Antigenic properties of ovalbumin following heat denaturation at different temperatures: Comparison with enzymatic Denaturation

Eighteen monoclonal antibodies (MAbs) raised from mice which were immunized with either native ovalbumin (NOA) or ovalbumin which had been heat denatured at 100°C, (HDOA) were used to study antigenic modifications induced by either heat or subtilisin treatment. Using enzyme immunoassays (EIA) we have defined three major groups of antigenic sites: Group I thermolabile native epitopes; Group II relatively thermostable native epitopes; Group III epitopes specific to heat‐denatured ovalbumin. Heatdenatured ovalbumin can be separated into monomers and polymers which constitute 1% and 99% of the molecules respectively. Whereas MAbs belonging to Groups I and II bound to the monomeric form (mHDOA), MAbs belonging to Group III only bound to the polymeric form (pHDOA). Plakalbumin (PK) behaved similarly to pHDOA since it was recognized by many MAbs from Group III and a few from Group II. Nevertheless, PK remained as a monomeric molecule, whereas heat‐denatured ovalbumin existed mainly as polymeric aggregates. The epitopes present on ovalbumin after different heating procedures (time/temperature) were found to be stable after cooling, thus allowing specific recognition by different MAbs. The critical modification of the protein structure was found to take place at 75°C. Two main conclusions can be drawn from these results: (i) heat and enzymatic denaturation of ovalbumin led to similar antigenic modifications—these may be explained by the exposure of hydrophobic residues in both HDOA and PK as evidenced from 8‐anilino‐1‐sulphonic acid fluorescence spectra; (ii) the panel of ovalbumin‐specific MAbs was able to differentiate between the various heat treatments which had been applied to ovalbumin within the range 65–85°C, even after subsequent cooling. The aggregation of ovalbumin molecules during the heating process constitutes the main type of antigenic modification.     

Assessment of bioequivalence after subcutaneous and intramuscular administration of urinary gonadotrophins

The objective was to demonstrate bioequivalence between s.c. and i.m. administration of Humegon (FSH/LH ratio 1:1) and Normegon (FSH/LH ratio 3:1). In two randomized, single-centre, cross-over studies, 18 healthy volunteers on each formulation were assigned to one of the two administration sequences. Subjects were given single doses of one of the above gonadotrophins after endogenous gonadotrophin production had first been suppressed using high-dose oral contraceptive. Subsequently, rate (Cmax, tmax) and extent (AUC) of absorption of follicle stimulating hormone (FSH) and luteinizing hormone (LH) were determined for 14 days. For Cmax and AUC, analysis of variance (ANOVA) was performed on log-transformed data and for tmax ANOVA was performed on ranks. Intramuscular and s.c. injections of Humegon were bioequivalent with respect to the main pharmacokinetic parameters, being AUC and Cmax of FSH absorption. Intramuscular and s.c. injections of Normegon were bioequivalent with respect to the AUC of FSH and not bioequivalent with respect to the Cmax of FSH. For tmax of FSH as well as for most LH variables of both preparations, bioequivalence could not be proven due to the high intra- and interindividual variability and/or concentrations being close to the detection limit. Thus, the main pharmacokinetic FSH variables after i.m. and s.c. administration of Humegon and Normegon were bioequivalent.      

Biological resurfacing of the knee: a review of surgical management

Lesions of the articular surfaces of the knee have been managed by various techniques over the last 50 years. Surgical management has involved: excising the damaged area, refashioning the underlying bone to produce a fibrous response, and introducing allograft, autograft and synthetic materials to encourage a repair matrix. The techniques and their pitfalls are reviewed and discussed, and suggestions made as to the direction of future studies for the repair of osteochondral lesions in the painful knee.     

Hypospadias trends in two US surveillance systems

OBJECTIVE: Hypospadias is a common congenital anomaly, the cause of which is unknown. Unexplained increases in the rates of hypospadias occurred in five European countries in the 1970s and 1980s. We examined data from two birth defects surveillance systems in the United States for evidence of similar trends. METHODOLOGY: The Metropolitan Atlanta Congenital Defects Program (MACDP) provided birth prevalence rates from 1968 to 1993. The nationwide Birth Defects Monitoring Program (BDMP) provided rates from 1970 to 1993. MACDP data are population-based and could be categorized by the severity of the hypospadias. BDMP data allowed analysis of rate trends for the four census regions of the United States. RESULTS: Data from both surveillance systems showed an approximate doubling of hypospadias rates in the 1970s and 1980s. MACDP data showed that the rate of severe cases increased while the ratio of mild to severe cases decreased. BDMP data showed that hypospadias rates increased markedly in all four regions of the United States. CONCLUSIONS: The observed increases are unlikely to be attributable to increased sensitivity of the surveillance systems or the identification of more mild cases by physicians over time, because either trend would have increased rather than decreased the ratio of mild to severe cases. If real, these trends represent the largest number of cases and the first report of an increase in hypospadias rates outside of Europe. Additional investigation of a possible increase in hypospadias rates is warranted.