The routes of hysterectomy: A survey of current practices amongst members of the International Society for Gynaecologic Endoscopy (ISGE)

OBJECTIVE

This study aimed to explore the current opinion on the routes of hysterectomy amongst the members of the International Society for Gynaecologic Endoscopy (ISGE), as well as the perceptions of potential barriers that inhibit gynaecologists from offering a minimally invasive hysterectomies (MIHs) to their patients.

STUDY DESIGN

An anonymous, electronic survey was designed, including the questions about the surgeon location and length of gynaecological practice, preferred approach to hysterectomy, approximate number of surgical cases performed during the year preceding the survey (2021), and potential barriers and contraindications to performing MIHs. It was validated by 12 practicing gynaecologists. Subsequently, the survey was sent to all practicing gynaecologists who are the members of the ISGE.

RESULTS

We received a response from 159 members of ISGE (29 % response rate), of which 92 % with ≥ 5 years in practice since the completion of their residency training in Gynaecology and Obstetrics. When asked about the preferred route of hysterectomy for themselves or their relatives, 59 % chose total laparoscopic hysterectomy (TLH), 19 % vaginal hysterectomy (VH), 8 % chose laparoscopically-assisted vaginal hysterectomy (LAVH) and 5 % chose total abdominal hysterectomy (TAH). However, TAH was the most performed hysterectomy procedure undertaken by the respondents in the year preceding the survey. When asked about the main obstacles to performing MIHs, more than half of the respondents highlighted insufficient training during residency and insufficient surgical experience. Only 25 % of the responders acknowledged reading the ISGE guidelines on performing vaginal hysterectomy.

CONCLUSIONS

Contrary to a full understanding of the benefits of MIHs, lack of training, as well as insufficient surgical experience and unawareness of existing evidence-based guidelines were the main reasons for the high rate of TAH among the ISGE members who participated in the study. All efforts should be directed at teaching VH and TLH techniques during residency, continuous acquisition of practical experience, and use of validated patient selection guidelines for MIH in daily clinical practice.

Factors influencing surgical performance and learning progress in minimally invasive surgery - results of an interdisciplinary multicenter study

BACKGROUND

Advancing surgical techniques require a high level of adaptation and learning skills on the part of surgeons. The authors need selection procedures and decision support systems for the recruitment of medical students and young surgeons. The authors aimed to investigate factors influencing the surgical performance and learning abilities of surgeons and medical students.

MATERIALS AND METHODS

The training scores of persons attending 16 standardized training courses (at three training centers) of the German Working Group for Gynecological Endoscopy (AGE e.V.) from 2017 to 2020, individual characteristics, and the results of psychomotor tests of three-dimensional imagination and hand-eye coordination were correlated. Similar analyses were performed for medical students in their final clinical year from 2019 to 2020. The training concept was evaluated in a prospective, multicenter, interdisciplinary, multinational setting.

RESULTS

In all, 180 of 206 physicians (response rate 87.4%) and 261 medical students (response rate 100%) completed the multistage training concept successfully. Of personal characteristics, the strongest correlation was noted for good surgical performance and learning success, and the absolute number of performed laparoscopic surgeries ( r =0.28-0.45, P <0.001/ r =0.1-0.28, P <0.05). A high score on the spatial visualization ability test was also correlated with good surgical performance ( r =0.18-0.27, P <0.01). Among medical students with no surgical experience, however, age was negatively correlated with surgical performance, that is the higher the age, the lower the surgical performance ( r =0.13/ r =0.22, P <0.05/ P <0.001).

CONCLUSION

Individual factors (e.g. surgical experience, self-assessment, spatial visualization ability, eye-hand coordination, age) influence surgical performance and learning. Further research will be needed to create better decision support systems and selection procedures for prospective physicians. The possibilities of surgical training should be improved, promoted, and made accessible to a maximum number of surgical trainees because individual learning curves can be overcome even by less talented surgeons. Training options should be institutionalized for those attending medical school.

The influence of persistent bleeding after supracervical hysterectomy on depressive and anxious symptoms: a prospective bicenter study

PURPOSE

Postoperative spotting is a frequent adverse symptom after laparoscopic supracervical hysterectomy (LSH). The conical excision (eLSH) reduces the postoperative spotting rate, but data in a larger collective are still rare and inconsistent. The influence of persistent bleeding on the anxious and depressive symptoms has not been analyzed yet.

METHODS

311 patients, who underwent a laparoscopic supracervical hysterectomy with conical excision (n = 163), or with straight cervical resection (n = 148) were included. Anxious and depressive symptoms and postoperative spotting were recorded before operation, at 3 month follow-up and at 1 year follow-up in both operative groups using a validated questionnaire (German version of Hospital Anxiety and Depression Scale, HADS-D) and additional questions concerning the frequency and impact of bleeding. Statistical analysis included the impairment of bleeding as well as its impact on depressive and anxious symptoms for both groups.

RESULTS

11.5% after eLSH and 15.5% after LSH reported spotting after 1 year. Supracervical hysterectomy significantly improves depressive and anxious symptoms at 3 and at 12 month follow-up for both groups (p < 0.001) independent on residual spotting. Patients with a preoperative continuous bleeding showed a maximum benefit independent on operative method.

CONCLUSION

Laparoscopic supracervical hysterectomy has a positive effect on anxious and depressive symptoms in the short-term and intermediate-term follow-up. The conical excision of the cervical stump reduces postoperative spotting rate, but has no explicit advantage on symptoms of depression or anxiety, irrespective of residual postoperative spotting.

Development of a construct-based risk assessment framework for genetic engineered crops

Experience gained in the risk assessment (RA) of genetically engineered (GE) crops since their first experimental introductions in the early nineties, has increased the level of familiarity with these breeding methodologies and has motivated several agencies and expert groups worldwide to revisit the scientific criteria underlying the RA process. Along these lines, the need to engage in a scientific discussion for the case of GE crops transformed with similar constructs was recently identified in Argentina. In response to this need, the Argentine branch of the International Life Sciences Institute (ILSI Argentina) convened a tripartite working group to discuss a science-based evaluation approach for transformation events developed with genetic constructs which are identical or similar to those used in previously evaluated or approved GE crops. This discussion considered new transformation events within the same or different species and covered both environmental and food safety aspects. A construct similarity concept was defined, considering the biological function of the introduced genes. Factors like environmental and dietary exposure, familiarity with both the crop and the trait as well as the crop biology, were identified as key to inform a construct-based RA process.

Laparoscopic hysterectomy and prolapse: a multiprocedural concept

BACKGROUND AND OBJECTIVES

Today, laparoscopic intrafascial hysterectomy and laparoscopic supracervical hysterectomy are well-accepted techniques. With our multimodal concept of laparoscopic hysterectomy for benign indications, preservation of the pelvic floor as well as reconstruction of pelvic floor structures and pre-existing prolapse situations can be achieved.

METHODS

The multimodal concept consists of 3 steps: 1. Intrafascial hysterectomy with preservation of existing structures. A. Technique 1: Primary uterine artery ligation. B. Technique 2: Classic intrafascial hysterectomy. 2. A technique for the stable fixation of the vaginal or cervical stump. 3. A new method of pectopexy to correct a pre-existing descensus situation. RESULTS AND CONCLUSTION: This well-balanced concept can be used by advanced endoscopic gynecologic surgeons as well as by novices in our field.

Acidic pH and increasing [Ca(2+)] reduce the swelling of mucins in primary cultures of human cervical cells

BACKGROUND

Cervical mucus is a heterogeneous mixture of water, ions and mucins that form a hydrophilic polymer gel. Mucins, the main components of mucus, are condensed inside secretory granules and swell to become a hydrogel after exocytosis. Using human cervical secretory cell primary cultures, the effect of [Ca(2+)] and [H(+)] on the swelling velocity of mucin granules was investigated in vitro.

METHODS AND RESULTS

Immunocytochemistry demonstrated that estrogen and progesterone receptors were expressed in cultured secretory cells along with mucins type 1, 4, 5AC and 5B. Exocytosis of secretory cells, recorded by videomicroscopy, showed that during swelling, the radius of the secretory granule matrix followed first-order kinetics. An increase in extracellular [Ca(2+)] from 1 to 4 mmol/l or a reduction in pH from 7.4 to 6.5 was seen to produce a significant decrease in the velocity of swelling of the secretory granule matrix.

CONCLUSIONS

The inverse relationship observed between the diffusion of the granular matrix and the extracellular [Ca(2+)] or [H(+)] suggested that changes in cation concentration might drastically affect the swelling characteristics of mucins and provide a control mechanism for the observed viscoelastic properties of mucus.

Gonadotrophin and testosterone suppression by 7alpha-methyl-19-nortestosterone acetate administered by subdermal implant to healthy men

The synthetic androgen 7alpha-methyl-19-nortestosterone (MENT) is a potent suppressor of gonadotrophin that has several advantages for long term administration to normal or hypoandrogenic men. The aim of this study was to examine MENT serum concentrations following subdermal insertion of MENT acetate (MENT Ac) implants and their effects on gonadotrophins, testosterone, dihydrotestosterone (DHT), sex hormone-binding globulin, prostate specific antigen and insulin-like growth factor-1 serum concentrations in normal men. A total of 45 healthy men were recruited at three clinics. Each subject received one, two or four implants for 28 days. Serum samples were obtained before insertion and on days 8, 15, 22, 29, 36 and 43 after implant insertion. The average daily dose delivered in vivo by one implant was approximately 500 microg. One, two or four MENT Ac implants produced dose dependent and sustained serum MENT concentrations for the entire duration of treatment of 0.7 +/- 0.1, 1.2 +/- 0.1 and 2.0 +/- 0.1 nmol/l respectively. This treatment induced a dose dependent decrease in gonadotrophin and androgen serum levels. Two and four implants induced maximal suppression that was maintained throughout treatment and was completely reversed after removal of the implants. The mean decreases were 93 +/- 1% for testosterone, 80 +/- 3% for DHT, 97 +/- 1% for luteinizing hormone and 95 +/- 1% for follicle stimulating hormone. No serious adverse reactions were reported by the volunteers and no consistent changes in clinical chemistry and haematology were found. These results indicate that MENT Ac implants are an efficient way of MENT administration and confirm the potent gonadotrophin and androgen suppressive effect of this drug.

An ELISA specific for murine erythropoietin

Murine recombinant erythropoietin (EPO) was purified from an EPO-producing cell line and used for the production of polyclonal monospecific anti-murine EPO antibodies in rabbits. The anti-mouse EPO antibodies were purified by two affinity chromatography procedures. In order to obtain the most sensitive ELISA, different antibody combinations were tested in the ELISA sandwich assay. The best combination was achieved with an anti-human EPO antibody as coating and the biotinylated anti-murine EPO antibody as detecting antibody. With this sandwich-ELISA a sensitive standard curve in the range of 0.6-30 mU/ml could be established. The assay provides a sensitive and reliable measure of murine EPO in serum and cell culture supernatants ranging from normal to highly elevated EPO levels.

Sex hormone binding globulin expression and colocalization with estrogen receptor in the human Fallopian tube

The detection of sex hormone binding globulin (SHBG) or SHBG mRNA in several sex steroid target tissues, has raised the possibility that SHBG modulates the action of sex steroids outside the vascular compartment. The presence of SHBG mRNA was investigated by RT-PCR in the poly (A+) RNA fraction of the human Fallopian tube. Human and rat liver were used as positive and negative control tissues, respectively. The electrophoretic analysis of the amplified PCR products showed bands at 219 bp, corresponding to the expected size of the SHBG cDNA, in the Fallopian tube and human liver but not in rat liver, indicating that SHBG might be synthesized by the Fallopian tube. The cellular localization of SHBG and of estrogen receptor (ER) was examined by immunohistochemistry in consecutive sections of Fallopian tube tissues for individual staining or double immunostaining in the same section. Specific immunostaining of SHBG was present in the epithelial, vascular and muscle cells of the ampullary and isthmic region. In epithelial cells, immunoreactive SHBG was present in the apical end with the highest concentration close to the luminal membrane. The ER was localized in the nuclei of epithelial, stromal and muscle cells of the ampulla and isthmus. Double immunostaining showed that SHBG and ER are colocalized principally in epithelial cells of the ampulla and in muscle cells of the isthmus. In conclusion, the detection of SHBG and SHBG mRNA and the localization of SHBG in estrogen target cells was shown. These findings support the hypothesis that SHBG might regulate sex steroid action at the tissue level.

Pharmacokinetics and pharmacodynamics of 7alpha-methyl-19-nortestosterone after intramuscular administration in healthy men

7alpha-Methyl-19-nortestosterone (MENT) is a potent synthetic androgen that is resistant to 5alpha-reductases and therefore less prone to over-stimulate the prostate. It is a good candidate for implant administration in long-term androgen replacement therapy for hypogonadal men or as part of a male contraceptive system. To investigate the pharmacokinetics of MENT after i.m. administration, single i.m. injections of 2, 4 or 8 mg of micronized MENT were given in aqueous suspension to 18 healthy men in two clinics. Blood was sampled frequently for 8 h and 1, 2, 3, 4 and 9 days after the injections. Serum MENT concentrations were determined by radioimmunoassay. Peak MENT concentrations were dose-dependent and were reached about 1-2 h after the injections. Doubling the dose of MENT resulted in an increase of 60% in peak serum MENT concentrations. The mean +/- SE clearance rate was 1790 +/- 140 l/day. The antigonadotrophic activity of MENT was investigated by giving six consecutive daily i.m. injections of 1, 2 or 4 mg of MENT to 24 healthy men in two clinics. Blood was sampled before each injection and up to 24 days after the last injection. Serum testosterone and gonadotrophin concentrations (determined by radioimmunoassay and fluoroimmunoassay respectively) decreased in a dose-dependent and statistically significant manner. The highest dose caused a 74% fall in testosterone, a 70% fall in luteinizing hormone, and a 57% fall in follicle stimulating hormone concentrations. MENT injections did not cause any side-effects. The results show that MENT is a potent antigonadotrophic agent in men.

After-effects of a high altitude expedition on blood

The aim of the study was to investigate blood alterations caused by altitude acclimatization which last more than few days after return and might play a role for exercise performance at sea level. Measurements were performed in 12 mountaineers before, during and either 7/8 or 11/12 days after a Himalaya expedition (26-29 days at 4900 to 7600 m altitude). [Erythropoietin] rose only temporarily at altitude (max. +11 +/- 1 [SE] mu/ml serum). After return hemoglobin mass (initially 881 +/- 44 g, CO-Hb method) was increased by 14% (p < 0.01); aspartate aminotransferase activity in erythrocytes (initially 682 +/- 25 U/l) was augmented (day 7: +964 +/- 152 U/l, day 11: +533 +/- 107 U/l) indicating reduced mean cell age. Calculated blood volume (+14%) was influenced by red cell formation at altitude but also by plasma expansion at sea level. The half saturation pressure for Hb-O2 (pH 7.4, 37 degrees C) as well as the 2.3-diphosphoglycerate concentration were already initially high (32.1 +/- 0.5 mmHg, 20.5 +/- 0.7 mumol/g Hb) and showed only a nonsignificant tendency to increase after return. Also Hill's n was consistently high in the mountaineers, whereas the Bohr coefficients were slightly increased only after descent. Probably the preparatory physical training, partly in the Alps, and the stay in the Himalaya influenced O2-affinity for a prolonged time. The adaptations might reduce the loss of physical performance capacity at altitude and be part of altitude training effects.

[Early pulmonary changes caused by amiodarone]

Confluent infiltrates and interstitial condensates with (sub)segmentary spreading are typical radiological findings in amiodarone pneumopathy. A case is presented where daily amounts of 200-600 mg and a total of 18.3 g amiodarone led to alveolitis with fibrosis within 4 weeks, which is uncommon in the early stage.

Serum erythropoietin and transferrin receptor levels in patients with rheumatoid arthritis

OBJECTIVE

Rheumatoid arthritis (RA) is generally associated with mild anaemia. The role of erythropoietin (EPO) in the pathogenesis of this anaemia of chronic disorders is still a matter of controversy. Therefore, in a multicenter study we investigated the serum EPO concentration in 124 patients with rheumatoid arthritis.

METHODS

Patients with uncomplicated iron deficiency and haemolytic anaemia served as the reference group (n = 54). The measurements were performed with a specific and sensitive ELISA:

RESULTS

The mean EPO concentration +/- SD of the whole RA group (32.3 +/- 22.2 mU/ml) was elevated above normal. About 40% of the patients had underlying iron deficiency (defined by ferritin values < or = 60 ng/ml) and a significantly higher median EPO concentration than patients with normal iron stores (35.8 mU/ml versus 20.7 mU/ml; p < 0.001). The iron deficiency was associated with lower disease activity, as defined by the C reactive protein. In contrast to the reference group (r = -0.78), there was no significant correlation between EPO and the haematocrit in either RA subgroup, although the values for the RA patients were within the 95% prediction range of the reference group. In addition to the EPO, we investigated the soluble transferrin receptor level as a measure of bone marrow erythropoiesis. The level in iron-replete RA subjects was about 1.6 times higher than in normal persons, reflecting a relatively hypoproliferative erythropoietic activity.

CONCLUSION

This study shows that the EPO concentrations in RA are elevated above normal but lower than expected, and that the normal relationship between EPO and the degree of anaemia is impaired.

[Erythropoietin]

The production of red cells can be stimulated by pharmacologic doses of recombinant human erythropoietin (rHu-EPO), provided EPO-sensitive precursors and iron are available. Its side effects are negligible when used in patients with nonrenal anemia. Antibodies against rHu EPO are a rare event. Iron supplementation is routinely necessary in patients with low iron stores, since availability of iron is a rate-limiting cofactor for red cell production. The rationale for treating patients with anemia of cancer or chronic inflammation is to avoid homologous blood transfusion. However, it is not proven whether a raising of the hemoglobin concentration by 2 or 3 g% will improve the quality of life in these multimorbid patients who undergo palliative treatment. There is no evidence yet that rHu-EPO has reduced morbidity and mortality in such patients. Another question is the cost effectiveness of EPO particularly in patients who suffer from an incurable disease. EPO has also been used as an adjuvant in autologous preoperative transfusion programs and has increased the available volume of red cells for transfusion particularly in conjunction with intravenous iron supplementation. EPO given for 14 days preoperatively in patients with elective hip replacement reduced the need for transfusion by nearly 50%. A high dose of oral ferrous sulfate (300 mg) was given 11 days in advance of rHu EPO. Randomized trials are needed for patients with an initial low Hb (< 13.5 g/dl) to study the efficacy and cost effectiveness of different strategies avoiding homologous transfusion and also the risk-benefit ratio of such strategies versus homologous transfusions, since the risk of homologous transfusions has decreased considerably in recent years.

Serum erythropoietin and serum transferrin receptor levels in aplastic anaemia

Serum erythropoietin (EPO) and soluble transferrin receptor levels were serially measured in 74 patients with aplastic anaemia (AA). As control groups we investigated healthy controls (n = 24) and patients with iron-deficiency (n = 23) or haemolytic anaemia (n = 16). There was a significant negative correlation of log EPO on haematocrit both in AA patients and in the anaemic control group. However, for the same degree of anaemia, log EPO levels in AA were significantly higher than in iron-deficiency or haemolytic anaemia. EPO levels at diagnosis did not correlate with severity of aplastic anaemia, nor did they predict outcome after immunosuppression. During immunosuppressive treatment of AA with anti-thymocyte globulin and cyclosporine A, EPO levels were significantly lower compared with pre-treatment values without a corresponding change in haematocrit. This impaired EPO response to anaemia during immunosuppression might affect recovery of erythropoiesis. In AA patients, EPO levels declined with haemopoietic recovery. However, compared with normal controls, EPO levels in remission patients were still higher with respect to their haematocrit. Results of this study argue against the model of a simple feedback regulation of EPO via hypoxic anaemia. Our data support the hypothesis that cytokines and the erythropoietic progenitor pool are involved in the regulation of EPO production. The results illustrate that serial measurements of EPO along with therapeutic interventions are necessary to identify patients who might benefit from treatment with exogenous recombinant human EPO.

Erythropoetin

Mit pharmakologischen Dosen von Erythropoetin (EPO) kann, wenn Eisen und erythropoetische Vorläuferzellen verfügbar sind, ohne wesentliche Nebenwirkungen fast immer eine Erhöhung der Hämoglobinkonzentration erzielt werden. Ob sich dabei die Lebensqualität von multimorbiden Patienten mit chronischen Anämien, bei denen z.B. das Hämoglobin von 9 auf 11 g% erhöht wird, verbessert, ist in Studien zu hinterfragen. EPO ist für Indikationen, außer der renalen Anämie, bisher nicht zugelassen. EPO als Adjuvans für die autologe Blutentnahme ist bei ausreichender Eisensubstitution für gewisse Kollektive wie Frauen mit einer grenzwertig niedrigen Hämoglobinkonzentration eine mögliche Therapie, wenn auch noch eine sehr aufwendige. EPO in hoher Dosierung (300 U/kg Körpergewicht für 14 Tage) als perioperative Therapie bei ausreichender Eisensubstitution spart, wiederum unter großem finanziellem Aufwand, etwa 50% Fremdblut ein. Ein solches Verfahren ist für den Patienten, der sich einer elektiven Operation unterzieht, wenig aufwendiger als die autologe präoperative Blutentnahme, schließt aber die Anwendung von Fremdblut nicht in jedem Fall aus. Der Kosten-Nutzen-Quotient muß von uns, den behandelnden Ärzten, im Kontext einer machbaren erfolgreichen medizinischen Versorgung und der knapper werdenden Ressourcen beantwortet werden. Daher ist es notwendig, in Studien die Patienten zu identifizieren, die von einer EPO-Therapie profitieren, um letztendlich die «beste» durchführbare Therapie für den individuellen Patienten zu definieren.

Pharmacokinetics and bioavailability of ST 1435 administered by different routes

The ovulation inhibiting potency of the synthetic progestin ST 1435 (Nestorone) is high after parenteral administration and practically nil after oral administration. The purpose of this study was to determine the pharmacokinetic parameters of ST 1435 after single oral or intravenous administration or after long-term treatment with subdermal implants in women. After administration, as a single i.v. bolus, the plasma disappearance rate of immunoreactive ST 1435 had two components with half-lives (mean +/- SE) of 3.5 +/- 0.5 and 83 +/- 14 min, respectively. The volume of distribution was 4.7 +/- 1.3 L/Kg and the metabolic clearance rate was 55 +/- 6 L/Kg/d. After oral administration, the bioavailability was about 10% of the dose. After chronic subdermal administration, the plasmatic clearance was slower than following the acute doses. These results show that ST 1435 has shorter half-lives and a faster clearance rate than progestins which bind SHBG. The large volume of distribution indicates accumulation in the extravascular space and was expected in view of the high affinity of ST 1435 for progesterone receptors. The slower plasma elimination rate after chronic administration was attributed to the re-entry of a larger mass of drug from the extravascular space, and/or accumulation of immunoreactive metabolites with slower clearance than the parent steroid.

Tissue uptake of human sex hormone-binding globulin and its influence on ligand kinetics in the adult female rat

The distribution of human sex hormone-binding globulin (hSHBG) and its influence upon the kinetics of its ligands were assessed in the adult female rat, which lacks a comparable protein in serum. Purified hSHBG was administered i.v. to adult female rats as a single bolus. The plasma disappearance rate of immunoreactive hSHBG had one component with a half-life of 15 h. The estradiol (E2) binding activity of serum attributable to hSHBG was elevated 2-fold; during a continuous infusion of E2, hSHBG increased E2 serum levels above those of control infused animals. Treatment with hSHBG did not modify the plasma clearance of endogenous E2, but accelerated the disappearance rate of 5 alpha-dihydrotestosterone (DHT). In animals injected with a tracer dose of radioactive steroids, pretreatment with hSHBG increased uterine and oviductal accumulation of E2- but not DHT-associated radioactivity. This effect was specific to some E2 target tissues since hSHBG did not alter the concentration of E2- or DHT-associated radioactivity in the hypophysis, liver, diaphragm, or brain. Treatment with anti-E2 antibodies, which elevated E2 binding activity in serum, decreased the accumulation of E2-associated radioactivity in uterus and oviduct. Immunofluorescent localization of hSHBG revealed intense labeling of the uterine and oviductal epithelium. We conclude that this foreign hormone-binding globulin introduced in serum at concentrations that have minimal circulating reservoir effect on E2 can reach intracellular domains and affect the concentration of this ligand in target tissues.

A sensitive sandwich ELISA for measuring erythropoietin in human serum

A sandwich, non-competitive enzyme-linked immunosorbent assay (ELISA) for erythropoietin (EPO) is described. The ELISA utilizes a monospecific, polyclonal antibody raised in rabbits against human recombinant EPO (rhu EPO) and purified over a rhu EPO affinity chromatography column. The ELISA procedure can be summarized as follows: Anti-EPO is coated onto 96-well ELISA microtitre plates; standard EPO or sample is added and left to bind to this catching antibody; this is followed by the addition of the same antibody which has been biotinylated; finally, anti-biotin conjugated to alkaline phosphatase is added and the enzyme reaction developed and read at 405 nm. All parameters of the assay have been optimized. Recombinant human EPO was standardized against the World Health Organization 2nd International Reference Preparation for erythropoietin. The minimal detectable concentration of rhu EPO was 0.3-0.5 mU/ml, which corresponded to 1.2-2 mU/ml of EPO in serum (serum diluted 1:4). No reaction was obtained with a variety of blood components and cytokines, indicating that the anti-EPO antibody did not cross-react with those substances to produce false-positive results. The intra-assay variation ranged from 3% to 10%, while the inter-assay variation ranged from 8.5% to 24%. Serum dose-response curves were parallel to the standard dose-response curve. The assay is easy to use, rapid, reproducible, but above all quantitative, specific and sensitive to measure the EPO content in all serum samples.

Changes in serum levels of SHBG, endogenous ligands and levonorgestrel induced by ethinylestradiol in Norplant users

This work was done in search for a model to examine target organ response to fluctuations in serum levels of sex hormone-binding globulin (SHBG) and its ligands. The time course and magnitude of fluctuations of SHBG, levonorgestrel (L-Ng), estradiol (E2), testosterone (T) and dihydrotestosterone (DHT) in serum were examined during and after treatment with 50 ug of ethinylestradiol (EE2) daily for 10 days in 10 volunteer women using NORPLANT implants. Six of these volunteers were also treated with 20 ug of EE2 daily for 7 days and two additional volunteers using a copper-T IUD were treated with 50 ug of EE2 daily for 7 days. In all cases, SHBG and L-Ng levels increased in a close parallel manner several-fold above basal levels during treatment, reaching a maximum around two days after the last EE2 pill. In contrast, the levels of E2 and T increased in one subject, decreased in 5 and remained unchanged in 4, while changes of DHT were unrelated to those of the other ligands. Since the L-Ng "secretion rate" by NORPLANT implants is constant, it follows that the effect of EE2 on its levels is due to a decreased metabolic clearance rate, most likely secondary to the increased binding of L-Ng to SHBG in serum. This interpretation is in agreement with the close parallelism in the fluctuations of L-Ng and SHBG. It is concluded that in NORPLANT users, SHBG and L-Ng, but not the endogenous ligands, behave in a predictable manner in response to EE2. Thus, this model affords the possibility of exploring the influence of SHBG on tissue response to progestins.

[Hypocortisolemia with neither signs nor symptoms of cortisol deficiency: research on transcortin characteristics]

Low plasma levels of cortisol, as a result of primary or secondary adrenal hypofunction, is usually associated to findings of hypocortisolism. Low plasma cortisol levels without clinical manifestations have been observed in patients in which cortisol binding capacity (CBG) is altered. In this paper we report a clinically normal patient, with very low plasma cortisol levels. We investigated a possible CBG defect or the presence of a CBG binding substance as an explanation of the clinical findings. We found a normal CBG and no competing substance. Therefore, the presence of low cortisol levels suggests the presence in this patient of a receptor with increased sensitivity to cortisol, or another molecule that can be recognized as glucocorticoid by the cortisol receptor.

The use of sequence-specific antibodies to identify a secondary binding site in thrombin

The peptide comprising residues 62-73 of the B-chain of human alpha-thrombin was synthesized and polyclonal antibodies raised against it. These antibodies were found to bind to the synthetic peptide, a CNBr fragment, and a proteolytic subfragment containing this sequence, as well as the entire thrombin molecule. The purified antibodies had no effect on the hydrolysis by thrombin of D-Phe-pipecolyl-Arg-p-nitroanilide and caused only a minimal decrease (20%) in the second-order rate constant for inactivation by antithrombin III. On the other hand, the antibodies competitively inhibited the binding of hirudin over the concentration range tested (0-43 nM), and a dissociation constant of 3.4 +/- 0.5 nM was found for the antibodies. The release of fibrinopeptide A from the A alpha-chain of fibrinogen by thrombin was competitively inhibited with an inhibition constant of 11.7 +/- 0.4 nM. The activation of protein C by thrombin in the presence of thrombomodulin was also inhibited by the antibodies, and an apparent inhibition constant of 10.7 +/- 1.5 nM was found. In contrast, the antibodies had no effect on the activation of protein C in the absence of thrombomodulin. These results are discussed in relation to data obtained recently on the interaction of well defined proteolytic derivatives of human alpha-thrombin with the ligands described above.

Evidence for a transcellular component to the transepithelial sodium efflux in toad skin

The transepithelial efflux of sodium, from the inner to the outer surface was measured across the isolated toad skin, mostly after abolition of the electrochemical gradient. The effects on this efflux of several agents and manipulations were studied in order to make a distinction between the paracellular component and a hypothetical transcellular one. Amiloride decreased the transepithelial efflux, while ouabain and cyanide increased it. From the known mode of action of those agents, it was inferred that part of the efflux occurred across the cell. Removal of sodium from the external solution interfered apparently with both components of the transepithelial efflux, while the action of external hypertonicity seemed to be restricted to the paracellular shunt pathway. Access of sodium from the internal solution to the active transport pool is thus suggested, with consequent increase in metabolic cost of transport. Yet, compared with the net influx, the amounts involved are very small; consequently, they escape detection by oxygen consumption measurements.

Oxygen consumption by frog skin and its isolated epithelial layers as a function of their sodium-transporting activity

The metabolic cost (in terms of oxygen consumption) of transcellular sodium transport was assessed on ventral frog skin and its isolated epithelial layers, by measuring the decrease in oxygen consumption by the tissue upon transient withdrawal of sodium from the outside solution. The same number of sodium ions was transported per molecule oxygen consumed whole skin (17.4 +/- 2.3) and its isolated epithelium (17.3 +/- 2.4). The metabolic cost of sodium transport could not be estimated properly when this process was blocked by amiloride or ouabain, as these drugs were found to bring about an increase in oxygen consumpton by the tissue when no sodium was available for transport.