to the partial overlap of its localization with SGLT2 and thus OAT3-mediated tubular secretion of empagliflozin in the early proximal tubule.

l-citrulline prevents asymmetric dimethylarginine-mediated reductions in nitric oxide and nitrosative stress in primary human airway epithelial cells

BACKGROUND

Asthma is associated with reduced systemic levels of l-arginine and increased asymmetric dimethylarginine (ADMA). This imbalance leads to nitric oxide synthase (NOS) uncoupling with reduced nitric oxide (NO) formation and greater oxidative and nitrosative stress. Whether this imbalance also occurs in bronchial epitheliumof asthmatics is unknown.

OBJECTIVES

We used primary human bronchial epithelial cells (HBECs) from asthmatics and healthy controls to evaluate: (i) ADMA-mediated NOS uncoupling reduces epithelial production of NO and increases oxygen and nitrogen reactive species, and (ii) l-citrulline can reverse this mechanism by recoupling NOS, restoring NO production and reducing oxidative and nitrosative stress.

RESULTS

In HBECsIL-13 and INFγ stimulated NOS2 and increased NOx levels. The addition of ADMA reduced NOx and increased H₂ O₂ levels (p<0.001). Treatment with l-citrulline (800, 1600 μm) rescued NOx when the l-arginine media concentration was 25 μm but failed to do so with higher concentrations (100 μm). Under reduced l-arginine media conditions, HBECs treated with l-citrulline increased the levels of argininosuccinate, an enzyme that metabolizes l-citrulline to l-arginine. l-citrulline prevented the ADMA-mediated increase in nitrotyrosine in HBECs in cells from asthmatics and controls.

CONCLUSIONS AND CLINICAL RELEVANCE

Increasing ADMA reduces NO formation and increases oxidative and nitrosative stress in airway epithelial cells. l-citrulline supplementation restores NO formation, while preventing nitrosative stress. These results, suggest that l-citrulline supplementation may indeed be a powerful approach to restore airway NO production and may have a therapeutic potential in diseases in which there is a defective production of NO.

Television advertising, not viewing, is associated with negative dietary patterns in children

BACKGROUND

Children's exposure to unhealthy food marketing is a contributor to poor diets and weight gain. Television food advertising, in particular, has been the focus of research and policy discussions.

OBJECTIVES

We aimed to quantify the specific impact of television advertising, as distinct from television viewing generally, on children's usual diet. Methods Four hundred seventeen Australian children aged 10-16 participated in an online survey, which assessed television viewing habits and consumption of 12 frequently advertised unhealthy foods/drinks. Consumption of these foods/drinks was dichotomized (less weekly, weekly or more) and summed (1 point for each item consumed weekly or more) to give cumulative consumption scores.

RESULTS

After adjusting for age and socioeconomic status, there was strong evidence of an increase in unhealthy food score (P < 0.001), drink score (P = 0.002) and food/drink combined score (P < 0.001), with increasing commercial television viewing.

CONCLUSIONS

The link between television viewing and poor diet was strongest for children who watched the most commercial television, and those who were actually exposed to advertisements embedded within programs. This association between advertisement exposure and poor diet emphasizes the need for public policy intervention to reduce children's food advertising exposures.

Fault seal calibration: a brief review

Calibration is a necessary step in the workflow for prediction of fault seal because there is no direct way to detect the hydraulic behaviour of a fault at the scale of a hydrocarbon trap. Over the last 20 years two general approaches have been developed:

A Phase 1 Study To Assess the Safety, Tolerability and Pharmacokinetics of ARRY-380 – An Oral Inhibitor of HER2

Background: ARRY-380 is a potent, orally active small molecule that selectively inhibits HER2 signaling in vitro and in vivo and significantly inhibits tumor growth in a variety of HER2-dependent tumor xenograft models. Based on its preclinical activity, tolerability and pharmacokinetic (PK) profile, a Phase 1 study was initiated to evaluate the safety, tolerability and PK profile of ARRY-380 as a single agent in patients with solid tumors and to establish the maximum tolerated dose (MTD).Methods: Patients with HER2 positive breast cancer or other tumor types for which published evidence of HER2 expression exists were treated with ARRY-380 as a single oral dose on Cycle 1 Day 1, followed by continuous twice-daily (BID) oral dosing starting on Cycle 1 Day 3. ARRY-380 was escalated in cohorts of 3 to 4 patients, using standard dose-limiting toxicity (DLT) criteria during Cycle 1 to determine dose escalation. Serial PK assessments were made during Cycle 1 on Days 1, 2, 3 and at steady-state on Day 15.Preliminary Results: As of June 1, 2009, 15 patients have been treated in 5 dosing cohorts at doses of 25 to 300 mg BID. Patients had a median age of 61 years (range, 37-77 years) and ECOG PS of 0 to 2. Cancer types included HER2+ breast cancer (8), colorectal (6) and salivary gland (1). No DLTs have been observed and drug-related adverse events have included Grade 1 nausea, rash and fatigue and Grade 2 fatigue in 2 patients at the 200 mg BID dose level. Preliminary PK analyses indicate a trend for increasing Cmax and AUC with increasing dose, a median Tmax of 2 hours and a mean t1/2 of 4.6 hours across all cohorts. Two patients with HER2+ breast cancer have had stable disease for ≥ 4 months with no significant toxicity. One of these two patients had a notable reduction in liver metastases (28%) after 2 cycles of ARRY-380 and is currently on study.Conclusions: ARRY-380 has demonstrated an acceptable safety and PK profile and preliminary signs of clinical benefit. Dose escalation continues to determine the MTD.

Citation Information: Cancer Res 2009;69(24 Suppl):Abstract nr 5111.

Markers of the denormalisation of smoking and the tobacco industry

BACKGROUND

In nations with histories of declining smoking prevalence and comprehensive tobacco control policies, smoking-positive cultures have been severely eroded. Smoking, smokers and the tobacco industry are today routinely depicted in everyday discourse and media representations in a variety of overwhelmingly negative ways. Several authors have invoked Erving Goffman's notions of stigmatization to describe the process and impact of this radical transformation, which importantly includes motivating smoking cessation. Efforts to describe nations' progress toward comprehensive tobacco control have hitherto taken little account of the role of cultural change to the meaning of smoking and the many ways in which it has become denormalised.

METHODS

This paper identifies a diversity of generally undocumented yet pervasive markers of the "spoiled identity" of smoking, smokers and the tobacco industry, illustrated with examples from Australia, a nation with advanced tobacco control.

RESULTS

We caution about some important negative consequences arising from the stigmatization of smokers.

CONCLUSIONS

We recommend that schemes rating the comprehensiveness of national tobacco control should be supplemented by documentation of markers of this denormalisation.

Avulsion of ascending lumbar and iliolumbar veins in anterior spinal surgery: An anatomical study

To expose the disc between the 4th and 5th lumbar vertebrae in anterior spinal surgery, left to right retraction of inferior vena cava and aorta is required. This manoeuvre can be complicated by venous haemorrhage that, in most cases, is due to avulsion of the left ascending lumbar vein (ALV) or the left iliolumbar vein (ILV). We dissected 23 embalmed cadavers to assess the factors that contribute to the risk of tearing these two veins during retraction. We describe a triangular region that should help surgeons in identifying the ALV and ILV. This triangle is defined by the lateral border of the common iliac vein, the medial border of the psoas major muscle, and the superior end-plate of the L5 vertebral body. We observed that 3 cm between the termination of the left ALV, or a common stem with the ILV, and the termination of the common iliac vein is the critical distance, less than which the risk of venous avulsion is highest. Although the sample considered is small, our study seems to suggest that male patients tend to have a higher risk of venous avulsion than female patients.

Pharmacokinetic and pharmacodynamic analysis of topotecan administered in combination with PS 341 in patients with advanced malignancy

2033

Background: In vitro exposure to camptothecin results in down-regulation of the target enzyme, topoisomerase I (topo) via multi-ubiquitination and proteasomal degradation of the protein-linked DNA breaks. To prevent loss of topo, and thus circumvent a possible mechanism of resistance to the topo inhibitors, we conducted a dose escalating phase I study of topotecan in combination with the proteosome inhibitor PS 341. We now report the pharmacokinetic and pharmacodynamic analysis of the trial. Methods: Patients with advanced cancer were treated with topotecan alone at the following dose escalating levels: 0.75, 1.0,1,25 and 1.5 mg/m2 as a 60 min infusion d x 5 during cycle 1. In subsequent cycles (21 days), cohorts of 3–6 patients received PS 341 as a 30 min infusion on days 1, 4, 8 and 11 at the following dose levels: 0.6, 0.8, 1.0 and 1.3 mg/m2. Topo expression was determined by western blot on peripheral blood mononuclear cells (PBMCs) sampled throughout the first 5-day treatment period of cycles #1 and 2. Total topotecan plasma pharmacokinetics were studied with the first doses of topotecan on cycle #1 (topotecan alone) and cycle #2 (topotecan after PS 341). Results: Samples were collected from 22 patients and 38 patient-cycles. In the first week of cycle #1, 9 of 22 (41 %) patients demonstrated a significant decrease in topo expression (range 0.2 - 1 fold) compared with the baseline level. Topo levels did not change (7/22, 32%) or increased (6/22, 27%) in the remaining patients. After administration of PS 341 during cycle #2, PBMC from 10 of 17 patients (59 %) analyzed showed a greater than 0.3 fold increase (range: 0.32 to 63) in topo concentration, and topo levels in 4 patients (23 %) were unchanged. Preliminary pharmacokinetic analysis indicates that PS 341 may interact with topotecan. Conclusions: There is a heterogeneous response in PBMC topo levels following administration of topotecan. However, addition of PS 341 to topotecan stabilized or increased PBMC topo I levels in the majority of patients, suggesting a possible role for PS341 in inhibiting camptothecin-induced topo protein degradation. Further studies combining proteasome inhibitors with topotecan to overcome drug resistance based on topo degradation are warranted.

No significant financial relationships to disclose.

Combined family trio and case-control analysis of the COMT Val158Met polymorphism in European patients with anorexia nervosa

The high activity Val158 (H) allele of the dopamine-metabolizing enzyme catechol-O-methyltransferase (COMT) was associated with anorexia nervosa (AN) in a recent family trio-based study of patients from Israel. In an attempt to replicate this finding, we performed a combined family trio and case-control study in an European population from seven centers in six different countries (Austria, Germany, Great Britain, Italy [Milan], Italy [Florence], Slovenia, and Spain), together contributing a total of 372 family trios, 684 controls and 266 cases. TDT analyses of high (H) and low (L) alleles in family trios showed that H allele and L allele were each transmitted 101 times (chi(2) = 0, ns). Allele-wise case-control analysis using separate samples simply combined from the centers was also not significant, with the frequencies of the H allele 50% in cases and same in controls. Stratified analysis of data from all centers gave an odds ratio of 0.98 (Cornfield 95% confidence limits 0.78-1.24). Analysis by genotype was likewise not significant (overall chi(2) = 0.42). Because we were not able to support the primary hypothesis that Val158Met is a risk factor for AN, we did not perform secondary analysis of minimum body mass index (mBMI), age at onset or illness subtype (restricting or binge purging anorexia). Overall we found no support for the hypothesis that the Val158 allele of COMT gene is associated with AN in our combined European sample.

Measurement of the linear dynamics of the descent of the bovine fetal testis

Measurements were made on 86 male bovine fetuses collected from abattoirs in the vicinity of Sydney, Australia. The fetal body length was used to calculate the approximate day of gestational age (DGA); most fetuses were between 60 and 150 DGA. The distances from the caudal pole of the kidney (metanephros) to, respectively, the tip of the scrotum, the distal end of the testis and the internal ring of the inguinal canal were measured, as well as the dimensions of the testis and gubernaculum testis. Distances of (1) testis to inguinal canal, (2) inguinal canal to scrotum, (3) testis to scrotum and (4) gubernaculum to scrotum were calculated from these measurements, which were made on both left and right sides. The total length of the gubernaculum testis increased during transabdominal passage and during transinguinal passage of the testis. Furthermore, the gubernaculum appeared to maintain the testis at a relatively fixed distance from the scrotum during transabdominal passage so that the inguinal canal appeared to move towards the testis. The greatest distance between the testis and the tip of the scrotum was found during the transinguinal passage of the testis and was 2.8 cm for the left testis and 2.3 cm for the right. When located within the scrotum, each testis was still 1.6-1.7 cm from the tip of the scrotum, so the distance to be traversed was only 0.6-1.2 cm. Following passage of the testis through the inguinal canal, the gubernaculum became shorter and its distal tip was displaced toward the distal end of the scrotum. Traction by the gubernaculum could account for the final transposition of the testis from the external inguinal ring to the scrotum. Other factors involved in displacement of the testis include differential growth patterns as well as increases in the dimensions of the testis itself.

DNA from buccal swabs recruited by mail: evaluation of storage effects on long-term stability and suitability for multiplex polymerase chain reaction genotyping

We provide details of an inexpensive and rapid method for extraction of DNA from buccal swabs (including samples received through the mail) and from a range of other tissue samples. The procedure we have developed provides amounts of DNA adequate for several thousand polymerase chain reactions (PCRs), and we have validated its potential for long-term storage. Samples stored for > 4 years are of comparable concentration and provide as robust PCR templates as those tested immediately after extraction. The availability of this technology is of considerable significance in planning DNA banks from population collections and cohorts.

Low exhaled nitric oxide and a polymorphism in the NOS I gene is associated with acute chest syndrome

Abnormalities of nitric oxide metabolism have been implicated in the pathogenesis of acute chest syndrome in subjects with sickle cell anemia. It is not known whether exhaled nitric oxide levels (FE(NO)) are abnormal in children with a history of the acute chest syndrome (ACS). We compared FE(NO), plasma nitric oxide metabolites (NO(x)), serum arginine and citrulline levels, and the number of AAT repeats in intron 20 of NOS I in subjects with sickle cell disease (SCD) and a history of at least one episode of ACS (ACS(+), n = 13), subjects with SCD and no prior history of ACS (ACS(-), n = 7), and healthy children (HC, n = 6). Mean +/- SD FE(NO) (ppb) was lower in ACS(+) than in ACS(-) and HC: (10.4 +/- 4.3 versus 23.4 +/- 6.1 p = 0.002] and 30.4 +/- 15.8 [p = 0.0001], respectively). Plasma NO(x) (microM) were similar in all three groups (37.3 +/- 19.4, 33.0 +/- 13.2, 44.7 +/- 7.8, respectively). Arginine and citrulline levels (microM) did not differ between ACS(+) and ACS(-) groups. Spirometric data revealed a mildly diminished FEV(1) and FVC in ACS(+) that was statistically different from HC but not ACS(-): (FEV(1) as % of predicted for ACS(+), ACS(-), and HC; 83 +/- 17 versus 87 +/- 16 versus 102 +/- 16, respectively, p < 0.05 between ACS(+) and HC). The level of FE(NO) was significantly associated with the sum of AAT repeats in intron 20 of NOS I gene alleles. The correlation coefficient (r) was 0.62 (p < 0.005). We conclude that FE(NO) levels are significantly reduced in subjects who have a history of ACS and that the FE(NO) levels are significantly correlated with the number of NOS I AAT repeats. FE(NO) is a sensitive marker and may be a predictor of ACS prone children.

Improved compliance with universal precautions in the operating room following an educational intervention

Observation of surgical personnel in four specialties (cardiothoracic, general, gynecologic, and orthopedic) in the operating room was performed prior to implementation of an educational intervention designed to improve compliance with Universal Precautions and at 1- and 2-years post-intervention. Use of protective eyewear and double gloving increased following the intervention, whereas the incidence of documented blood and body fluid exposures decreased.

Cytologic findings in a fetal intracranial teratoma. A case report

BACKGROUND

Fetal neoplasms are very rare. Recently we had the opportunity to examine the fine needle aspiration (FNA) biopsy of a fetal intracranial teratoma.

CASE

The tumor was found in a 30-week-gestation fetus; the mother was 32 years old, gravida 4, para 1. She presented with a rapid increase in abdominal girth over a two-week period. An ultrasound scan showed severe fetal hydrocephalus and a massive intracranial tumor thought to be a teratoma because of variations in echogenicity and spotty calcification. An FNA biopsy was performed under ultrasound guidance. It showed mainly neuroepithelial cells, so a differential diagnosis of malignant neuroepithelial tumor was considered. At autopsy, several other tissue types were found in the tumor, consistent with a teratoma.

CONCLUSION

Advances in diagnosis of fetal anomalies by ultrasound have been associated with an increase in the use of fetal interventions performed in utero. This includes the availability of fetal surgery in some centers. FNA biopsy of fetal lesions does not appear to be well described. Increased experience with this technique is necessary if its full potential is to be realized.

Na,K-ATPase gene transfer mitigates an oxidant-induced decrease of active sodium transport in rat fetal ATII cells

We investigated whether adenovirus-mediated transfer of genes encoding for subunits of the Na,K-ATPase increases transepithelial Na(+) transport in rat fetal distal lung epithelial (FDLE) monolayers and renders them more resistant to hydrogen peroxide injury. FDLE cells, isolated from rat fetuses at a gestational age of 19 to 20 d (22 d = term), were seeded on filters and infected with replication-incompetent human type 5 adenoviruses containing complementary DNAs encoding for rat Na,K-ATPase alpha(1) or beta(1) subunits (ad alpha(1) and ad beta(1), respectively). Once confluent monolayers were formed, the filters were mounted in Ussing chambers and short circuit currents (I(SC)) were measured. Increased levels of alpha(1) or beta(1) subunit proteins after infection with ad alpha(1) and ad beta(1), respectively, were confirmed by Western blot analysis. Baseline I(SC) increased after transfection with 2 plaque-forming units (pfu) of ad beta(1) from 5.1 +/- 0.3 to 6.1 +/- 0.3 microA/cm(2) (mean +/- SEM; P < 0.05). Permeabilization of the apical membrane with amphotericin B caused a large increase in I(SC); the ouabain-sensitive component of the amphotericin B-elicited I(SC) (ouab(max)) was increased from 4.0 +/- 0.2 (n = 69) in controls to 4.8 +/- 0.2 (n = 15), 5.9 +/- 0.3 (n = 53), 6.9 +/- 0.4 (n = 25), 7.7 +/- 0.9 (n = 16) in monolayers infected with 1, 2, 11, and 22 pfu of ad beta(1), respectively; transfection with ad alpha(1) had no effect on any measured variables. Further, transfection with ad beta(1) in comparison to noninfected monolayers resulted in higher baseline and ouab(max) I(SC) after injury with 500 microM H(2)O(2). We conclude that overexpression of the beta(1) subunit of the Na,K-ATPase may help maintain normal levels of vectorial Na(+) transport across ATII cell monolayers in pathologic conditions.