Immunoassays for quantifying choriogonadotropin compared for assay performance and clinical application.

We examined calibration and accuracy, precision, sensitivity, specificity, and "hook" effects for recently revised automated choriogonadotropin (hCG) immunoassay systems (Baxter-Dade Stratus II, Abbott IMx intact hCG and total beta hCG) and compared them with a widely used immunoradiometric assay (Hybritech). We estimated hCG in pregnant women, women with trophoblastic disease, nonpregnant young and menopausal women, normal men, and men with testicular tumors. We found clinically unimportant differences in calibration (all calibrated to the 3rd International Standard). Detection of hCG by all four assays was limited by their responses in serum from nonpregnant women and men. Precision within-run was best for the automated instruments, but all four assays had similar between-run precision. The Hybritech, Stratus, and IMx intact assays are specific for intact hCG. The IMx total beta assay quantifies both free beta subunit and beta subunit present in intact hCG. There is a clinically important hook effect in the Hybritech assay but not the Stratus or IMx assays (to 1.2 x 10(6) int. units/L). Results for pregnant women were similar by all four assays. We measured "hCG" to 8 int. units/L in menopausal women, which weakly correlated with concentrations of lutropin and follitropin and was, in part, explained by crossreactivity. There was no sample-probe carryover in either instrument. We found the IMx diluting module as well as results at the extremes of the IMx calibration curves (less than 10, 800-1200 int. units/L) unreliable but encountered no such problems with the Stratus system. Both automated systems involve batch analyzers with limited throughput but provide hCG concentration estimates much more quickly than the Hybritech assay can.     

Cerebellar target neurons provide a stop signal for afferent neurite extension in vitro.

The contributions of cell-cell interactions to the establishment of specific patterns of innervation within target brain regions are not known. To provide an experimental analysis of the regulation of afferent axonal growth, we have developed an in vitro assay system, based on the developing mouse cerebellum, in which afferent axons from a brainstem source of mossy fiber afferents, the basilar pontine nuclei, were cocultured with astroglia or granule neurons purified from the cerebellum. In the absence of cells from the cerebellum, pontine explants produced axons that fasciculated and extended rapidly on a culture surface treated with poly-lysine or laminin. When pontine neurites grew onto cerebellar astroglial cells, outgrowth was more abundant than on substrates alone, suggesting that glial cells provide a positive signal for axon extension. Time-lapse video microscopy indicated that the rate of neurite extension increased from less than 50 microns/hr to more than 100 microns/hr when axonal growth cones moved from the culture substratum onto an astroglial-cell surface. Acceleration of neurite extension was also observed as pontine neurites grew onto other pontine neurites. By contrast, when pontine neurites grew on granule neurons, the appropriate targets of mossy fibers, the length of pontine neurites was greatly reduced. As growing axons terminated on granule neurons, the target cells appeared to provide a "stop-growing signal" for axon extension. The length of pontine neurites decreased with increasing granule neuron density. Two lines of evidence suggested that the stop signal was contact mediated. First, video microscopy showed that pontine growth cones stopped extending after contacting a granule neuron. Second, the length of afferent axons was not reduced when pontine neurites grew at a distance from granule neurons. Competition experiments where both astroglia and granule neurons were plated together suggested that the growth arrest signal provided by granule neurons could override the growth-promoting signal provided by astroglial cells. These results suggest that specific cell-cell interactions regulate the growth of pontine afferent axons within their cerebellar target, with axoaxonal and axoglial interactions promoting axon extension and axon-target cell interactions interrupting axon extension.     

Diagnosis of acute myocardial infarction from sequential enzyme measurements obtained within 12 hours of admission to hospital.

A prospective study was made of sequential changes in serum creatine kinase (CK) and CK-MB isoenzyme activity within the 12 hours following admission to the coronary care unit on 65 patients with recent chest pain. CK determinations were performed in the laboratory or in the coronary care unit using a dry reagent strip analyser. Slope values for log CK/hour and log CK-MB/hour were calculated, used to confirm or exclude the diagnosis of myocardial infarction, and compared with diagnosis by conventional means. Compared with retrospective diagnosis using all available information, the CK slope had a sensitivity of 100% and a specificity of 94%. This compared with a sensitivity of 94% and specificity of 90% for diagnosis using upper reference limits alone. Determination of CK slope permits very rapid and accurate biochemical confirmation or exclusion of myocardial infarction and the possibility of performing the measurements on the coronary care unit. It additionally offers the prospect of major cost savings resulting from early discharge or transfer from the coronary care unit.     

Carcinogenic polycyclic aromatic hydrocarbon-DNA adducts and mechanism of action

Polycyclic aromatic hydrocarbons (PAHs) are a class of widespread environmental carcinogens. Most of our knowledge of their mechanisms of metabolic activation to DNA-binding "ultimate carcinogenic" metabolites has come from analysis of the DNA interaction products formed by these highly reactive intermediates. Studies of their role in forming DNA-binding intermediates identical to those formed in vivo from the PAH itself have also allowed identification of the particular cytochrome P450 enzymes involved in activating various structural classes of carcinogenic PAHs. It has been established that PAHs, after metabolic activation in vivo, are capable of inducing mutations in oncogenes and, by inducing multiple mutations, may result in tumors. PAHs also cause changes in cellular gap-junction communication similar to those caused by the tumor promoter 12-O-tetradecanoylphorbol-13-acetate. Thus, PAHs may also act through a promotional mechanism in addition to serving as tumor initiators. Previous studies on these mechanisms are described and summarized.     

Atypical polypoid adenomyoma: a case report with ultrastructural examination

A case of atypical polypoid adenomyoma occurring in a 40 yr-old female is reported. The lesion was composed of irregular glands lined by atypical epithelium lying in a spindle cell stroma containing smooth muscle cells. The mitotic count of the stroma was less than 1 per 10 high power fields. Squamous metaplasia was present in the glandular elements. Ultrastructural examination of the stroma confirmed the presence of smooth muscle cells. The lesion is compared with similar cases previously reported. The differential diagnosis is considered, including endometrial adenocarcinoma, adenomyosis, endometrial polyps and mixed Mullerian tumours. Atypical polypoid adenomyoma is a benign lesion, and conservative management is recommended.     

Potential impact of hormonal male contraception: cross-cultural implications for development of novel preparations

The prospect of a hormonal male contraceptive is no longer distant. Data on the potential impact of this improvement in contraceptive provision, however, is limited, particularly between different cultures. We have therefore carried out a multi-centre study to assess men's attitudes to proposed novel hormonal methods. Questionnaire-based structured interviews were administered to men in Edinburgh, Cape Town, Shanghai and Hong Kong. Approximately 450 men were interviewed in Edinburgh, Shanghai and Hong Kong, and a slightly larger group (n = 493) in Cape Town to give samples (n > 150) of black, coloured and white men. Knowledge of existing male and female methods of contraception was high in all centres and groups. The majority of men welcomed a new hormonal method of contraception, 44-83% stating that they would use a male contraceptive pill. Overall, a pill was more acceptable than an injectable form (most popularly given at 3-6 month intervals); long-acting implants were least so except in Shanghai. Familiarity with comparable female methods appeared to influence acceptability, for both oral and injectable methods. Hong Kong was the only centre where a male method (condom) was currently the most commonly used; men there appeared to rate the convenience of condoms highly while being least likely to think that they provided effective protection against pregnancy compared to other centres, and were least enthusiastic about novel male methods. The acceptability of potential male hormonal methods of contraception was high in some groups but showed wide variability, determining factors including cultural background and current contraceptive usage. These results suggest that the emerging emphasis that men should have greater involvement in family planning will be substantiated when appropriate contraceptive methods become available.     

Semi-automated method for the determination of free fatty acids in plasma

A semi-automated method for the determination of free fatty acids in plasma based on Mosinger's manual method (Mosinger, 1965) is described and the results of a comparison with Dole's titrimetric method (Dole, 1956) are presented. There is almost perfect correlation between the two methods, and the automated technique is simple, reliable, and significantly more accurate and precise than the titrimetric method.     

Fusion of interleukin-2 to subunit antigens increase their antigenicity in vitro due to an interleukin-2 receptor beta-mediated antigen uptake mechanism

Subunit vaccines, based on one or more epitopes, offer advantages over whole vaccines in terms of safety but are less antigenic. We investigated whether fusion of the cytokine interleukin-2 (IL-2) to influenza-derived subunit antigens could increase their antigenicity. The fusion of IL-2 to the subunit antigens increased their antigenicity in vitro. Encapsulation of the subunit antigen in liposomes also increased its antigenicity in vitro, yet encapsulation of the subunit IL-2 fusion did not. The use of anti-IL-2 receptor beta (IL-2Rbeta) antibody to block the receptor subunit on macrophages suggested that the adjuvancy exerted by IL-2 in our in vitro system is due to, at least in part, a previously unreported IL-2Rbeta-mediated antigen uptake mechanism.     

Cardioplegic solution: a contamination crisis

Eleven patients were given varying doses of cardioplegic solution contaminated with Enterobacter cloacae. Five patients died. Early bleeding, necessitating reoperation, occurred in eight patients and a total of 126 units of blood and 203 units of platelets were given (range 2 to 19 and 15 to 47 units, respectively). Mycotic aneurysms developed in four patients, rupturing between the ninth and eleventh postoperative day. Only one of these patients survived. Other complications included adult respiratory distress syndrome (three patients), renal failure (four patients), sternal infections (six patients), and organic brain syndrome (five patients). Although some factors of gram-negative septicemia were identified in retrospect, others were masked by the clinical setting in which it occurred. We recommend that each dose of cardioplegic solution be prepared on an individual basis and used immediately. We also recommend that "sternal blood" be cultured on all patients. The subtle features of "gram-negative septicemia" necessitate urgent investigation and treatment. The combination of low white cell count, high cardiac output, and low peripheral vascular resistance should be assumed to indicate septicemia until proved otherwise. A full coagulation screen including platelet function and fibrin degradation products should be performed in any and all patients with these findings. Mycotic aneurysms mandate urgent reoperation with interposition of a saphenous vein segment of these patients are to survive.     

Fenfluramine treatment in infantile autism. Neurochemical, electrophysiological, and behavioral effects

As part of a multicenter, collaborative project, response to fenfluramine was assessed in 10 autistic outpatients. After 4 months of treatment, blood serotonin concentrations decreased an average of 60 per cent and returned to pretreatment levels after 2 months on placebo. This reduction was accompanied by a decrease in certain behavioral symptoms, including motor activity, distractibility, and mood disturbances. Baseline evoked potential recordings indicated that autistic patients tended to have a larger amplitude of the P3 component to frequent tones as compared to age-matched controls. A tendency toward "normalization" of the P3 effect was observed during the medication trial and during the final placebo period. Treatment response was not related to initial serotonin levels, and no major clinical side effects were associated with fenfluramine.