On-line detection of nonspecific protein adsorption at artificial surfaces.

A detailed understanding of the interaction of proteins with artificial surfaces is essential for many applications in medicine and biochemistry. The affinity of surfaces toward proteins may, for instance, remove pharmacological proteins from media or control the adherence of pathogenic bacteria to protheses. Only a few analytical techniques now exist that can be used to study the binding process in real time, using unlabeled proteins. By investigating the adsorption kinetics of fibrinogen at differently terminated self-assembled monolayers (SAMs) of alkanethiols on thin gold films, it is demonstrated that acoustic plate-mode sensors are a promising analytical tool for studying the adsorption of proteins. In agreement with previous studies for fibrinogen, it is shown in situ that hexa(ethylene glycol)-terminated SAMs (HS(CH2)11 (OCH2CH2)6OH) exhibit very low protein adsorption and that methyl-terminated SAMs (HS(CH2)11CH3) tend to absorb large amounts of protein nonspecifically. The observed adsorption kinetics deviate from classical Langmuir behavior; these kinetics are compatible with a mechanism that involves an unfolding of fibrinogen after adsorption. Film quality is controlled by IR, XPS, and contact angle measurements.

Parenteral essential amino acids in acute renal failure.

Parenteral 1.75 per cent L-essential amino acids in 47 per cent dextrose (Group I 11 patients) or 47 per cent dextrose (Group II, 9 patients) were administered to patients with severe acute renal failure in a single blind-controlled study. Survival rates (55 per cent in Group I and 56 per cent in Group II) and duration of renal failure were similar in the two groups. Rate of daily rise in blood urea nitrogen was significantly reduced during intravenous nutrition in Group I but not in Group II. Serious complications of intravenous nutrition did not occur. Since improved nitrogen metabolism is demonstrated, further trials of essential amino acid therapy in acute renal failure are indicated.

Normal serum-lipids in renal-transplant patients.

In contrast to previous reports, most patients (78%) with a successful renal transplant being followed up at the University of Kentucky Medical Center had a normal serum-lipid profile. The patients with hyperlipidaema (22%) had normal fasting insulin levels; they received similar immunosuppressive therapy but were significantly older and more obese than those with normal lipids. This lower prevalence of hyperlipidaemia and the absence of fasting hyperinsulinaemia are tentatively attributed to the use of alternate-day corticosteroid therapy in stable renal-transplant patients. If confirmed, the relative infrequency of hyperlipidaemia in patients of alternate-day corticosteroid therapy would be an additional advantage of that therapy over a daily regimen.

Minimising the risks of treating acute allograft rejection.

The risks of treating allograft rejection are primarily related to high-dose steroid therapy. To determine when the possible benefit of anti-rejection therapy might not justify the risks, we analysed 20 severe rejection (SAR) episodes for indices of reversibility. Prior renal function was similar in all patients. Ccr fell to 10 ml/min or less, but degree of renal dysfunction was not predictive of reversibility, nor were time since transplant, oliguro/anuria, proteinuria, or hypertension. The only consistent finding was that function began to improve in reversible rejection 3.8 +/- 1 days after beginning therapy. Our rejection treatment, based on this finding, is to use gram doses of IV prednisolone, up to three times in five to seven days. Among 41 patients with 45 grafts so treated, there was no fatality or gastrointestinal haemorrhage. Other complications (fistulae and/or infections) were related to total dose and frequency, to intensive therapy during severe renal dysfunction or to urinary leaks. Limitation of the period of high-dose steroid therapy was associated with reduced morbidity and mortality in renal allograft recipients.