Efficacy and safety of intravenously administered dofetilide in acute termination of atrial fibrillation and flutter: a multicenter, randomized, double-blind, placebo-controlled trial. Danish Dofetilide in Atrial Fibrillation and Flutter Study Group

BACKGROUND

This study was designed to assess the efficacy and safety of intravenous dofetilide in acute termination of atrial fibrillation (AF) and flutter (AFL). Dofetilide, an investigational class III antiarrhythmic agent, selectively inhibits the rapid component of the delayed rectifier potassium current, thus prolonging the effective refractory period and duration of the action potential. Dofetilide can be administered intravenously and has a rapid onset of electrophysiologic action.

METHODS AND RESULTS

Ninety-six patients with AF (n = 79) or AFL (n = 17) with a median arrhythmia duration of 62 days (range 1 to 180) were randomized to placebo (n = 30) or 8 micrograms/kg IV dofetilide (n = 66) over 30 minutes. Conversion was defined as termination of the atrial arrhythmia within 3 hours from the start of infusion. The conversion rate was 30.3% after dofetilide and 3.3% after placebo (P <.006). Conversion rate was higher in AFL than in AF: 64% versus 24% (P =. 012). In nonconverters, there was no statistically significant difference between the change in heart rate among the dofetilide-treated compared with the placebo-treated patients (P =. 42). Torsade de pointes ventricular tachycardia developed in 2 patients (3%). In both patients, drug infusion was discontinued before the event because of prolongation of the QT interval.

CONCLUSIONS

Intravenous dofetilide is effective in acute termination of AF and AFL of medium duration, with a particularly high efficacy rate in AFL. A small but serious risk of proarrhythmia must be anticipated.

The optimal oesophageal pacing technique--the importance of body position, interelectrode spacing, electrode surface area, pacing waveform and intra-oesophageal local anaesthesia

In order to improve the technique of transoesophageal atrial stimulation (TAS), the effects of body position, interelectrode spacing and electrode surface area on pacing threshold were assessed in two substudies. The effects of intra-oesophageal local anaesthesia and of two different pacing wave configurations on pacing threshold and discomfort were also assessed. Substudy I comprised 16 subjects (3 patients with a history of paroxysmal supraventricular tachycardia and 13 healthy volunteers) and substudy II comprised 16 healthy volunteers. TAS was performed using a hexapolar luminal prototype oesophageal electrode catheter. In substudy I bipolar pacing was performed in the semi-supine and left decubitus body positions for different pulse durations (20, 10, 6 and 2 ms), interelectrode pole distances (10 to 24 mm) and electrode pole surface areas (0.22 to 0.66 cm2). In substudy II TAS was performed with square wave and triangular waveform pulses after intra-oesophageal saline and lidocaine 20 mg/ml. These solutions were given in random order. Neither the interelectrode distance nor electrode surface areas had any significant influence on pacing thresholds. Stimulation thresholds were not affected by body position. Intraoesophageal lidocaine did not affect the discomfort experienced. Peak pacing thresholds using a triangular waveform were significantly higher than thresholds using a square waveformn (p < 0.001). The optimal pacing technique for TAS remains to be defined. The TAS-induced pain is probably not generated from the oesophageal mucous membrane. There is a significant difference in pacing thresholds between triangular and square waveforms.

Variability in the mechanical properties of spider silks on three levels: interspecific, intraspecific and intraindividual

The mechanical characteristics of dragline silks collected from a range of spiders drawn from the Argiopidae, Tetragnathidae, Theridiidae and Pisauridae displayed significant inter- and intraspecific differences. Dragline silks of the same species could show considerable variability probably dependent upon spider condition: starvation, for example, lead to decreased breaking elongation in Nephila edulis. Environmental conditions such as reeling speed affected silk properties such that (i) breaking elongation decreased, (ii) breaking stress increased and (iii) Young's modulus increased with increasing reeling speed. However, N. edulis and Araneus diadematus responded differently to the reeling speed treatments suggesting differences in basic silk properties.

[Adults treated as children for acute lymphocytic leukemia--methotrexate, late effects and quality of life]

From 1975 to 1980, 153 Norwegian children were diagnosed with acute lymphocytic leukaemia. In 1995, all 98 survivors were studied and compared to matched family controls. 132 children were treated with the national protocol. Of these, 93 (70.5%) were survivors at the time of the study. The remaining five survivors were treated with different treatment schemes. The national protocol included methotrexate infusions combined with intrathecal methotrexate as prophylactics against neuroleukaemia, instead of the irradiation. Neither doxorubicin nor cyclophosphamide were included. In this study, a questionnaire was used that covered demographic data, quality of life, and medical information the response rates were 96% (94 persons) for survivors and 92% (90 persons) for family controls. Information was also obtained for the remaining four survivors. No significant differences were found between survivors and controls with regard to quality of life and demographics, with one exception, Somatisation on the GHQ-28. Hospital records of all patients were checked for possible late effects. One case of serious sequela (hemiparesis during therapy) was found, probably related to methotrexate therapy. Seven other serious, possible sequelae were recorded, but probably not related to methotrexate. There were no cases of secondary malignant neoplasm.

Retinoic acid down-regulates the expression of the vasoactive intestinal polypeptide receptor type-1 in human breast carcinoma cell lines

Four breast carcinoma cell lines (T47D, ZR-75-1, MDA-MB-231, and MCF-7) were tested for regulation of the expression of vasoactive intestinal polypeptide receptor type-1 (VIP-R1). In all four cell lines, retinoic acid (RA) treatment caused a fast and marked decrease in VIP-R1 mRNA level as examined by Northern blots. Cycloheximide pretreatment attenuated the effect from 3- to 2-fold, indicating that existing proteins can mediate the decreasing effect of RA, but to attain the maximal effect new protein synthesis might be needed. Transcriptional inhibition with Actinomyocin D showed that RA did not influence the VIP-R1 mRNA half-life, indicating that the decreasing effect of RA on the mRNA level is due to transcriptional inhibition. In agreement with the observations on mRNA level, we found that the VIP receptor number was reduced 3-fold from 88 to 32 fmol/10(6) cells in T47D cells and from 222 to 73 fmol/10(6) cells in MDA-MB-231 cells upon RA treatment for 72 h. The promoter and 5'-flanking region of the VIP-R1 gene were cloned from a human placental cosmid library, and 2.5 kb were sequenced to search for regulatory elements. Our results, therefore, imply that the regulation of VIP-R1 gene expression by RA could have a role in human mammary tumor biology.

Characterization of the inhibitory effect of growth hormone on primary preadipocyte differentiation

GH exerts adipogenic activity in several preadipocyte cell lines, whereas in primary rat preadipocytes, GH has an antiadipogenic activity. To better understand the molecular mechanism involved in adipocyte differentiation, the expression of adipocyte-specific genes was analyzed in differentiating preadipocytes in response to GH. We found that the expression of both adipocyte determination and differentiation factor 1 (ADD1) and peroxisome proliferator activated receptor gamma(PPARgamma) was induced in preadipocytes during differentiation. In the presence of GH, which markedly inhibited triglyceride accumulation, no reduction in the expression level of ADD1 was observed in response to GH, whereas there was a 50% reduction in the expression of PPARgamma. The DNA binding activity of the PPARgamma/retinoid X receptor-alpha(RXRalpha) to the ARE7 element from the aP2 gene was also reduced by approximately 50% in response to GH. GH inhibited the expression of late markers of adipocyte differentiation, fatty acid synthase, aP2, and hormone-sensitive lipase by 70-80%. The antiadipogenic effect of GH was not affected by the mitogen-activated protein (MAP) kinase/ extracellular-regulated protein (ERK) kinase inhibitor PD 98059, indicating that the mitogen-activated protein kinase pathway was not involved in GH inhibition of preadipocyte differentiation. The expression of preadipocyte factor-1/fetal antigen 1 was decreased during differentiation, and GH treatment prevented this down-regulation of Pref1/FA1. A possible role for Pref-1/FA1 in mediating the antiadipogenic effect of GH was indicated by the observation that FA1 inhibited differentiation as effectively as GH. These data suggest that GH exerts its inhibitory activity in adipocyte differentiation at a step after the induction of ADD1 but before the induction of genes required for terminal differentiation.

The clinical indications for identical pathogenesis of isolated and non-isolated testicular relapses in acute lymphoblastic leukaemia

In the present population-based study, we compared the clinical data of testicular relapses with and without concurrent bone marrow relapse and clinical data of the relapses in other locations among boys with acute lymphoblastic leukaemia (ALL), in order to study the possible evidence of early sequestration and local regulation of leukaemic lymphoblast in the testis of humans. The results suggest that the pathogenesis of isolated testicular relapse (T) and testicular relapse with a concurrent bone marrow relapse (T + BM) is likely to be similar. Isolated and non-isolated testicular relapses appeared late after the achievement of remission (T 34 +/- 16 months, T + BM 32 +/- 15 months) in ALL compared to relapses in other locations (CNS 23 +/- 11 months, BM 25 +/- 19 months). The better prognosis after testicular relapses (estimated second event free survival probability, 2-EFS: T 0.63, T + BM 0.32) compared to bone marrow relapse (2-EFS: BM 0.13) further suggests that testicular relapse with a concurrent bone marrow relapse possibly originates from the isolated testicular relapse, and that the isolated testicular relapse is a separate entity and not a manifestation of systemic recurrence. Higher frequencies of isolated and non-isolated testicular relapses (T 9%, T + BM 5%) were observed among boys with onset of ALL in early puberty (10-12 y) compared to those among younger (T 4%, T + BM 2%) and older (T 0%, T + BM 0%) boys. The late occurrence, the possible association with hormonal maturation and the good prognosis after testicular relapses suggest a possible local regulation of the residual leukaemic lymphoblast in human testis.

Growth hormone treatment of short children born small-for-gestational-age: the Nordic Multicentre Trial

The aims of this study were to evaluate the efficacy and safety of different doses of growth hormone (GH) treatment in prepubertal short children born small-for-gestational-age (SGA). Forty-eight children born SGA from Sweden, Finland, Denmark and Norway were randomly allocated to three groups: a control group of 12 children received no treatment for 2 y, one group was treated with GH at 0.1 IU/kg/d (n=16), and one group was treated with GH at 0.2 IU/kg/d (n=20). In total 42 children completed 2 y of follow-up, and 24 children from the treated groups completed 3 y of treatment. Their mean (SD) age at the start of the study was 4.69 (1.61) y and their mean (SD) height was -3.16 (0.70) standard deviation scores (SDS). The children remained prepubertal during the course of the study. No catch-up growth was observed in the untreated group, but a clear dose-dependent growth response was found in the treated children. After the third year of treatment, the group receiving the higher dose of GH, achieved their target height. The major determinants of the growth response were the dose of GH used, the age at the start of treatment (the younger the child, the better the growth response) and the family-corrected individual height deficit (the higher the deficit, the better the growth response). Concentration of insulin-like growth factor-I (IGF-I) and IGF-binding protein-3 increased during treatment. An increase in insulin levels was found without negative effects on fasting glucose levels or glycosylated haemoglobin levels. GH treatment was well tolerated. In conclusion, short prepubertal children born SGA show a dose-dependent growth response to GH therapy, and their target height SDS can be achieved within 3 y of treatment given GH at 0.2 IU/kg/d. However, the long-term benefit of different regimens of GH treatment in children born SGA remains to be established.

Long-term survival and quality of life in patients treated with a national all protocol 15-20 years earlier: IDM/HDM and late effects?

In a follow-up matched control study the 93 (70.5%) survivors of 132 children treated with a national protocol for acute lymphoblastic leukemia (ALL) and 5 survivors of the other 21 cases of ALL in childhood diagnosed in the same period were evaluated. Thus it was also a population-based study. The national treatment protocol was used in the period 1975-1980. Methotrexate (MTX) infusions combined with intrathecal MTX were used as prophylaxis against neuroleukemia instead of irradiation. Neither doxorubicin (Adriamycin) nor cyclophosphamide was used in the protocol. A questionnaire covering demographic data, number of offspring, learning problems, level of athletic performance, education, and work status as well as medical information was used. Forms were received from 94 (96%) of the 98 adult surviving cases and corresponding controls in the family. Interviews were performed in the remaining four cases (4%). There were no statistical differences between the two groups with respect to physical and mental health and quality of life. Hospital records of all patients were also checked for possible late effects. There was no definite case of secondary malignant neoplasm; however, there was one case of prolactinoma and only one case of serious sequelae (hemiparesis during therapy), probably due to intrathecal and intravenous MTX.

Sustained-release metoclopramide plus methylprednisolone versus placebo plus methylprednisolone as antiemetic prophylaxis during non-cisplatin chemotherapy. A randomized double-blind cross-over trial

In a randomized double-blind cross-over trial, sustained-release metoclopramide (S) plus methylprednisolone (M) was compared with placebo (P) plus methylprednisolone as antiemetic prophylaxis during two cycles of non-cisplatin chemotherapy. S was administered as 60 mg every 12 h commencing on the evening before chemotherapy up to total of 300 mg metoclopramide in 2.5 days. Evaluation of nausea and vomiting was done by self-assessment schemes and visual analog scales. Fifty patients were included and 36 fulfilled both cycles. Mild nausea and vomiting were experienced by 81% and 83% in the S + M and P + M groups, respectively, while 42% and 39% showed complete control of nausea and vomiting during the first day of treatment. Moderate-dose S did not add to the antiemetic efficacy of M in non-cisplatin chemotherapeutic regimens.

Very low density lipoprotein receptor binds and mediates endocytosis of urokinase-type plasminogen activator-type-1 plasminogen activator inhibitor complex

Very low density lipoprotein receptor (VLDL-R) was found to be expressed in bovine mammary gland and the human breast carcinoma cell line MCF-7 as an M(r) 105,000 variant, and in Chinese hamster ovary (CHO) cells transfected with human VLDL-R cDNA as an M(r) 130,000 variant. The receptor was purified by ligand affinity chromatography with immobilized M(r) 40,000 receptor-associated protein (RAP). The purified receptor was found to bind urokinase-type plasminogen activator-type-1 plasminogen activator inhibitor complex (u-PA.PAI-1), while there was no or very weak binding of active site blocked u-PA (DFP-u-PA), PAI-1 or u-PA-type-2 plasminogen activator inhibitor complex. The binding of u-PA.PAI-1 was blocked by RAP. The transfected CHO cells had an efficient, RAP-sensitive endocytosis of u-PA.PAI-1, severalfold higher than non-transfected parental CHO cells. u-PA.PAI-1 endocytosis was partially inhibited by DFP-u-PA, which blocks binding of the complex to the u-PA receptor. RAP and DFP-u-PA sensitive u-PA.PAI-1 endocytosis was also observed in MCF-7 cells, which were without detectable levels of other RAP-binding endocytosis receptors. These results show that VLDL-R represents a novel endocytosis mechanism for u-PA receptor-bound u-PA.PAI-1.

[Information to cancer patients prior to participation in clinical trials. Evaluation of a structured information program]

Informing patients before starting of antineoplastic treatment is important due to the legal aspects of clinical trials and the anxiety and uncertainty felt by the patients. This study evaluates a structured information programme used in a clinical trial. Thirty-four women were interviewed three months after receiving information about trial, using a tape-recorded structured interview. Results showed that the information was well remembered. The patients were glad to have brought a relative to the two consultations, and the time for deliberation in between was well received. The patients viewed written information as an important source of reinformation. The information provided was positively evaluated. Open and detailed information did not undermine the doctor-patient relationship. Instead it allowed patients to understand and participate in treatment decision and helped to reduce their pre-therapy anxiety and uncertainty. The results support expanding structured information programmes to include not only those patients asked to participate in the clinical trial, but all patients beginning longlasting cancer therapy.

Tyrosine metabolism in users of oral contraceptives

Brain noradrenaline takes part in the regulation of several brain functions. The formation of brain noradrenaline depends on brain tyrosine (Tyr) levels, which associates with the ratio in plasma of Tyr to other large, neutral amino acids (LNAA). Tyr metabolism has been studied in users of the new generation combined oral contraceptives (OC) and comparable controls at the follicular, mid-cycle, and luteal phases of the menstrual cycle. OC users showed significantly increased plasma Tyr transaminase activity, and significantly decreased plasma Tyr and Tyr/LNAA levels at mid-cycle and luteal phase, whereas plasma total 3-methoxy-4-hydroxyphenylglycol (MHPG) was not affected. Following an oral protein load, the area under the curve in plasma of Tyr and Tyr/LNAA in OC users at the luteal phase were 43% and 29%, respectively, of control levels. The results suggest that the decreased Tyr availability to the brain in OC users may result in a substrate-limited reduction of brain noradrenaline formation, which, secondarily, may contribute to disturbances of mood, coping mechanisms, and appetite in susceptible subjects.

Endothelin in renovascular and essential hypertension

Immunoreactive endothelin (ir-ET) was measured in peripheral venous plasma in 12 patients with renovascular hypertension (RVH) due to unilateral renal arterial stenosis, in 12 patients with essential hypertension (EH), and in 12 control subjects (C). In the patients with RVH, ir-ET was also measured in the aorta and in both renal veins before and 1 h after 25 mg of captopril was given orally. In peripheral venous plasma, ir-ET was the same in RVH (median 1.02 pmol/l (range 0.53-1.65)) as in EH (0.96 pmol/l (0.76-1.32)) and in C (1.00 pmol/l (0.77-1.16)). In RVH, the concentrations of ir-ET decrease from the aorta to the renal vein of both the affected (0.88 pmol/l (0.54-1.28) vs 0.68 (0.51-1.24), p < 0.01) and in the unaffected kidney (0.85 pmol/l (0.62-1.38) vs 0.78 pmol/l (0.36-1.25), p < 0.01). Renal extraction of ir-ET was the same on the affected side (15.1% (-3.7-33.2)) and on the unaffected side (11.2% (0.5-46.4)). In the aorta, ir-ET was significantly lower than in peripheral venous plasma (p < 0.05). The renal handling of ir-ET did not change in response to captopril in either the affected or unaffected kidney. It is concluded that circulating levels of ir-ET are normal in renovascular hypertension associated with unilateral renal artery stenosis and in essential hypertension. There is significant renal extraction of ir-ET which is unaffected by renal artery stenosis and captopril.

Biofeedback treatment of children and adults with idiopathic detrusor instability

In adults and children suffering from urge, urge incontinence, frequent voidings, and nocturia, urodynamic examination often confirms the diagnosis of detrusor instability. We assessed the outcome of biofeedback therapy in 15 children aged 6-12 years and 7 adults aged 20-52 years, all with cystometrically proven detrusor instability. The detrusor pressure was visually conveyed to the patient during repeated bladder fillings. The patient was instructed to interrupt detrusor pressure increments by tensing the pelvic floor musculature. None of the children were found completely cured; however, 9 showed a marked decrease in either the number of the extent of symptoms. Two children showed moderate improvement, while 4 remained unaffected by the treatment. One adult was completely cured, 2 improved moderately, and 4 showed no improvement. None of these patients were converted to stable cystometry. Upon termination of the BF treatment a follow-up study was conducted for patients exhibiting pronounced or moderate improvement. The beneficial effect was maintained except in one case.

Effect of captopril on the renal veno-arterial gradient of erythropoietin and oxygen in unilateral renal artery disease

Twenty-nine patients with unilateral renal artery stenosis or occlusion were investigated. The veno-arterial gradient (VA-gradient) of erythropoietin (EPO), haemoglobin oxygen saturation and plasma renin activity (PRA) was determined separately in each kidney before and 1 h after angiotensin converting enzyme inhibition (ACE-inhibition). The VA-gradient of EPO and of hemoglobin oxygen saturation were the same in the affected and unaffected kidney during basal conditions. During ACE-inhibition the VA-gradient of EPO disappeared on the affected side but not on the unaffected side. A fall in s-EPO after ACE inhibition was demonstrated in the renal vein on the affected side (-1.4 U l-1, p < 0.01), in the contralateral vein (-0.8 U l-1, p < 0.01) and in the aorta (-0.6 U l-1, p < 0.01). The O2-gradients were reduced on both sides after captopril, from 10.8-7.5% (p < 0.04) on the affected side and from 10.8-9.0% (p < 0.04) on the contralateral. It is suggested that the stimulated renin-angiotensin system may be important for EPO production in the affected kidney in unilateral renal disease.

Urodynamic biofeedback training for children with bladder-sphincter dyscoordination during voiding

Neurologically normal children with recurrent urinary tract infections (UTIs), night- and daytime wetting, and urge and painful voiding may have staccato voiding due to pelvic floor contractions. The immediate effect of non-invasive urodynamic biofeedback (BF) therapy was assessed using a historical follow-up study in 31 children aged 5-15 years suffering from urodynamically proven overactive urethra during voiding. A long-term follow-up study was performed to investigate whether improvement was maintained. Twenty-four children (77.5%) benefited from the treatment. Of these 16 (51.5%) were cured, while 8 (26%) had a pronounced reduction in their symptoms. Although the flow was normalized in 17 (55%) and nearly normalized in 7 (22.5%), there was no significant correlation between subjective and objective criteria of improvement. Similarly, no relationship was found between the initial urodynamic characteristics and the treatment outcome. During a mean follow-up time of 4 years (range: 1-7.5 years) two of the initially cured patients relapsed. They were recurred with a refresher course. Three had had a single or a few episodes of cystitis in the course of several years. Of the patients with pronounced reduction in their symptoms, three relapsed. A refresher course was attempted in two patients; one was successful. It can thus be concluded that BF is an effective way of treating this disturbance and the beneficial effect is to a wide degree maintained.

Information for cancer patients entering a clinical trial--an evaluation of an information strategy

Informing patients before the start of antineoplastic treatment is important due to the anxiety and uncertainty felt by the patients and the legal aspects of trials. 34 women were interviewed 3 months after receiving information. Results show that the information was well remembered, patients were glad to bring a relative, two consultations with time for deliberation were well-received and that patients viewed written information as an important reinforcement. Overall, information provided was positively evaluated. Detailed information allowed patients to understand and participate in treatment decisions, thereby reducing their pretherapy anxiety. These results support expansion of the structured information programme to include all patients about to begin long-term cancer therapy.

Angiotensin-converting enzyme inhibitor renography in the diagnosis of renovascular hypertension. Studies before and after angioplasty

Renography with [99mTc] diethylenetriaminepenta-acetate (DTPA) was performed in 26 patients with renal artery stenosis (RAS), unilateral in 15 and bilateral in 11, and in 16 patients with essential hypertension with a normal renal angiogram. Nine of the patients with unilateral RAS were restudied after a successful percutaneous transluminal renal angioplasty (PTRA), i.e. complete removal of the stenosis and a normalization of the blood pressure without antihypertensive treatment. Single-kidney [99mTc]-DTPA clearance and parenchymal mean transit time (MTT) were determined at each examination. All patients were studied on two different days using the same procedure except that captopril 25 mg was given orally before renography at the second examination. In unilateral RAS captopril reduced single-kidney [99mTc]-DTPA clearance significantly on the affected side (-42.7%, median) but not on the unaffected side (-3.2%). In bilateral RAS single-kidney [99mTc]-DTPA clearance was reduced to the greatest extent on the most affected side (-43.0%) compared with the least affected side (-17.2%). In essential hypertension no significant changes were recorded on any side (-1.5% for both). After PTRA, single-kidney [99mTc]-DTPA clearance was not significantly changed by captopril either on the previously affected side (4.3%) or on the unaffected side. MTT was significantly prolonged after captopril on the affected side in unilateral RAS and on the most affected side in bilateral RAS, whereas no significant changes were found on the unaffected side in unilateral RAS, on the least affected side in bilateral RAS, or on any side in essential hypertension.(ABSTRACT TRUNCATED AT 250 WORDS)

[Percutaneous embolization of vascular abnormalities]

In six male patients, percutaneous embolisation of symptom-producing vascular anomalies was performed with spirals or small particles. After a total of ten treatments, symptom-free states were obtained in half of the patients and definite improvement in the remainder. The results are so promising that this method of treatment will be continued.

Differentiation between renovascular and essential hypertension by means of changes in single kidney 99mTc-DTPA clearance induced by angiotensin-converting enzyme inhibition

Blood pressure (BP), plasma renin concentration (PRC), and 99mTc-labeled diethylenetriaminepenta acetate (DTPA) renography with determination of single kidney 99mTc-DTPA clearance and parenchymal mean transit time (MTT) were measured in exactly the same way on two consecutive days in 14 patients with renovascular hypertension (RVH), unilateral renal artery stenosis in nine and bilateral stenosis in five, and ten patients with essential hypertension (EH). The examination on day 1 served as a control for day 2 during which captopril (25 mg) was given orally one hour before measurements of PRC and DTPA clearance. Blood pressure was reduced by captopril in both groups, but the maximum decrease in systolic BP was slightly more pronounced (P less than .01) in RVH (22%, median) than EH (13%). Plasma renin concentration increased to a much greater extent (P less than .01) after captopril in RVH (366%) than in EH (46%), Single kidney 99mTc-DTPA clearance was significantly (P less than .01) reduced (-39.5%) and MTT considerably prolonged (170%) on the affected/most affected side in RVH, but both parameters were only slightly changed or unchanged on the unaffected/least affected side (-6.5%, -2% respectively) and were not significantly changed in any of the sides in EH. The degree of renal artery stenosis was significantly correlated to the increase in PRC (rho = -0.786, n = 14 patients, P less than .01), to the reduction in single kidney 99mTc-DTPA clearance (rho = 0.729, n = 19 kidneys, P less than .01) and to the prolongation in MTT (rho = -0.785, n = 16 kidneys, P less than .01). By analysis of the captopril-induced changes in 99mTc-DTPA clearance and MTT, it was possible to predict the existence of a moderate to several renal artery stenosis in arterial hypertension with a very high degree of probability, and the use of changes in 99mTc-DTPA clearance and MTT after angiotensin-converting enzyme (ACE) inhibition may become a valuable tool in differentiation between RVH and EH.

Abnormal glomerular and tubular function during angiotensin converting enzyme inhibition in renovascular hypertension evaluated by the lithium clearance method

Glomerular filtration rate (GFR) and tubular function were measured by means of the lithium clearance technique in 14 patients with renovascular hypertension (RVH) and eight patients with essential hypertension (EH) before and after oral administration of captopril 25 mg. In RVH captopril reduced 51-Cr-EDTA clearance (67.3 (median) to 47.5 ml min-1, P less than 0.01), proximal absolute reabsorption of fluid (53.9 to 41.5 ml min-1, P less than 0.01) and distal absolute reabsorption of sodium (2195 to 1402 mumol min-1, P less than 0.01), whereas proximal fractional reabsorption increased slightly (77.5 to 80.2%, P less than 0.02). In EH, however, these parameters were practically unaffected by captopril. In both RVH and EH plasma concentrations of angiotensin II and aldosterone were reduced after captopril, but atrial natriuretic peptide in plasma and urinary excretion rate of prostaglandin E2 were unchanged. Blood pressure decreased after captopril in both groups, but the maximum fall in systolic BP was more pronounced in RVH (22%) than EH (13%). It is concluded that angiotensin converting enzyme inhibition markedly reduced absolute reabsorption in both the proximal and distal tubules in RVH, in contrast to EH, predominantly due to fall in the GFR, and that the slight increase in proximal fractional reabsorption may be attributed to a reduction in the hydrostatic pressure in the peritubular vessels.

Development of more potent atrial natriuretic factor (ANF) analogs

Four modified atrial natriuretic factor (ANF) analogs were designed and synthesized by the solid-phase method. Using human ANF-(99-126) as the reference compound the receptor binding affinity and biological activity of these analogs were examined by radioreceptor assay and in vivo experiments. PLO68, a 21 amino peptide with structural modifications des-Ser103,104-[Mpr105,D-Ala107,114]APII-amide exhibited 2.5 and 2.2 fold more activity than human ANF-(99-126) in lowering blood pressure and causing natriuresis in urethane anesthetized rats. Receptor binding assays using rat lung membranes showed that PLO68 had a Kd of 200 +/- 12 pM compared to a Kd of 620 +/- 12 pM for human ANF-(99-126). Similar chemical modifications, except for substitution of glycine and alanine at the positions 115 and 118, and 120 by D-alanine resulted in three analogs PLO63 and PLO64, PLO67 respectively. PLO63, PLO64 and PLO69 had similar affinities and in vivo potency as human ANF-(99-126). These data suggest that the structural modifications made in PLO68 can cause an increase in the receptor binding ability and an enhancement of biological activities.