A novel modified pterin from a Eudistoma species ascidian.

The MeOH extract of an Indonesia Eudistoma sp. ascidian contained 1,3,O(7)-trimethylisoxanthopterin (1), a novel pteridine. The purification of 1 was achieved through flash C(18) chromatography and cyano HPLC. The structure was determined primarily through the use of (1)H-(13)C and (1)H-(15)N HMBC measurements and comparison with data obtained for 1,3,7-trimethylguanine (2).

Single amino acid substitutions in kappa-conotoxin PVIIA disrupt interaction with the shaker K+ channel.

kappa-Conotoxin PVIIA (kappa-PVIIA), a 27-amino acid peptide with three disulfide cross-links, isolated from the venom of Conus purpurascens, is the first conopeptide shown to inhibit the Shaker K(+) channel (Terlau, H., Shon, K., Grilley, M., Stocker, M., Stühmer, W., and Olivera, B. M. (1996) Nature 381, 148-151). Recently, two groups independently determined the solution structure for kappa-PVIIA using NMR; although the structures reported were similar, two mutually exclusive models for the interaction of the peptide with the Shaker channel were proposed. We carried out a structure/function analysis of kappa-PVIIA, with alanine substitutions for all amino acids postulated to be key residues by both groups. Our data are consistent with the critical dyad model developed by Ménez and co-workers (Dauplais, M., Lecoq, A., Song, J. , Cotton, J., Jamin, N., Gilquin, B., Roumestand, C., Vita, C., de Medeiros, C., Rowan, E. G., Harvey, A. L., and Ménez, A. (1997) J. Biol. Chem. 272, 4802-4809) for polypeptide antagonists of K(+) channels. In the case of kappa-PVIIA, Lys(7) and Phe(9) are essential for activity as predicted by Savarin et al. (Savarin, P., Guenneugues, M., Gilquin, B., Lamthanh, H., Gasparini, S., Zinn-Justin, S., and Ménez, A. (1998) Biochemistry 37, 5407-5416); these workers also correctly predicted an important role for Lys(25). Thus, although kappa-conotoxin PVIIA has no obvious sequence homology to polypeptide toxins from other venomous animals that interact with voltage-gated K(+) channels, there may be convergent functional features in diverse K(+) channel polypeptide antagonists.

Trypargine alkaloids from a previously undescribed Eudistoma sp. ascidian.

The MeOH extract of an undescribed Eudistoma sp. ascidian was found to contain the known beta-carboline trypargine (3); the two novel trypargine derivatives trypargimine (4) and 1-carboxytrypargine (5); and 3',5'-dibromo-4'-methoxyphenethylamine (6). The structures of the novel trypargine derivatives were elucidated through the use of mass spectrometry and NMR. The trypargine isolated in this study was found to be nearly racemic in contrast to the previously described isolate which was chiroptically pure. Other previously described compounds detected in the MeOH extract include 4-hydroxyphenylacetamide, tryptamine, 1,3,7-trimethylguanine, and tetrahydropentoxyline (7).

Reversible membranous nephropathy associated with the use of nonsteroidal anti-inflammatory drugs.

OBJECTIVE: To investigate the frequency of membranous nephropathy associated with nonsteroidal anti-inflammatory drug (NSAID) use and identify associated clinical characteristics. DESIGN: Retrospective chart review. SETTING: A large group practice that staffs 2 large teaching hospitals. PATIENTS: All patients diagnosed as having stage I or early stage II membranous nephropathy by renal biopsy between January 1975 and May 1995. MAIN OUTCOME MEASURES: Nephrotic syndrome was said to be associated with NSAID use if patients developed nephrotic syndrome while taking an NSAID and if other causes of membranous nephropathy were excluded and a rapid remission of the nephrotic syndrome followed withdrawal of the drug. RESULTS: Of 125 patients identified with early membranous nephropathy, 29 were taking NSAIDs at the time symptoms of nephrotic syndrome developed. Thirteen of these patients met the criteria for NSAID-associated membranous nephropathy. None of these patients had any evidence of renal insufficiency or significant proteinuria after follow-up periods ranging from 5 months to 13 years. In addition to diclofenac and fenoprofen, which have previously been implicated, ibuprofen, nabumetone, naproxen, and tolmetin were found to be associated. CONCLUSIONS: Nephrotic syndrome due to membranous nephropathy should be recognized as an idiosyncratic drug reaction to many NSAIDS. Because withdrawal of the drug may result in prompt and complete recovery of normal renal function, a history of NSAID intake should be sought in patients with membranous nephropathy.

Hemolytic uremic syndrome after bone marrow transplantation without total body irradiation.

The cause of hemolytic uremic syndrome after bone marrow transplantation is unknown. Investigators have implicated multiple causes, including cyclosporin A, graft versus host disease, cytomegalovirus infection, and total body irradiation. We report a case of biopsy-supported hemolytic uremic syndrome in a recipient of an autologous bone marrow transplant who did not receive total body irradiation or cyclosporin A and did not have clinical evidence of cytomegalovirus infection. This case casts doubt on the hypothesis that irradiation or any of these factors is the sole and universal cause of hemolytic uremic syndrome in patients receiving bone marrow transplants.

Risk factors in idiopathic renal vasculitis and glomerulonephritis.

In this retrospective study, we analyzed clinical laboratory, and pathologic variables to determine their value in predicting survival and survival free of renal failure for 170 consecutive patients with idiopathic renal vasculitis and glomerulonephritis evaluated during a 15 year period. Of the 170 patients, 108 had focal segmental necrotizing glomerulonephritis alone (FSNGN), 33 had FSNGN and small-artery vasculitis, and 29 had FSNGN and medium-sized artery vasculitis. Considerable overlap of clinical, laboratory, and pathologic findings existed among the three groups. Overall patient survival was 81% at one year, 61% at five years, and 44% at ten years, significantly less than expected survival. Overall survival free of renal failure, by definition, was lower than patient survival. There were no differences among these three groups in patient survival or survival free of renal failure. Multivariate analysis identified leukocytosis and serum creatinine level as independent predictors of patient survival and survival free of renal failure. In addition, univariate analysis identified age and hypertension as significant risk factors but did not add independent predictive value for these two end points. In patients with serum creatinine levels less than 4 mg/dl, the effect of increasing levels of leukocyte count was significantly associated with poorer outcomes for both patient survival (P = 0.006) and survival free of renal failure (P = 0.024). Outcomes for these two end points were worse for patients with lower serum creatinine levels (less than 4.0 mg/dl) and high leukocyte counts (greater than 16,000/mm3) than for those with serum creatinine levels greater than or equal to 4.0 mg/dl.

Is the priming principle both effective and safe?

This study determined the priming dose of vecuronium (V), pancuronium (P) and atracurium (A) that resulted in the most rapid onset of neuromuscular blockade (NMB) in 150 patients given either V 0.08 mg/kg, P 0.1 mg/kg or A 0.6 mg/kg. Patients were further divided (n = 10 per group) to receive no prime or 5%, 10%, 15% or 20% of the total dose as a prime followed 5-7 minutes later by the remaining (intubating) dose. A further 10 patients received 0.04 mg/kg d-tubocurarine followed by 1.5 mg/kg succinylcholine (S). Priming significantly shortened the onset of NMB. The priming doses producing the most rapid onset were 0.012 mg/kg for V, 0.015 mg/kg for P and 0.09 mg/kg for A. The S resulted in significantly greater NMB at 60 sec than any priming dose of A, V or P. There was no difference between the three nondepolarizing neuromuscular blockers in shortening the onset of NMB produced by priming. To evaluate both the effect of the "optimal" priming dose in awake patients and the effect of increasing intubating doses on NMB an additional 40 patients were given V 0.012 mg/kg followed by V 0.08, 0.1, 0.12 or 0.15 mg/kg. Increasing the intubating dose did not improve onset of NMB. The "optimal" priming dose, however, resulted in a high incidence of symptoms of muscle weakness. We conclude that priming shortens the onset of NMB similarly between V, P and A but the priming dose producing the most rapid onset of NMB also results in a high incidence of side effects and therefore the priming principle should be used with caution.

Idiopathic membranous nephropathy: the natural history of untreated patients.

We reviewed the diagnostic features and clinical course of 140 patients with idiopathic membranous nephropathy who had their index renal biopsies performed at the Mayo Clinic between 1972 and 1984. There were 93 males and 47 females (average age, 50.8 +/- 17 years); 116 patients (83%) had the nephrotic syndrome and 42 (30%) were hypertensive at diagnosis. Eighty-nine patients were not treated with corticosteroid or immunosuppressive drugs and 51 patients were treated mainly with short-term courses of prednisone alone; a minority of patients also received meclofenamate, cyclophosphamide, azathioprine, or chlorambucil. Five-year survival, including patients who received dialysis or a renal transplant, was 85%, 75% at 10 years, and no different from expected survival; there was no difference between untreated and treated groups. Also, there were no differences in the outcomes of renal function and protein excretion between untreated and treated patients. Among 28 patients (20%) who developed end-stage renal disease, 17 showed rapid progression within 2.5 years after diagnosis. Fifteen of the 17 patients were males; all were severely nephrotic and had impaired renal function at diagnosis. Only 1 of 24 patients with nonnephrotic proteinuria at index renal biopsy progressed to end-stage renal disease. Overall, a level of baseline proteinuria of 10 g or more per 24 hours and variable blood pressure control in hypertensive patients were associated with renal progression.

Renal involvement in relapsing polychondritis.

Twenty-nine of the 129 patients with RP seen at the Mayo Clinic between 1943 and 1984 had renal involvement. These patients were older, had arthritis and extrarenal vasculitis more frequently, and had a significantly worse survival rate than those without renal involvement. Renal biopsies were obtained in 11 of these 29 patients. The predominant lesions were mild mesangial expansion and cell proliferation, and segmental necrotizing glomerulonephritis with crescents. Small amounts of electron-dense deposits, predominantly mesangial, were noted on electron microscopy. Immunofluorescence revealed faint deposition of C3 and/or IgG or IgM, predominantly in the mesangium. Autopsies were obtained in 13 of the 47 patients who had died. Information regarding the renal pathology was available in 10 of these 13 autopsies. At the time of the initial evaluation at the Mayo Clinic, 6 of these 10 patients had evidence of renal involvement. At autopsy, none of these 10 patients had evidence of active renal vasculitis or segmental necrotizing glomerulonephritis, but 8 of the 10 patients exhibited variable degrees of vascular and glomerular sclerosis, segmental mesangial proliferation, tubular loss, and interstitial lymphocytic infiltrates. These observations expand the limited information available in the literature, which is based on 11 previously published case reports of renal involvement in RP. In only a few of our patients and previously reported patients were the manifestations of the disease limited to the systems characteristically involved in pure RP. The frequent coexistence of other autoimmune and connective tissue diseases supports the role of immune mechanisms in the pathogenesis of this syndrome. Deposition of immune complexes is likely to play a role in the pathogenesis of the glomerular lesions associated with RP. Administration of corticosteroids alone is sufficient to induce a complete remission in some cases, while in others the addition of a cytotoxic agent is necessary to control the activity of the disease or to spare corticosteroid side effects and maintain a remission. Immunosuppression-related infectious complications and undetected relapses after discontinuation of immunosuppressive therapy are largely responsible for the morbidity and mortality observed in these patients.

Distribution and uptake of helium, carbon monoxide, and acetylene in the lungs during high frequency oscillatory ventilation.

In order to obtain a better understanding of intrapulmonary gas mixing and alveolar-capillary gas transport during high frequency oscillatory ventilation (HFO), we measured insoluble gas (He) equilibration, and soluble gas (CO, C2H2) uptake in the lungs of ten anesthetized dogs during closed system HFO (i.e. no fresh gas bias flow). These gases were introduced as a bolus into the lumen of an endotracheal tube and their concentrations were subsequently measured for 20-25 sec from a catheter in the distal end of this tube. Analysis of He concentrations over time was performed using a two compartment series model to calculate a value for effective ventilation (Veff). This Veff was found to range from 0.83 to 23.8 L/min and was directly related to oscillator output (f X VT product, r = 0.77). Analysis of CO and C2H2 concentrations during HFO using a similar two-compartment model having alveolar capillary gas transport in series with Veff allowed for the calculation of pulmonary capillary blood flow (QHFO) and lung diffusing capacity (DHFO). These values for QHFO were found to be not significantly different from simultaneous thermodilution determinations of cardiac output and these values for DHFO were found to be not significantly different from single breath or rebreathing determinations of CO diffusing capacity. Moreover, QHFO and DHFO did not vary with Veff. We conclude that this two compartment in series model is a reasonable way to characterize insoluble and soluble gas behavior during HFO, that Veff is related to oscillator output, and that QHFO and DHFO are not affected by HFO over the range of Veff studied.

Treatment of severe nephrotic syndrome with meclofenamate: an uncontrolled pilot study.

The effect of meclofenamate on urinary protein excretion, level of serum albumin, and renal function was studied prospectively in 30 patients with corticosteroid-resistant severe nephrotic syndrome: 16 with focal segmental glomerulosclerosis, 12 with membranous glomerulopathy, and 2 with minimal-lesion nephropathy. Seventeen patients had a 40% or more reduction in urinary protein excretion ("responders"), and the decrease continued during long-term treatment. Meclofenamate therapy was discontinued after 2 months in eight "nonresponders" and in five other patients because of side effects (progressive increase in the level of serum creatinine in two, diarrhea in two, and pruritus in one). In responders, we recorded the following findings (mean +/- SD): urinary protein excretion decreased from 13.0 +/- 5.2 g/24 h to 7.2 +/- 3.5 g/24 h in 2 to 4 weeks and continued to decrease to 4.1 +/- 1.4 g/24 h at the time of the last follow-up study (median duration, 12 months; range, 6 to 36 months; P less than 0.01, 2 to 4 weeks versus later follow-up); the level of serum albumin increased from 1.9 +/- 0.5 g/dl to 2.9 +/- 0.7 g/dl (P less than 0.001) in 2 to 4 weeks; the level of serum cholesterol decreased from 413 +/- 125 mg/dl to 346 +/- 114 mg/dl (P less than 0.005) at the time of the last follow-up examination; and renal function remained unchanged from the baseline study to the follow-up study (serum creatinine 1.5 +/- 0.5 mg/dl versus 1.6 +/- 0.4 mg/dl and glomerular filtration rate 60.5 +/- 29.2 ml/min per 1.7 m2 versus 64.1 +/- 25.5 ml/min per 1.7 m2).(ABSTRACT TRUNCATED AT 250 WORDS)

Endoscopic evaluation and treatment of patients with idiopathic gross hematuria.

We evaluated 4 patients with long-standing unilateral essential gross hematuria by newer endourological techniques. All 4 patients underwent ureterorenoscopy and 3 underwent percutaneous nephroscopy. Nephroscopy identified a bleeding site in 3 patients and ureteroscopy in 1. The bleeding sites were fulgurated and the hematuria has not recurred during followup. Percutaneous nephroscopy and/or ureterorenoscopy should be considered in selected patients with unilateral essential gross hematuria.

Renal vein thrombosis in idiopathic membranous glomerulopathy and nephrotic syndrome: incidence and significance.

The point prevalence and clinical significance of renal vein thrombosis (RVT) was evaluated in 27 of 33 consecutive nephrotic patients with idiopathic membranous glomerulopathy. A technique of retrograde venography after the injection of epinephrine into the main renal artery to decrease renal blood flow was used. Two patients had histories compatible with a thromboembolic event, and the excretory urogram was not suggestive of RVT in any patient. RVT was noted in 13 patients; in eight it was bilateral. All patients with RVT received anticoagulant drugs for a minimum of 1 year after the study, and no thromboembolic events occurred in this group. No patient was treated with corticosteroids. Follow-up observation of an average of 2.5 years has not revealed a significant difference in the rate of renal function deterioration or change in degree of proteinuria between patients with and without RVT. Coagulation abnormalities included elevated platelet counts and plasma fibrinogen levels and prolonged reptilase and thrombin times. These were noted in all 14 patients studied, six of whom had RVT. In patients experiencing a nephrotic remission, coagulation abnormalities reverted to normal. RVT is common in idiopathic membranous glomerulopathy with nephrosis and is associated with few clinical markers. Its influence on renal function and proteinuria is of questionable significance. Coagulation abnormalities may be a causative factor of RVT in this setting.

Pharmacokinetics of verapamil: experience with a sustained intravenous infusion regimen.

Disappearance kinetic characteristics of verapamil were determined in 9 patients after a single intravenous dose. From the pharmacokinetic variables determined, we designed an intravenous regimen to maintain a plasma verapamil concentration of 150 ng/ml consisting of (1) a loading bolus (10 mg over 2 minutes), followed by (2) a rapid loading infusion (0.375 mg/min) for 30 minutes, and finally (3) a maintenance infusion (0.125 mg/min). We tested this regimen in 7 patients for 2 to 12 hours, and found it to be safe and to produce stable prolongation of the P-R interval. Verapamil concentration was highest immediately after the bolus administration and was prevented from falling below 67 ng/ml by the rapid infusion. Maintenance concentration remained between 77 and 156 ng/ml for all patients, and averaged 122 ng/ml. Transient and slight decreases in brachial blood pressure and sinus cycle length occurred coincident with the maximum verapamil concentration. Maximum P-R prolongation lagged behind peak plasma concentration but was sustained for the duration of the infusion. Prolongation of the P-R interval was not significantly different at the end of the infusion from that 90 minutes after the start of the regimen. No patient demonstrated significant side effects, arrhythmia, or clinically important hypotension. Although the specified regimen produced a final concentration averaging 125 ng/ml, it is predicted that infusion regimens producing other plasma concentrations can be similarly devised by changing the bolus, rapid loading infusion, and maintenance infusion doses in proportion to the desired final plasma concentration.

Primary systemic amyloidosis: resolution of the nephrotic syndrome with melphalan and prednisone.

We describe two patients with primary systemic amyloidosis (AL) and the nephrotic syndrome. The administration of melphalan and prednisone was associated with resolution of the nephrotic syndrome. The serum albumin level returned to normal, proteinuria decreased to near normal, edema resolved, and the monoclonal protein in the serum and urine disappeared. In both patients, renal function remained stable and hepatomegaly disappeared. In both, however, amyloid deposition was greater in follow-up renal tissue than in the initial specimen. The effect of systemic therapy in AL must be assessed with histologic observations as well as clinical indexes.