Test for cooperativity in the early kinetic intermediate in lysozyme folding.

During the folding of many proteins, collapsed globular states are formed prior to the native structure. The role of these states for the folding process has been widely discussed. Comparison with properties of synthetic homo and heteropolymers had suggested that the initial collapse represented a shift of the ensemble of unfolded conformations to more compact states without major energy barriers.

Transient dimer in the refolding kinetics of cytochrome c characterized by small-angle X-ray scattering.

The equilibrium unfolding and the kinetic refolding of cytochrome c (Cyt c) in the presence of imidazole were studied with small-angle X-ray scattering (SAXS). The equilibrium unfolding experiments showed the radius of gyration, R(g), of native Cyt c to swell approximately 1 A with the addition of imidazole. The thermodynamic parameter m also reflects an expansion of the protein as its lower value demonstrates an increase in solvent-accessible surface area over that of native Cyt c in the absence of imidazole.

Chain collapse can occur concomitantly with the rate-limiting step in protein folding.

We have directly characterized the extent of chain collapse early in the folding of protein L using time-resolved small angle X-ray scattering. We find that, immediately after the initiation of refolding, the protein exhibits dimensions indistinguishable from those observed under highly denaturing, equilibrium conditions and that this expanded initial state collapses with the same rate as that of the overall folding reaction. The observation that chain compaction need not significantly precede the rate-limiting step of folding demonstrates that rapid chain collapse is not an obligatory feature of protein folding reactions.

Characterization of transient intermediates in lysozyme folding with time-resolved small-angle X-ray scattering.

We have used synchrotron radiation, together with stopped-flow and continuous-flow mixing techniques to monitor refolding of lysozyme at pH 5.2. From data measured at times which range from 14 ms to two seconds, we can monitor changes in the size, the shape and the pair distribution function of the polypeptide chain during the folding process.

Association of partially-folded intermediates of staphylococcal nuclease induces structure and stability.

Staphylococcal nuclease forms three different partially-folded intermediates at low pH in the presence of low to moderate concentration of anions, differing in the amount of secondary structure, globularity, stability, and compactness. Although these intermediates are monomeric at low protein concentration (< or =0.25 mg/mL), increasing concentrations of protein result in the formation of dimers and soluble oligomers, ultimately leading to larger insoluble aggregates.

Protein denaturation: a small-angle X-ray scattering study of the ensemble of unfolded states of cytochrome c.

Solution X-ray scattering was used to study the equilibrium unfolding of cytochrome c as a function of guanidine hydrochloride concentration at neutral pH. The radius of gyration (Rg) shows a cooperative transition with increasing denaturant with a similar Cm to that observed with circular dichroism. However, the lack of an isoscattering point in the X-ray scattering patterns suggests the equilibrium unfolding is not simply a two-state process.

Anion-induced folding of Staphylococcal nuclease: characterization of multiple equilibrium partially folded intermediates.

The refolding of acid-unfolded staphylococcal nuclease (SNase) induced by anions was characterized, and revealed the existence of three different partially folded intermediates (A states). The three intermediates lack the rigid tertiary structure characteristic of native states, and differ in their degree of folding as measured by probes of secondary structure, size, stability and globularity. The least structured conformation, A1, is stabilized by chloride (600 mM) or sulfate (100 mM).

Association-induced folding of globular proteins.

It has generally been assumed that the aggregation of partially folded intermediates during protein refolding results in the termination of further protein folding. We show here, however, that under some conditions the association of partially folded intermediates can induce additional structure leading to soluble aggregates with many native-like properties. The amount of secondary structure in a monomeric, partially folded intermediate of staphylococcal nuclease was found to double on formation of soluble aggregates at high protein or salt concentrations.

Sustained remission of membranous glomerulonephritis after cyclophosphamide and prednisone.

Objective: To determine the effect of cyclophosphamide and prednisone on progressive renal failure and on nephrotic features in patients with membranous glomerulonephritis.

Design: Prospective, nonrandomized time series.

Setting: Outpatient clinic at a university medical center.

Long-term follow-up of aggressively treated idiopathic rapidly progressive glomerulonephritis.

Purpose: We wanted to examine the long-term effects of aggressively treating idiopathic rapidly progressive glomerulonephritis (RPGN), with a particular focus on clinically characterizing the patient population, assessing the short- and long-term effects of therapy on renal function, and determining complications of the therapy.

Patients And Methods: Twenty-three consecutive patients with RPGN were treated and followed from one to 11 years. On renal biopsy, 13 had immune complexes, eight had no immune complexes, and two had antiglomerular basement membrane deposits.

Rupture of ovarian cyst: massive hemoperitoneum in continuous ambulatory peritoneal dialysis patients: diagnosis and treatment.

Two women on continuous ambulatory peritoneal dialysis (CAPD) developed recurrent episodes of hemoperitoneum while in the reproductive age group. Initially, both were thought to have mechanical problems with the peritoneal catheter system. A laparotomy was performed in the first patient, and a bleeding ovarian cyst was identified.

Genital edema in patients on continuous ambulatory peritoneal dialysis. Report of 3 cases and review of the literature.

Severe genital edema is a well-described complication of continuous ambulatory peritoneal dialysis (CAPD). Leakage of dialysate fluid from defects in the peritoneum may occur from clinically detectable and undetectable inguinal hernias, defects at the catheter insertion site, or other defects in the peritoneal membrane. We describe 3 patients (who underwent five surgical procedures), illustrating the complexity of the problem.

Indomethacin-induced renal insufficiency: recurrence on rechallenge.

We have reported a case of acute oliguric renal failure with hyperkalemia in a patient with cirrhosis, ascites, and cor pulmonale after indomethacin therapy. Prompt restoration of renal function followed drug withdrawal, while re-exposure to a single dose of indomethacin caused recurrence of acute reversible oliguria. Our case supports the hypothesis that endogenous renal prostaglandins play a role in the maintenance of renal blood flow when circulating plasma volume is diminished.

Autosomal dominant polycystic kidney disease: presentation, complications, and prognosis.

Fifty-three symptomatic adults with autosomal dominant polycystic kidney disease were studied retrospectively for a mean follow-up of 12 years (range 10 months to 33 years). Diagnosis was confirmed by either x-ray, ultrasound, laparotomy, or autopsy. Commonest presenting clinical findings were flank pain (30%), hypertension (21%), symptomatic urinary tract infection (UTI) (19%), gross hematuria (19%), and palpable masses (15%).

The use of streptokinase to treat renal artery thromboembolism.

The effects of streptokinase are difficult to determine. Furthermore, it has toxic side effects, and renal function may not recover from its use. However, because of favorable experiences with this drug in the early treatment of venous thromboembolism and following myocardial infarction, as well as the favorable findings with early perfusion in the dog model, the use of local streptokinase may be justified if the infusion is begun early, preferably within four to six hours.

Rapid progressive glomerulonephritis: relapse after prolonged remission.

Three patients with epithelial cell crescents and rapid progressive glomerulonephritis (RPGN) had prolonged remission, presumably induced by treatment with maintenance oral prednisone and cyclophosphamide plus plasmapheresis. Patient 1 had anti-glomerular basement membrane-mediated RPGN, patient 2 had an immune complex disease, and patient 3 did not show any immune deposits. After a two-year remission in two patients and a greater than one-year remission in the third patient, renal function deteriorated.

Congenital polydactyly and polymetatarsalia: classification, genetics, and surgical correction.

Polydactyly, one of the most common congenital deformities, is inherited and often several members of a family are affected. The condition may range from a small amount of additional soft tissue without osseous structure to a complete, fully developed extra digit or digits. The primary treatment is surgical removal.

Infectious complications with plasmapheresis in rapidly progressive glomerulonephritis.

We recently used plasmapheresis to treat eight patients with rapidly progressive glomerulonephritis. Life-threatening infections developed in five patients, three of which were caused by opportunistic pathogens. In contrast, only two infections occurred in 21 patients with similar renal disease treated with immunosuppressive drugs but not with plasmapheresis.