A phylogenetic study of the structural and functional characteristics of corticosteroid binding globulin in primates

A monospecific antiserum against human corticosteroid binding globulin (hCBG) has been used to identify structural similarities between hCBG and CBG in the blood of other primates and representative species of different vertebrate classes. Double immunodiffusion analysis indicated that only CBG in Old World monkeys and apes cross-react with the hCBG antiserum. This was confirmed by a solid-phase radioimmunoassay for hCBG which also demonstrated that CBG in apes is immunologically identical to hCBG and that Old World monkey CBG comprises most, but not all, of the hCBG epitopes. The electrophoretic mobilities of human, gorilla and gibbon CBG were similar (RF 0.50-0.51), but differed from Old World monkey CBG (RF 0.44-0.49) and chimpanzee CBG (RF 0.47). Although serum/plasma cortisol binding capacities were similar in Old World primates, the dissociation half-times (t 1/2) of cortisol were higher from human and ape CBG (18-25 min) than from Old World monkey CBG (14-18 min). The steroid binding specificities of human and ape (CBG corticosterone greater than cortisol greater than progesterone greater than or equal to testosterone) were also different from those of Old World monkey CBG (corticosterone much greater than cortisol approximately equal to progesterone greater than testosterone). Lemur plasma cortisol binding capacity and CBG dissociation t 1/2 of cortisol were similar to hCBG, but its steroid binding specificity was different (cortisol greater than corticosterone greater than progesterone greater than or equal to testosterone) and it did not cross-react with the hCBG antiserum.(ABSTRACT TRUNCATED AT 250 WORDS)

Multicenter collaborative evaluation of a standardized serum bactericidal test as a prognostic indicator in infective endocarditis

One hundred twenty-nine patients with bacterial endocarditis were evaluated in a multicenter collaborative study to determine whether a standardized serum bactericidal test could predict the outcome of the infection. All centers used a microdilution test method that defined all known test variables, including inoculum size, culture medium, dilution technique, incubation time, method of subculture, and bactericidal endpoint. Peak serum bactericidal titers of 1:64 or more and trough serum bactericidal titers of 1:32 or more predicted bacteriologic cure in all patients. The traditionally recommended serum bactericidal titer of 1:8 had statistically significant predictive accuracy at trough antibiotic levels only. The serum bactericidal test was a poor predictor of bacteriologic failure and ultimate clinical outcome, which depends on many factors. Wider recognition by physicians and clinical microbiologists that this in vitro test of antimicrobial activity can accurately predict bacteriologic success but cannot accurately predict either bacteriologic failure or clinical outcome could lead to a better consensus about its appropriate use. On the basis of the results of this study, peak serum bactericidal titers of 1:64 or more and trough serum bactericidal titers of 1:32 or more are recommended to provide optimal medical therapy for infective endocarditis.

Identification and characterization of a human corticosteroid binding globulin variant with a reduced affinity for cortisol

A corticosteroid binding globulin variant (CBGv) has been identified in a serum sample taken from an apparently healthy woman during late pregnancy. Identification was based on the observation that it exhibited approximately half the cortisol binding capacity expected when compared to its concentration measured by radioimmunoassay (RIA). Affinity purification of CBGv excluded the possibility that this anomaly was caused by assay interference, and demonstrated that immunoreactive CBGv was capable of binding cortisol. The CBGv had a molecular weight (63 800) similar to normal CBG, and no evidence of molecular aggregation was found by gel filtration. Although the electrophoretic mobility, isoelectric profile and immunochemical identity of CBGv appeared to be similar to normal CBG, it focussed as two distinct bands (pI 5.48 and pI 5.53) after desialylation with neuraminidase, unlike normal CBG which focuses only at pI 5.48. Investigation of the steroid binding characteristics of CBGv revealed a reduced association-rate constant (Ka = 1.05 X 10(9) l/mol) and dissociation half-time (12.5 min) when compared with normal CBG (Ka = 1.39 X 10(9) l/mol and 25 min at 0 degree C) but an apparently normal steroid binding specificity. Although the physiological significance of this variant is not known, the cortisol concentration in the variant serum was within the normal range of women during late pregnancy. No other CBG variants were identified among other normal controls (n = 66) or nine patients with Cushing's syndrome. It is suggested that comparisons between cortisol binding capacity and RIA will reveal other variants of CBG, and lead to greater understanding of their physiological significance.

Serum steroid binding protein concentrations, distribution of progestogens, and bioavailability of testosterone during treatment with contraceptives containing desogestrel or levonorgestrel

The oral administration of 150 micrograms desogestrel and 30 micrograms ethinyl estradiol (EE2) increases (P less than 0.001) serum concentrations of sex-hormone-binding globulin (SHBG) and corticosteroid-binding globulin (CBG), whereas treatment with 150 micrograms levonorgestrel and 30 micrograms EE2 only increases serum CBG concentrations. No changes in serum albumin concentrations occurred during or after treatment with either preparation, and increases in SHBG and CBG returned to the pretreatment values 1 month after treatment ceased. The serum distribution of levonorgestrel was unchanged during treatment, whereas the increase in serum SHBG concentrations after treatment with the preparation containing desogestrel decreased (P less than 0.001) the percentage of non-protein-bound 3-keto- desogestrel and the percentage of albumin-bound 3-keto- desogestrel but increased (P less than 0.001) the SHBG-bound fraction. Oral contraceptives containing either progestogen decrease the mean serum non-protein-bound testosterone concentrations, especially during treatment with desogestrel (P less than 0.001), and desogestrel may therefore by the more appropriate progestogen for the treatment of women prone to androgenic side effects.

Multi-element analysis of the obese subject by in vivo neutron activation analysis

The Leeds facility for in vivo neutron activation analysis has been modified and calibrated for the simultaneous measurement of nitrogen, potassium, sodium, chlorine, phosphorus and calcium in obese patients weighing up to 210 kg. The effects of body size and shape were incorporated into the calibration by measuring 14 anthropomorphic phantoms of known composition representing individual patients being treated for obesity. The phantoms were constructed from tissue substitutes representing lean, skeletal and adipose tissues, arranged to simulate the distributions of the corresponding tissues within the patients, as visualised by CT scanning. The precision of the method, determined by measuring a single phantom ten times over a period of ten weeks, is between two and three per cent for all elements except calcium, for which it is 11.3%. Accuracy is estimated to be similar to precision. The procedure has been used to study changes in body composition of patients undergoing therapeutic starvation.

Characterization of a monoclonal antibody to human sex hormone binding globulin

We have produced a monoclonal hybridoma cell line ( S1B5 ) that secretes an IgG2 alpha immunoglobulin with a high affinity (Kd 0.38 X 10(-11) M) for 125I-labelled sex hormone binding globulin (SHBG), and which will specifically immunoprecipitate SHBG from serum. The antibody is produced in high titre in culture medium and ascites fluid, and can be purified to apparent homogeneity by protein A affinity chromatography. When examined by isoelectrofocusing , a characteristic series of bands, which bind 125I-SHBG, are observed at pH 8.5-9. Competitive, superimposable, displacement of 125I-SHBG from the antibody is achieved with dilutions of human, chimpanzee and gorilla sera at comparable SHBG concentrations. Partial cross-reaction is observed with sera from other Old World primates, but not with sera from New World monkeys or any other vertebrate species studied.

Respiratory illness in conference participants following exposure to rug shampoo

Persons participating in a conference in a major city motel experienced transient mild respiratory illness associated with their presence in the motel conference rooms. The illness was characterized by coughing, sneezing, sore throat, headache, eye irritation, and other symptoms of exposure to a respiratory irritant. Investigation incriminated a chemical shampoo used to clean the conference room rugs approximately one week earlier. Repeated cleaning of the rugs to remove excess cleaning compound eliminated the problem. Excessive application of the shampoo, coupled with a poorly ventilated environment, apparently produced a chemical concentration sufficient to cause clinical illness.

Group III atypical mycobacterial infections

We retrospectively and prospectively examined the clinical presentation, course of disease, and response to therapy in 63 patients whose mycobacterial isolates were identified as Runyon group III atypical mycobacteria. All of the patients except four had pulmonary disease similar to typical pulmonary tuberculosis. The others had scrofula or abxcess. There was a male predominance and whites were slightly more frequently infected in our series. Forty-six percent of the patients were from rural Oklahoma. Skin testing and chest roentgenography were important, but culture of the organism appeared to be the only productive method of distinguishing the atypical disease from typical tuberculosis. Eighty-one percent had an associated disease. The isolates showed a very high rate of primary drug resistance, and this was reflected in the difficulty in controlling the infection.