Determination Of Human Chorionic Gonadotropin Research Articles

A fluorescent immunochromatographic strip based on CsPbBr3/CsPb2Br5@SiO2 facile encapsulation in pure water for the detection of human chorionic gonadotropin (HCG) antigen

Fluorescent immunochromatographic test (FICT) strips have received extensive attention due to their virtue of simple operation, low cost, and a point-of-care (POC) assay. In recent years, people are constantly seeking new labels to improve the sensitivity of immunosensors. Perovskite nanocrystals (PNCs) possess strong fluorescence and a narrow emission peak, making them an excellent choice as a new fluorescent signal label. Herein, we have developed a simple, fast, and environmentally friendly method to synthesize CsPbBr3/CsPb2Br5@SiO2 with the good water stability and high biocompatibility. These CsPbBr3/CsPb2Br5@SiO2 have been applied to construct FICT strips. To achieve the quantitative determination of human chorionic gonadotropin (HCG), a lab-made FICT strips detection system was established. The FICT strips had a good linear relationship to HCG in the range of 5–500 ng/mL, and the detection limit was 2.09 ng/mL. In addition, the recovery results of HCG detection in human urine samples also proved the feasibility of this FICT strips. CsPbBr3/CsPb2Br5@SiO2 can also be modified with different biomarkers for functionalization, which exhibits a promising application in the development of sensing platform of FICT strips.

Development of radioimmunoassay system for determination of human chorionic gonadotropin in human sera

The main objective of this study was the preparation and evaluation of the primary reagents for the liquid phase human chorionic gonadotropin-radioimmunoassay (HCG-RIA) kit. Polyclonal antibody is specific and valid; monoclonal antibodies are more specific. In HCG-RIA technique, polyclonal antibodies for βHCG subunits with high binding and displacement % were used. 125I-HCG radioactive tracer was prepared with high yield 71.58 ± 0.92%, purity 99.2 ± 0.05%, and specific activity 170.42 ± 1.65 µCi/µg using chloramine T method, βHCG polyclonal antisera and HCG standards in assay buffer matrix were locally prepared. In-house HCG-RIA was developed with high sensitivity 0.5 mIU/ml, specificity (99%), precision (CV% < 6.4 and < 8.3 for intra-and inter-assay, respectively), and accuracy (recovery range 96.4–104.3%) could be used for quantitative estimation of HCG in human sera for monitoring pregnancy and diagnosis of gestational trophoblastic diseases.

Simple and Sensitive Electrochemical Sandwich-type Immunosensing of Human Chorionic Gonadotropin based on b-cyclodextrin Functionalized Graphene

The effective detection of human chorionic gonadotropin (HCG) is considerably important for the clinical diagnosis of both of early pregnancy and nonpregnancy-related diseases. In this work, a simple and sensitive electrochemical sandwich-type immunosensing platform was designed by synthesizing b-cyclodextrin (CD) functionalized graphene (CD/GN) hybrid as simultaneously sensing platform and signal transducer coupled with rhodamine b (RhB) as probe. In brief, GN offers large surface area and high conductivity, while CD exhibits superior host-guest recognition capability, thus the primary antibody (Ab1) of HCG can be bound into the cavities of CD/GN to form stable Ab1/CD/GN inclusion complex; meanwhile, the secondary antibody (Ab2) and RhB can also enter into the cavities, producing RhB/Ab2/CD/GN complex. Then, by using Ab1/ CD/GN as sensing platform and RhB/Ab2/CD/GN as signal transducer (in which RhB was signal probe), a simple sandwich-type immunosensor was constructed. Under the optimum parameters, the designed immunosensor exhibited a considerable low analytical detection of 1.0 pg mL&lt;sup&gt;−1&lt;/sup&gt; and a wide linearity of 0.002 to 10.0 ng mL&lt;sup&gt;−1&lt;/sup&gt; for HCG, revealing the developed sandwich-type electrochemical immunosensing platform offered potential real applications for the determination of HCG.

Cerebrospinal Fluid Levels of AFP and hCG: Validation of the Analytical Method and Application in the Diagnosis of Central Nervous System Germ Cell Tumors.

The determination of Human Chorionic Gonadotropin (hCG) and Alpha Fetoprotein (AFP) levels on serum and amniotic fluid plays a fundamental role in the diagnosis and follow-up of specific physiological or pathological conditions (e.g., pregnancy, threat of abortion or germ cell tumors). Recently, the quantification of hCG and AFP in other biological fluids has gained great attention to support the diagnosis, prognosis and follow-up of neoplastic diseases deriving from trophoblastic cells, such as germinomas. Most of the commercial kits for hCG and AFP assays are developed to be used on biological fluids such as serum/plasma and/or urine by manufacturing companies. The aim of this work was to evaluate the suitability of the analytical method certified for the use on serum, and/or amniotic fluid for the quantification of hCG and AFP in cerebrospinal fluid, carrying out an internal validation protocol. The data reported here show that the automated immunochemical method is fit for quantification of hCG and AFP in cerebrospinal fluid (CSF), allowing selective and specific diagnosis of secreting germ cell tumors. This is confirmed by the positive correlation between elevated levels of hCG or AFP and the diagnosis of brain tumors.

A capillary driven microfluidic chip for SERS based hCG detection

In this study, a capillary driven microfluidic chip-based immunoassay was developed for the determination of Human Chorionic Gonadotropin (hCG) protein, which is prohibited by the World Anti-Doping Agency (WADA). Here, we used antibody modified magnetic metal organic framework nanoparticles (MMOFs) as a capture prob in urine sample. MMOF captured hCG was transferred in a capillary driven microfluidic chip consisting of four chambers, and the interaction of MMOF with gold nanorods labelled with 5,5′-Dithiobis-(2-nitrobenzoic acid) (DTNB) as a Raman label was carried out in the capillary driven microfluidic chip. The movement of MMOF through first chamber to the last chamber was achieved with a simple magnet. In the last chamber of capillary driven microfluidic chip, SERS signals of DTNB molecules from the sandwich complex were recorded using a Raman spectrophotometer. The selectivity of the developed method was demonstrated by applying the same procedure for the detection of Human Luteinizing Hormone (hLH), Human Chorionic Gonadotropin Hormone (hGH) and Immunoglobulin G (IgG) protein. The regression coefficient and limit of detection obtained from the standard addition method were found as 0,9985 and 0,61 IU/L, respectively. Furthermore, the conventional ELISA method confirmed that the results obtained by the presented method were acceptable with the similarity of 97.9% in terms of average recovery value, for the detection of hCG in urine samples. The analysis system developed for target proteins will be an alternative technique such as Western Blot used in routine analysis that is expensive and time consuming.

An enzyme immunoassay to determine human chorionic gonadotropin (HCG) in serum and urine samples using an ultra-microanalytical system

The determination of Human Chorionic Gonadotropin (HCG) in biological fluids is of great interest in the early pregnancy diagnostics, the evaluation of pregnancy disorders, as a tumor marker, as a screening procedure for anti-doping control, and many other purposes. A simple sandwich-type UltraMicro Enzyme-Linked ImmunoSorbent Assay (UMELISA) has been developed for the measurement of HCG in serum and urine samples. Strips coated with a high affinity MAb directed against HCG are used as solid phase, to ensure the specificity of the assay. The HCG assay was completed in 1.5 h, with a measuring range of 0.76–400 mIU/mL. The intra- and inter-assay coefficients of variation were lower than 10 %, depending on the HCG concentrations evaluated. Recovery percentages were 96.43–97.16 % (serum) and 98.10–99.04 % (urine). The assay detected intact HCG, nicked HCG, HCG β, and nicked HCG β, and did not recognize any of the interfering molecules tested. Regression analysis showed a good correlation with Elecsys in serum (n = 1459, r = 0.952, ρc = 0.948) and urine (n = 869, r = 0.988, ρc = 0.978). A good correlation was also found with 84 RIQAS samples analyzed with the kits Elecsys (r = 0.969, ρc = 0.957), Architect (r = 0.982, ρc = 0.970), Dimension (r = 0.989, ρc = 0.977), and Bioscience (r = 0.992, ρc = 0.980), all with a p < 0.01. Comparison with transvaginal ultrasonography in early pregnancy detection showed a specificity and a sensitivity of 100 % (n = 2385, κ = 1). The analytical performance characteristics of UMELISA HCG endorse its use for the quantification of HCG in serum and urine samples. This assay will make a cost-effective diagnostic kit accessible to low-income countries and is now available in the Cuban Public Health System.

Fabrication of Miniaturized Microfluidic Paper-Based Analytical Devices for Sandwich Enzyme-Linked Immunosorbent Assays using INKJET Printing

Main application of microfluidic paper-based analytical devices (µPADs) is for low-cost and portable assays. In order to reduce the cost, miniaturization seems to be an effective way to save reagents, samples, materials, etc. Present study demonstrates that mini-µPADs based on nitrocellulose membrane with only 2 main channels can perform sandwich enzyme-linked immunosorbent assays (ELISA) for quantitative determination of human chorionic gonadotropin (hCG). Moreover, the width and the length of these devices are only about 4.0 and 33.4 mm, respectively. Inkjet printing technology, having the advantages of simple and material-saving process, was used to create hydrophobic barrier. Colorimetric signals from ELISA captured by digital camera and measured by ImageJ software shows that these µPADs can quantitative determine of hCG in the range from 5 to 10 000 ng/mL. Furthermore, duration for each tests is only about 5 min. The success in fabricating miniaturized µPADs shows the potentials to reduce the size of µPADs as well as the amount of needed samples, time and reagents. For all these reasons, this miniaturization concept can be applied to many further applications of analytical biochemical assays.

Electrospun nitrocellulose membrane for immunochromatographic test strip with high sensitivity.

The main goal of this work is to develop an economical, portable, disposable, and reliable point of care paper biosensor based on visualization, which can be used to detect viruses, bacteria, and proteins. However, the sensitivity of immunochromatography test (ICT) strips based on nitrocellulose to target detection has always been a problem. Here, we use anelectrospun nitrocellulose (ENC) fiber membrane instead of traditional nitrocellulose fiber membrane to construct ICT strips for early pregnancy detection. By proper selection of the diameter of theENC fiber to adjust the pore size, porosity, and morphology of the membrane, ICT strips with low flow rate and high protein loading were obtained. Based on these properties, a convenient and sensitive method for the colorimetric determination of human chorionic gonadotropin was developed. Under the optimal conditions, the detection limit of ICT based on ENC membrane is 10mIUmL-1 (S/N = 3), the linear detection range is 5-1000mIUmL-1, and the linear relationship is Y = 0.0434 X - 0.0136 (R2 = 0.9802). In addition, the test striphas good specificity and stability, and will not produce false-positive results. Graphical abstract.

Persistent omental trophoblastic implantation following salpingostomy, salpingectomy and methotrexate for ectopic pregnancy: A case report

2% of all pregnancies are ectopic. Optimal surgical management is currently salpingectomy over salpingostomy, secondary to the risks of persistent trophoblastic tissue or omental implants (15%). However, rare cases of omental trophoblastic implants following laparoscopic salpingectomy have been noted in the literature. Current practice dictates that serial determinations of human chorionic gonadotropin (beta-hCG) levels after salpingectomy are not required, as it is considered a definitive treatment. However, given that these cases are hard to interpret through ultrasound and are almost always detected via sudden-onset abdominal pain and acute haemoperitoneum (33%), an argument can be made for post-operative beta-hCG assessment.

Digital microfluidic platform for automated detection of human chorionic gonadotropin

Determinations of Human chorionic gonadotropin (HCG) are important for diagnosis and monitoring of pregnancy, pregnancy-related diseases and several types of cancers. As a step toward decentralized diagnostic systems, we introduce a format of particle-based immunoassays relying on digital microfluidics (DMF) and magnetic forces to separate and resuspend HCG antibody-coated paramagnetic particles. On this basis, we developed DMF diagnostic platform for automated HCG detection and realized droplet operations at 20 Hz. Using this platform, 10–50 µg/mL of HCG was detected by chemiluminescence method and the linear relationship between HCG concentrations and chemiluminescence signals was obtained. To solve the biofouling problem, we use pluronic additives in reagent droplets. The effect of different additive concentrations on droplet actuation was tested. The DMF immunoassays only take 20 min to finish the whole sample detection process. We propose that the new technique has great potential for eventual use in a fast, low-waste, and inexpensive instrument for the quantitative analysis of proteins and small molecules in low sample volumes.

Effect of different-sized gold nanoflowers on the detection performance of immunochromatographic assay for human chorionic gonadotropin detection

Traditional colloidal gold based immunochromatographic assays (ICAs) that use 20–40 nm gold nanospheres (AuNSs) as signal reporters have low sensitivity given the insufficient brightness of AuNSs. Gold nanoflowers (AuNFs) possess high optical brightness and strong target binding affinity because of their multibranched structures and large specific surface areas. Thus, ICAs with AuNF reporters have better sensitivity than ICAs with conventional AuNSs reporters. In addition, large AuNFs exhibit higher optical absorbance than small AuNFs. To elucidate the effect of AuNF size on the sensitivity of sandwich ICA, AuNFs with five different sizes of 33, 47, 79, 152, and 195 nm were synthesized and used as reporters in ICA strips for pregnancy diagnosis based on the detection of human chorionic gonadotropin (HCG). Medium-sized AuNFs with diameters of 47–79 nm showed the highest sensitivity of 9 mIU/mL. When used to test actual HCG-spiked urine samples, the 47 nm AuNF-based ICA showed two independent linear correlations in low (9 mIU/mL ~ 288 mIU/mL) and high (288 mIU/mL ~ 2304 mIU/mL) HCG concentrations for HCG quantitative detection. The intra- and interassay recovery rates for HCG spiked urine samples ranged from 81.19% to 114.44% with the coefficient of variation (CV) from 3.29% to 8.08%. These results collectively indicate that the AuNF-based ICA has high accuracy. In addition, the proposed AuNF-based ICA method exhibited excellent selectivity for HCG determination. In summary, medium-sized AuNFs can serve as optimal ICA labels in the high-sensitivity detection of disease-related protein biomarkers.

Sandwich-format ECL immunosensor based on Au star@BSA-Luminol nanocomposites for determination of human chorionic gonadotropin

A sandwich-configuration electrochemiluminescence (ECL) immunosensor based on Au star@BSA-Luminol nanocomposites for ultrasensitive determination of human chorionic gonadotropin (HCG) has been developed. In this work, nanostructured Polyaniline hydrogels (Pani) decorated with Pt nanoparticles (Pani/Pt) were utilized to construct the base of this immunosensor, greatly increasing the amount of loaded capture antibodies (Ab1) via linkage reagent glutaraldehyde (GA). The used conducting Pani/Pt nanocomposites possessed the unique features, such as large surface area, high electron transfer speed and favorable electrocatalytic activities of hydrogen peroxide, which offered a prominent platform for this sandwich-sensor and acted as efficient ECL signal amplifier also. Furthermore, we employed horseradish peroxidase (HRP) to block the nonspecific binding sites instead of commonly used bovine serum albumin (BSA), which further amplified the signal of luminol in the present of hydrogen peroxide (H2O2). In addition, Au star@BSA nanocomposites with excellent water solubility, low-toxicity and great biocompatibility were prepared and used to immobilize HCG detection antibodies (Ab2) and luminescent material luminol. Then, the above-synthetized Luminol-Au star@BSA-Ab2 complex was attached to the modified sensor by sandwiched immunoreactions. Under the optimized conditions, the proposed immunosensor exhibited a sensitive detection of HCG in a wide linear range from 0.001 to 500mIUmL−1 with a detection limit of 0.0003mIU/mL (S/N = 3). All the results indicated that such a sandwiched HCG immunosensor exhibited favorable ECL analytical performance. This developed method may be potentially used to recognize other clinical protein and display a novel ideal to construct an immunosensor.

Qualitative Determination of Human Chorionic Gonadotropin in Vaginal Washings for the Early Diagnosis of Premature Rupture of Fetal Membranes.

Purpose This study aimed to evaluate and validate the qualitative human chorionic gonadotropin β subunit (β-hCG) test of the vaginal fluid washings of pregnant women with premature rupture of fetal membranes (PROM). Methods Cross-sectional study of pregnant women between gestational weeks 24 and 39 who underwent consultations in one of our institutions. They were divided into two groups: group A (pregnant women clinically diagnosed with PROM) and group B (pregnant women without loss of amniotic liquid). The patients were subjected to a vaginal fluid washing with 3 mL of saline solution, which was aspirated subsequently with the same syringe. The solution was immediately sent to the laboratory to perform the vaginal β-hCG test with cut-off points of 10 mIU/mL (β-hCG-10) and/or 25 mIU/mL (β-hCG-25). Results The β-hCG-10 test of the vaginal secretion was performed in 128 cases. The chi-squared test with Yates' correction showed a statistically significant difference between the 2 groups (p = 0.0225). The sensibility, specificity, positive predictive value (PPV), negative predictive value (NPV), and accuracy parameters were 77.1%, 43.6%, 52.3%; 70.4%; and 58.6% respectively. The β-hCG-25 test of the vaginal washing was performed in 49 cases. The analysis by Fisher's exact test showed a statistically significant difference between the groups (p = 0.0175). The sensibility, specificity, PPV, NPV, and accuracy parameters were 44.4%, 87.1%, 66.6%; 72.9%; and 71.4% respectively. Conclusions The β-hCG-25 test showed better accuracy for the diagnosis of PROM, and can corroborate the early diagnosis of PROM because it is a simple and quick exam.

Cesarean Scar Ectopic Incidence and Management in a Community Hospital Setting: Case Series [9H

INTRODUCTION: The rate of Cesarean Deliveries has increased from 20.6% in 1996 to 32.9% in 2009. The incidence of scar ectopic pregnancies has increased reaching an estimated incidence of 1:2226. Objective is to identify the incidence and management of cesarean scar ectopic (CSE) pregnancies in a Community Hospital setting in NY State. METHODS: A retrospective chart review from January 2013 to December 2015 was performed. CSE diagnosed with transvaginal ultrasound. Methotrexate (MTX) single or multi-dose regimen was used. Serial serum human chorionic gonadotropin determinations (bhCG) were obtained until a negative result (&lt; 5 mIU/ml). Descriptive data was analyzed using percentages, means and standard deviations. RESULTS: Five cases of CSE were diagnosed in a 3-year period. Women’s mean age was 34.2 ± 5.6 years. The average gestational age at diagnosis was 56 ± 12.9 days, and number of previous cesarean section was 2 ± 0.7. The mean bhCG at diagnosis was 22,540.2 ± 26,436.9 mIU/ml. Only 1 patient required hysterectomy after MTX due to unfavorable decline on bhCG. The mean duration to reach a negative pregnancy test was 36.7 ± 28.4 days. CONCLUSION: We estimate an incidence of 1 of 36 cases of all ectopic pregnancies diagnosed in the last 3 years and the main treatment used is MTX. Speculation is that this rise may be due to an increase in cesarean deliveries in the recent years and to the type of closure technique performed. Further investigation is encouraged to determine the underlying cause and safest management.

Maternal Serum Triple Screening Test and Pregnancy Outcome in Elderly Sudanese Pregnant Ladies in Khartoum State-Sudan

The possibility to deliver infants with congenital defects or diseases is thought to be associated with increased in maternal age. This fact is well established and documented in previous studies done in the United States of America. Infants with birth defects is not the only disastrous outcome, pregnancy and delivery complications, abortion, stillbirth are also known consequences. The aim of this study, to detect a possible association between increased maternal age, and Triple Screening Test results. And compare the findings of the Triple Screening Test results with abnormal pregnancy outcome among Sudanese pregnant ladies. Study performed in ninety-one pregnant ladies accepted to participate. Participants were assigned to two groups; study group including 69 (75.8%) women equal to and above 35 years and control group including 22 (24.2%) women less than 30 years. Structured questionnaire, clinical examinations including ultra-sound for the determination of gestational age were also performed. Blood samples were collected from all participants during the 14th to 20th week of gestational age. Sera were separated and used for the determination of human chorionic gonadotropin, alpha fetoprotein, and free estriol concentrations using standardized quantitative methods (ELISA) collectively known as the Triple Screening Test. In the study group, participants delivered 57 (82.6%) normal healthy infants. Twelve ladies (17.4%) delivered infants with adverse dimorphic features. The defects varied; four (5.8%) had stillbirth, four (5.8%) had abortion at the second trimester, three (4.3%) had premature delivery, and one (1.4%) had intrauterine death. And matching control group, none of the participants (0%) give birth to an infant with congenital defect. Highly significant positive correlation was detected between increase in maternal age and abnormal pregnancy outcome. The Triple Screening Test against the pregnancy outcome in study group, showed statistically significant differences between levels of β-HCG, AFP, and Free estriol and pregnancy outcomes with P-values of 0.000, 0.5240, and 0.000 were obtained using Pearson Chi-squire test of significance, respectively. Study conclude that abnormal pregnancy outcome is strongly associated with increase in maternal age. Also there were strongly association between the Triple Screening Test and abnormal pregnancy outcome.

Peptide aptamer-based biosensor for the detection of human chorionic gonadotropin by converting silver nanoparticles-based colorimetric assay into sensitive electrochemical analysis

We presented an antibody-free electrochemical technique for the determination of human chorionic gonadotropin (hCG) using silver nanoparticles (AgNPs) as the redox reporters and a hCG-specific binding peptide as the receptor. Peptide-induced AgNPs assembly was achieved on the electrode surface that was modified with the same sequence of peptide (recognition element) used in the AgNPs aggregation. As a result, a well-defined linear-sweep voltammetry (LSV) peak was observed. The attachment of hCG on the electrode surface made the peptide probe lose its ability to trigger the in situ formation of the AgNPs-based network architecture on the electrode surface, thus leading to a much attenuated LSV current. The current decreased with the increase of hCG concentration ranging from 1mIU/mL to 0.2IU/mL. Consequently, a detection limit of 0.4mIU/mL was achieved. To demonstrate the amenability of our method, the contents of hCG in human serum/urine samples were determined. The results were consistent with those obtained by the enzyme linked immunosorbent assay (ELISA). Based on the well-defined and amplified electrochemical signal of the AgNPs-based network architecture, our work would also be valuable for the design of novel electrochemical sensors by marrying specific receptors.

Application of 2-(4-Formylphenyl) [60]Fulleropyrrolidine as an electrode matrix for cross linker-free immobilization of HCG-antibody and the sensing analysis

A novel fullerene derivative, 2-(4-Formylphenyl) [60]fulleropyrrolidine (FPD) has been synthesized through 1, 3-dipole cycloaddition reaction of C60 with terephthalaldehyde and glycine. The structure of the product was characterized by 1H NMR, mass spectrometry, FT-IR and UV–vis. Based on the unique zero-dimensional structure and highly active aldehyde group, the FPD was used as an electrode material for the construction of an impedimetric immunosensor for human chorionic gonadotrophin (HCG). First, the FPD was cast onto the surface of a glassy carbon electrode by the direct coating method, then the HCG antibody (anti-HCG) was covalently grafted onto electrode surface through a condensation reaction between aldehyde group of FPD and amine group of anti-HCG, without assistance of any cross-linker. Combined the high specificity of immunoreaction and high sensitivity of electrochemical impedance spectroscopy, the immunosensor shows a wide range from 0.1 to 10ngmL−1 for HCG detection. Based on 3σ, the detection limit was estimated to be 0.03ngmL−1. Satisfactory results were obtained for determination of HCG in human serum samples of the diagnostic patients, showing potential application of the proposed method in clinical diagnosis.

ELISA reader does not interfere by mobile phone radiofrequency radiation.

Background:The increasing number of mobile phones can physically cause electromagnetic interference (EMI) in medical environments; can also cause errors in immunoassays in laboratories. The ELISA readers are widely used as a useful diagnostic tool for Enzymun colorimetric assay in medicine. The aim of this study was to investigate whether the ELISA reader could be interfered by the exposure to the 900 MHz cell phones in the laboratory.Materials and Methods:Human serum samples were collected from 14 healthy donors (9 women and 5 men) and each sample was divided into four aliquots and was placed into four batches for the in-vitro quantitative determination of human chorionic gonadotropin (hCG). During colorimetric reading of the first, second, and third batches, the ELISA reader (Stat Fax 2100, Awareness Technology, Inc., USA) was exposed to 0.5, 1.0, and 2.0 W exposure of 900 MHz radiation, respectively. For the forth batch (control group), no radiation was applied. All experiments were performed comparing ELISA read out results of the I, II, and III batches with the control batch, using the Wilcoxon test with criterion level of P = 0.050.Results:The final scores in the exposed batches I, II, and III were not statistically significant relative to the control batch (P > 0.05). The results showed that 900 MHz radiation exposure did not alter the ELISA measured levels of hCG hormone in I (P = 0.219), II (P = 0.909), and III (P = 0.056) batches compared to the control batch.Conclusion:This study showed that ELISA reader does not interfere by mobile phone RF radiation at a closed contact (less than 5 cm distance). However, we recommend that medical institutions discuss these issues in the context of their specific use of technologies and frame a policy that is clear and straightforward to guide staff, patients, and visitors.

Determination of Human Chorionic Gonadotropin in Postmortem Samples in Ectopic Pregnancies.

Increased human chorionic gonadotropin levels (HCG) can be detected in femoral blood, bile, and vitreous humor collected during autopsy of pregnant women using a standard kit designed for living patients. In the study herein, the concentrations of HCG were measured in postmortem serum, vitreous, bile, cerebrospinal, and pericardial fluids in 4 cases of fatal ectopic pregnancy and 40 controls using a quantitative electrochemiluminescence immunoassay designed for living patients. No false-negative cases were identified in any of the analyzed samples in any of the ectopic pregnancy cases. No correlations were found between total HCG levels in postmortem serum and the other tested specimens. The results of this study would suggest that higher HCG in bile, vitreous, pericardial, and cerebrospinal fluids may confirm the existence of ectopic pregnancy and therefore identify other situations in which this hormone is increased, although gestational age cannot be reliably estimated using these values.

Valoración de la dosis efectiva media y sensibilidad estacional en el bufo spinulosus, usando standard internacional de gonadotrofina corionica

Usando por primera vez en nuestro país standard internacional de gonadotrofina coriónica, hemos observado modificaciones estacionales de la sensibilidad al desprendimiento de espermatozoides en el sapo común de Lima, en forma similar a la que presentan diversas especies de batracios en otros países. Los resultados hemos apreciado por la dosis efectiva teórica en U.I. para cada estación, encontrando valores D. E. 50 ó D.E.M. entre 9 y 15 U.I., con sensibilidad máxima en primavera, decreciente en verano y mínima en otoño, para volver a aumentar en invierno. Aplicando estos informes, como se comprende, se facilita en nuestro medio la determinación cuantitativa de la gonadotrofina coriónica en unidades internacionales, usando el Bufo spinulosus y con ayuda de las curvas dosis-respuestas para cada estación representadas en un diagrama, sin importar la época del año en que se trabaje. Con todo, creemos oportuno establecer que sólo es válido el método para las titulaciones en sangre y orina que se realicen en Lima; si hay la intención de aplicarlo en otras regiones del país, previamente conviene valorar en cada zona la sensibilidad específica del animal reactivo del lugar para evitar un posible error de cálculo. Por otra parte, nuestro animal de laboratorio ha resultado más sensible que sus congéneres de otros países y comparable a la que presenta la coneja, aunque menor a la rata impúber. Por ello, juzgamos conveniente usar el Bufo spinulosus para determinaciones cuantitativas cuando se busquen niveles altos de gonadotrofinas coriónicas, en tanto que no es apropiado para niveles bajos.