Myocardial Strain for the Differentiation of Myocardial Involvement in the Post-Acute Sequelae of COVID-19-A Multiparametric Cardiac MRI Study

Myocardial involvement was shown to be associated with an unfavorable prognosis in patients with COVID-19, which could lead to fatal outcomes as in myocardial injury-induced arrhythmias and sudden cardiac death. We hypothesized that magnetic resonance imaging (MRI) myocardial strain parameters are sensitive markers for identifying subclinical cardiac dysfunction associated with myocardial involvement in the post-acute sequelae of COVID-19 (PASC). This study evaluated 115 subjects, including 65 consecutive COVID-19 patients, using MRI for the assessment of either post-COVID-19 myocarditis or other cardiomyopathies. Subjects were categorized, based on the results of the MRI exams, as having either 'suspected' or 'excluded' myocarditis. A control group of 50 matched individuals was studied. Along with parameters of global cardiac function, the MRI images were analyzed for measurements of the myocardial T1, T2, extracellular volume (ECV), strain, and strain rate. Based on the MRI late gadolinium enhancement and T1/T2/ECV mappings, myocarditis was suspected in 7 out of 22 patients referred due to concern of myocarditis and in 9 out of 43 patients referred due to concern of cardiomyopathies. The myocardial global longitudinal, circumferential, and radial strains and strain rates in the suspected myocarditis group were significantly smaller than those in the excluded myocarditis group, which in turn were significantly smaller than those in the control group. The results showed significant correlations between the strain, strain rate, and global cardiac function parameters. In conclusion, this study emphasizes the value of multiparametric MRI for differentiating patients with myocardial involvement in the PASC based on changes in the myocardial contractility pattern and tissue structure.

Real-Time Strain-Encoding Cardiovascular MRI for Assessment of Regional Heart Function in Tetralogy of Fallot Patients

BACKGROUND

Tetralogy of Fallot (ToF) is the most common form of cyanotic congenital heart disease, where right ventricular (RV) function is an important determinant of subsequent intervention.

OBJECTIVE

In this study, we evaluate the feasibility of fast strain-encoding (fastSENC; a one-heartbeat sequence) magnetic resonance imaging (MRI) for assessing regional cardiac function in ToF.

METHOD

FastSENC was implemented to characterize regional circumferential (Ecc) and longitudinal (Ell) strains in the left ventricle (LV) and RV in post-repair ToF. Data analysis was conducted to compare strain measurements in the RV to those in the LV, as well as to those generated by the MRI Tissue-Tracking (MRI-TT) technique, and to assess the relationship between strain and ejection fraction (EF).

RESULTS

Despite normal LVEF (55±8.5%), RVEF was borderline (46±6.4%), but significantly lower than LVEF. RV strains (RV-Ell=-20.2±2.9%, RV-Ecc=-15.7±6.4%) were less than LV strains (LV-Ell=-21.7±3.7%, LV-Ecc=-18.3±4.7%), and Ell was the dominant strain component. Strain differences between fastSENC and MRI-TT were less significant in RV than in LV. There existed moderate and weak correlations for RV-Ecc and RV-Ell, respectively, against RVEF. Compared to LV strain, RV strain showed regional heterogeneity with a trend for reduced strain from the inferior to anterior regions. Inter-ventricular strain delay was larger for Ell (64±47ms) compared to Ecc (36±40ms), reflecting a trend for contraction dyssynchrony.

CONCLUSION

FastSENC allows for characterizing subclinical regional RV dysfunction in ToF. Due to its sensitivity for evaluating regional myocardial contractility patterns and real-time imaging capability without the need for breath-holding, fastSENC makes it more suitable for evaluating RV function in ToF.

Myocardial Contractility Pattern Characterization in Radiation-Induced Cardiotoxicity Using Magnetic Resonance Imaging: A Pilot Study with ContractiX

Radiation therapy (RT) plays an integral role in treating thoracic cancers, despite the risk of radiation-induced cardiotoxicity. We hypothesize that our newly developed magnetic resonance imaging (MRI)-based contractility index (ContractiX) is a sensitive marker for early detection of RT-induced cardiotoxicity in a preclinical rat model of thoracic cancer RT. Adult salt-sensitive rats received image-guided heart RT and were imaged with MRI at 8 weeks and 10 weeks post-RT or sham. The MRI exam included cine and tagging sequences to measure left-ventricular ejection fraction (LVEF), mass, myocardial strain, and ContractiX. Furthermore, ventricular torsion, diastolic strain rate, and mechanical dyssynchrony were measured. Statistical analyses were performed between the sham, 8 weeks post-RT, and 10 weeks post-RT MRI parameters. The results showed that both LVEF and myocardial mass increased post-RT. Peak systolic strain and ContractiX significantly decreased post-RT, with a more relative reduction in ContractiX compared to strain. ContractiX showed an inverse nonlinear relationship with LVEF and continuously decreased with time post-RT. While early diastolic strain rate and mechanical dyssynchrony significantly changed post-RT, ventricular torsion changes were not significant post-RT. In conclusion, ContractiX measured via non-contrast MRI is a sensitive early marker for the detection of subclinical cardiac dysfunction post-RT, and it is superior to other MRI cardiac measures.

The EMA review of trastuzumab emtansine (T-DM1) for the adjuvant treatment of adult patients with HER2-positive early breast cancer

Trastuzumab emtansine (T-DM1) is an antibody-drug conjugate of trastuzumab [a monoclonal antibody against human epidermal growth factor receptor 2 (HER2)] and DM1 (an inhibitor of tubulin polymerisation). It was initially approved in the European Union for the treatment of adult patients with HER2-positive unresectable locally advanced or metastatic breast cancer (BC) who had previously received trastuzumab and taxanes. On 18 December 2019, a variation of the marketing authorisation was approved extending this use to the adjuvant therapy of adult patients with HER2-positive early BC who have residual invasive disease in the breast and/or lymph nodes after neoadjuvant taxane-based and HER2-targeted therapy. A phase III randomised, multicentre, open-label trial compared T-DM1 with trastuzumab as adjuvant therapy in patients with HER2-positive early BC who had received preoperative chemotherapy and HER2-targeted therapy followed by surgery, with a finding of invasive residual disease in the breast and/or axillary lymph nodes. The study met its primary endpoint by showing an increased 3-year invasive disease-free survival rate in the T-DM1 arm (88.3%) compared with the trastuzumab arm (77.0%), with an unstratified hazard ratio of 0.50 (95% confidence interval: 0.39-0.64). There was a higher incidence of hepatotoxicity (37.3% versus 10.6%), thrombocytopenia (28.5% versus 2.4%), peripheral neuropathy (32.3% versus 16.9%), haemorrhage (29.2% versus 9.6%) and pulmonary toxicity (2.8% versus 0.8%) in the T-DM1 arm compared with the control arm. The aim of this manuscript was to summarise the scientific review of the application leading to regulatory approval of this additional indication in the European Union.

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T-DM1 was approved for the adjuvant therapy of HER2+ early BC not in pathological complete response after taxanes + anti-HER2 neoadjuvant therapy.

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A phase III randomised trial revealed an increased 3-year invasive disease-free survival rate in patients receiving T-DM1 compared with trastuzumab.

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Patients receiving T-DM1 experienced more hepatotoxicity, thrombocytopenia, neuropathy, bleeding and lung toxicity.

New insights into molecular aspects of sperm-oviductal binding in Egyptian buffaloes using an in vitro model: Effects of oviductal segments and media

We aimed (I) to simulate an in vivo milieu, through establishing an in vitro paradigm to study sperm-oviductal interactions using different segments of oviduct, as well as different incubation media, and (II) to investigate spatial changes of oviductal gene expression. Two experiments were designed; one was to investigate the yield of oviduct aggregates from different oviduct segments; in the second experiment, we observed effects of different incubation media on sperm-oviductal binding. Oviduct cell pellets before (control) and after sperm binding were collected for RNA isolation and gene expression. Isthmus resulted in a higher aggregate yield and possessed the highest affinity towards spermatozoa. The different segments of oviduct showed clear changes in gene expression after sperm binding. TALP medium promoted formation of a higher number of oviduct aggregates towards spermatozoa. Different media resulted in profound alterations in isthmus gene expression. Collectively, isthmus segment in TALP media showed the highest binding affinity to spermatozoa. At the molecular level, our in vitro model was successful for simulation in vivo milieu. Thus, our findings could be used as a simple tool to gain more insights into the molecular regulation of sperm movement, selection and affinity for oviductal binding in buffaloes.

Evaluation of the influence of main groundwater ions on arsenic removal by limestones through column experiments

The influence of common groundwater major ions on arsenic (As) retention by native limestones was studied through column experiments. Columns were packed with rock particles (0.5-1.41 mm) and fed with solutions containing As, and chloride (Cl), sulfate, bicarbonate or fluoride (F) in concentrations similar to those measured in one of the most As-rich wells of Mexico. Besides, other solutions were also treated containing multiples or submultiples of those anion concentrations. Physico-chemical parameters, As, and each anion concentrations were determined weekly along 4 months. After the end of the experiments rocks collected from the top of the columns were analyzed by XRF, XRD, and SEM-WDS. Concentrations of As decreased from 1.2 mg/L to values below the Mexican drinking water standard (0.025 mg/L), since the first week in the solutions containing F or Cl keeping low values afterwards, indicating that they do not interfere with As removal. However, although As strongly decreased in the solutions containing sulfate since the first week, it started to increase from the 12th week in the highest concentrated solution. Bicarbonate was the anion affecting most As retention, since, after its decrease below 0.025 mg/L in the 2nd week for both solutions (30 mg/L and 300 mg/L), it started to increase since the 7th week in the most concentrated one, but maintained a low concentration in the least concentrated solution. Saturation index calculations and XRD analyses did not evidence the formation of As minerals. However, SEM elemental maps and XRF analyses showed the presence of As on the rocks after the treatments. Results indicate that As may be retained by sorption. Sulfate and bicarbonate compete with As for sorption sites. Results showed that native limestones are an option for treating As polluted water. Experiments also indicated that bicarbonate and sulfate may interfere with As removal depending on their concentrations.

Multiresidue method for trace pesticide analysis in honeybee wax comb by GC-QqQ-MS

The aim of this analytical study is to develop an improved multi-residue methodology of high sensitivity and expanded scope for pesticide residue analysis in honeybee wax combs. The method was validated for 160 pesticide residues (including acaricides, insecticides, fungicides and herbicides) gas chromatography amenable and covering a wide variety of polarity and chemical structure. This method of analysis applied gas chromatography coupled to a triple quadrupole mass spectrometer for the quantitative analysis of pesticide residues. The extraction procedure applied was based QuEChERs method allowing acceptable recoveries for most of the pesticides (98%), within the range 60-120% with an associated precision (RSD) <20%, at concentration levels of MQL of 10µgkg^-1 for all pesticides with the exception of 3,5-dichloroaniline and chlordane (20µgkg^-1). The expanded uncertainty of the results was ±35% on average (coverage factor k=2 for a confidence level of 95%). The chromatographic multi-residue method was applied to determine levels of pesticide residues in 50 honeybee wax comb samples randomly collected from different apiaries in Spain. A total of 32 pesticide residues (14 insecticides/acaricides, 10 insecticides, 6 fungicides and 2 herbicides) were detected in the samples. The highest pesticide concentrations were found for those with insecticide-acaricide activity like acrinathrin, chlorfenvinphos, coumaphos and fluvalinate-tau, some of them are mainly applied in apiculture for controlling the honeybee parasite Varroa destructor. The total load of pesticide residues ranged from 69 to 1000µgkg^-1 for 40% of the analysed samples, 22% contained pesticide residues in the ranges of 1000-2000µgkg^-1, 24% between 2000 and 5000µgkg^-1 and 14% of the samples contained residues between 5000 and 9557µgkg^-1.

An overview of the new test stand for H⁻ ion sources at FNAL

A new test stand at Fermi National Accelerator Laboratory (FNAL) is being constructed to carry out experiments to develop and upgrade the present magnetron-type sources of H(-) ions of up to 80 mA at 35 keV in the context of the Proton Improvement Plan. The aim of this plan is to provide high-power proton beams for the experiments at FNAL. The technical details of the construction and layout of this test stand are presented, along with a prospective set of diagnostics to monitor the sources.

Antibacterial activity of extracts of acacia aroma against methicillin-resistant and methicillin-sensitive Staphylococcus

Antibacterial activity of organic and aqueous extracts of Acacia aroma was evaluated against methicillin-resistant Staphylococcus aureus (MRSA), methicillin sensitive Staphylococcus aureus (MSSA) and methicillin-resistant Staphylococcus epidermidis. Inhibition of bacterial growth was determined using agar diffusion and bioautographic methods. Among all assayed organic extracts only ethanolic and ethyl acetate extracts presented highest activities against all tested Staphylococcus strains with minimal inhibitory concentration (MIC) values ranging from 2.5 to 10 mg/ml and from 2.5 to 5 mg/ml respectively. The aqueous extracts show little antibacterial activity against Staphylococcus strains. The bioautography assay demonstrated well-defined growth inhibition zones against S. aureus in correspondence with flavonoids and saponins. A. aroma would be an interesting topic for further study and possibly for an alternative treatment for skin infections.

Cutaneous leishmaniasis due to Leishmania chagasi/Le. infantum in an endemic area of Guarico State, Venezuela

This study reports cutaneous leishmaniasis (CL) caused by Leishmania chagasi/Le. infantum in Venezuela, with some atypical characteristics. Out of 63 cases of CL in the suburbs of Altagracia de Orituco, Guarico State, Venezuela, 30 presented clinical, parasitological, immunological and epidemiological features different from those of the classical CL known in the country. The initial lesion was small and nodular, which, if not treated, might progress to a superficial ulcer. No secondary infection was observed. The identification of the isolates was carried out by molecular techniques. Twelve species of phlebotomine sandflies were caught, the most abundant being Lutzomyia evansi and Lu. longipalpis s.l., known vectors of Le. chagasi/Le. infantum. The existence of Le. chagasi/Le. infantum and its vectors in an endemic area of CL has implications and we suggest that epidemiological studies should be carried out to obtain a clearer picture of the extent of this CL form in Venezuela.

[Effect to the serotonin transporter gene (5-HTT) on personality dimensions in individuals without psychopathology]

INTRODUCTION

The aim of the present study was to assess the association between the serotonin transporter gene and the Temperament and Character Inventory (TCI) personality dimensions in subjects without psychopathology.

METHOD

Fifty seven individuals without psychiatric symptoms were assessed with the SCL-90, and the TCI. In all subjects a peripheral blood sample was taken to determine their genotypes, after informed consent. Three groups were formed according to the 5-HTT genotype: SS, SL and LL, and the TCI results were compared.

RESULTS

There was no association among the 5-HTT genotypes and any of the TCI subscales. There were also no statistical differences among any of the three groups divided by genotype only according to the TCI scores, as well as when compared with historical controls.

CONCLUSIONS

These results are consistent with other studies that have not found associations among the different measurements of personality and 5-HTT genotypes. Likewise, our data suggest that our sample can be useful as a source of controls for later studies. This is the first study assessing TCI dimensions and the 5-HTT gene in the Mexican population.

ABV (doxorubicin [Adriamycin], bleomicin and vincristine) polychemotherapy regimen in HIV Kaposi’s Sarcoma: Uruguaian 10-year experience

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Background: Kaposi’s sarcoma is the most common malignancy among HIV patients and is considered to be one of the AIDS defining conditions. This abstract illustrates our 10 year experience with the treatment of 32 Kaposi’s sarcoma HIV patients with the same therapeutic approach. Methods: Between 04/95 and 03/05 we recruited 32 previously untreated patients that were diagnosed with Kaposi’s sarcoma and treated at the Servicio de Oncologia Clinica (Universitary Clinicas Hospital) in Montevideo. All of them received the same iv polychemotherapy plan (Adriamycin 10mg/m2, Bleomycin 10 U/m2 and Vincristine 1.4 mg/m2, every two weeks until tumor progression or severe toxicity). Results: 21 of the patients were good risk ones and the remaining 11 were poor risk patients (AIDS Clinical Trials Group staging classification). CD4 levels varied from 6 to 780/ml and the viral load ranges were 240 to 89000 copies. The patients received an average of 10.2 (4–21) polychemotherapy cycles. Grade 3–4 myelotoxicity was reported in 5 patients delaying the onset of the subsequent cycles. Grade 2 neurotoxicity was seen in 7 patients after 4, 5, 6, 8, 10, 11 and 13 cycles of ABV, changing vincristine for vinblastine (4mg/m2 every two weeks) in these patients. All the patients achieved a partial response with improvements in CD4 levels and viral load. 13/32 patients experienced a relapse (3–29 months after last chemotherapy cycle). 3 patients were retreated with paclitaxel 135 mg/m2 with 2/3 new partial responses of shorter duration. 5 patients received 4 additional ABV cycles achieving a new partial response. 5 patients refused further treatment dying due to progressive disease. One relapsed patient developed a second malignancy (High grade Non Hodgkin lymphoma) dying three months later. Conclusions: These data suggest that ABV regimen is still an effective treatment option for HIV-Kaposi’s sarcoma, specially in the undeveloped countries in which the cost of other better internationally approved options (liposomal doxorubicin and daunorubicin) makes them unaccesible for the majority of the population.

No significant financial relationships to disclose.

Metabolic changes in DOCA-salt hypertensive rats

In a previous report, we observed an altered proportion of fiber types and a reduction of capillary per fiber ratio in extensor digitorus longus (EDL) and soleus (SOL) muscles of deoxicorticosterone acetate (DOCA)-salt hypertensive rats when compared with controls. The aim of the present study was to ascertain various carbohydrate and lipid enzyme activities and substrates that may be involved in the morphological changes reported. In the SOL muscle of hypertensive rats, glucose, glycogen and triglycerides (TG) levels were increased, citrate synthase (CS) and beta-hydroxy-acyl-CoA dehydrogenase (HAD) activities were reduced, while hexokinase (HK) and lipoprotein lipase (LPL), LPL mass, lactate and free fatty acids (FFA) levels were unchanged. In EDL muscles of hypertensive rats, glycogen levels and LPL mass were higher than in controls, while CS, HAD, HK, and LPL activities and glucose, lactate, FFA and TG levels were unmodified. Serum levels of insulin, TG, cholesterol and FFA were increased while glucose levels were decreased and high-density lipoprotein-cholesterol levels were similar in hypertensive rats when compared with controls. In conclusion, hypertensive rats showed increased glycogen in both EDL and SOL muscles, with hyperinsulinemia and reduced glycemia. Hyperinsulinemia might have been a compensatory response to insulin resistance. The oxidative capacity of SOL muscle was reduced indicating that glucose uptake was conduced via non-oxidative metabolism. TG, FFA and cholesterol were increased in serum and TG in SOL muscle.

[Hepatitis A virus infection in children in Argentina: a pilot study]

The severity and/or the prognostic of infections with the hepatitis A virus (HAV) is related to the age at which the infection occurs. Since transmission of the virus occurs by the fecal-oral route, the prevalence and age-relate incidence of infection is determined by the adequacy of sanitation hygienic measures and the socio economic level of exposed populations. Thus, the disease is having an increasing impact in developing countries with improving sanitary standards whereas inhabitants of industrialized countries are particularly at risk while visiting under-developed countries. We have established a cooperative group for the serologic study of children range between six months to ten years old, without sintomatology of acute hepatitis. The patients live in Buenos Aires, San Justo, Trelew, Rosario and Tucumán cities. We studied 3699 children. The specific Ab-antiHAV IgG were measured by enzyme immunoassay with commercial available kits (Organon and-or Abbott). The variable of study were age, sex and water quality.

RESULTS

45.19% were of San Justo, 26.15% of Rosario, 13% of Buenos Aires, 8.37% of Trelew and 7.29% of Tucumán. We observed the highest of possibility percentage (%POS) in Tucumán (81.4%), followed by San Justo (57.8%), Rosario (46.5%), Trelew (41.99%) and Buenos Aires (29.4%). In all the cities the lowest %POS was found in children under three years old. Between three and six years old the results were variable and an increase in %POS was observed related to the growth. The global %POS was 51.56%.

CONCLUSIONS

This study confirms Argentina as a high endemic country for HAV infection. A global vaccination program is the only strategy that has the potential to prevent recurrent epidemics of hepatitis A and its erradication.

Capillary and muscle fiber type changes in DOCA-salt hypertensive rats

BACKGROUND

Discrepancies concerning the effect of hypertension on capillaries and muscle fiber types in skeletal muscle have been reported. This study demonstrates the effects of hypertension produced by deoxicorticosterone acetate (DOCA) and salt load on the extensor digitorum longus (EDL) and soleus muscles of the rat.

METHODS

Hypertension was produced by subcutaneous injections of DOCA and supplemented with drinking 1% NaCl solution. One group was treated for 7 weeks and another for 14 weeks. Fiber types were classified by ATPase reaction at pH 4.35, capillaries were counted in alpha-amylase-PAS-stained sections, and ultrastructure was studied by conventional methods of transmission electron microscopy.

RESULTS

In the 7-week group, a decrease in the percentage of IIA, with an increase in IIB and I fiber types, was found in the EDL muscle. Capillary density was not reduced, but endothelial cells showed surface infoldings into the lumen. Altered mitochondria and an infiltrate of macrophages was present in pericytes. In the 14-week group, a decrease in capillary to fiber index was found in both soleus and EDL muscles. EDL fiber type changes were the same as at 7 weeks. The soleus muscle showed an increased percentage of type I fibers. Some capillaries were degenerated, and others showed an increase in the endothelial cell area covered with pericytes, which resembled smooth muscle cells.

CONCLUSION

Hypertensive rats showed changes in the percentage of fiber types in the soleus and EDL muscles. Capillaries adjacent to muscle fibers were reduced and showed morphological changes that resembled arterioles.

H+/PPi stoichiometry of membrane-bound pyrophosphatase of Rhodospirillum rubrum

Two kinetic methods have been used to measure the H+/PPi stoichiometry in the chromatophores of the photosynthetic bacteria Rhodospirillum rubrum. In the first method, the fluorescent probe acridine orange was employed to infer the proton pump activity at the steady state of the delta pH generation. At this point the translocation of protons by the H(+)-PPiase in one direction is balanced exactly by the leak of protons in the opposite direction. Pyrophosphatase activity was then quickly stopped by adding EDTA, producing a relaxation of delta pH. From the initial rate of this relaxation and the rate of PPi hydrolysis measured under the same condition, the H+/PPi stoichiometry was obtained. In the second method, a mathematical model was used to describe the time course of delta pH formation. In the two methods an apparent H+/PPi stoichiometry of nearly 2 was obtained. The H+/ATP stoichiometry was determined also as an internal control, giving a value of nearly 3.6, which is in agreement with the value in different F-type H(+)-ATPases.

Double staining of coomassie blue-stained polyacrylamide gels by imidazole-sodium dodecyl sulfate-zinc reverse staining: sensitive detection of coomassie blue-undetected proteins

The sensitivity, simplicity, and relative rapidity of Coomassie blue staining have made this technique the method of choice for routine detection and quantitative analysis of gel electrophoresis-separated protein bands in many applications. To extend the usefulness of this technique, we have developed a new double-staining method for visualizing SDS-PAGE-separated protein bands that were undetected by Coomassie blue staining of the gel. Coomassie blue-stained gels are washed in distilled water (15 min, two times) and then subjected to imidazole-zinc reverse staining. As a result of the method, a homogeneous white-stained background is generated and two types of protein bands can be observed: (a) typical Coomassie blue-stained bands, which appear superposed on larger transparent bands; and (b) reverse-stained (transparent) bands, which were previously undetected by the Coomassie blue staining. The method is rapid, simple, and reproducible and double-staining gels can be kept in distilled water for months without loss of the protein pattern. The overall sensitivity is high (e.g., 1.6 ng for recombinant streptokinase, 47 kDa) over a wide range of protein molecular weights (10 to 100 kDa) and independent of the degree of Coomassie blue destaining of the gel. Furthermore, a mechanism offering a consistent explanation for the role of imidazole, SDS, and zinc in the reverse staining of gels, particularly after Coomassie blue staining is proposed.

Surface charge modifications do not affect the hydrolytic activity of membrane-bound pyrophosphatase of Rhodospirillum rubrum

The surface charge of the membrane of chromatophores of Rhodospirillum rubrum was modified by two methods: fusion of liposomes with the membrane of the chromatophore by changing the pH and by incubating chromatophores in the presence of cationic or anionic detergents. The hydrolytic activity of membrane-bound pyrophosphatase, on surface charge modified chromatophores, did not change the Km of the enzyme for its substrate (Mg-PPi2-) nor the activation effect of free Mg2+ on the hydrolytic activity. This membrane enzyme is not regulated by surface charge.

Mg2+ is an essential activator of hydrolytic activity of membrane-bound pyrophosphatase of Rhodospirillum rubrum

The substrate for the hydrolytic activity of membrane-bound pyrophosphatase is the PP(i)-Mg2+ complex. The enzyme has no activity when the free Mg2+ concentration is lower than 10 microM (at 0.5 mM-PP(i)-Mg2+), and therefore free Mg2+ is an essential activator of the hydrolytic activity. The Km for the substrate changes in response to variation in free Mg2+ concentration, from 10.25 to 0.6 mM when free Mg2+ is increased from 0.03 to 1.0 mM respectively. The Km for Mg2+ depends on the substrate concentration: the Km decreases from 0.52 to 0.14 mM from 0.25 to 0.75 mM-PP(i)-Mg2+ respectively. The extrapolated Km for Mg2+ in the absence of the substrate is 0.73 mM. Imidodiphosphate-Mg2+ and free Ca2+ were used as competitive inhibitors of substrate and activator respectively. The equilibrium binding kinetics suggest an ordered mechanism for the activator and the substrate: Mg2+ ions bind the enzyme before PP(i)-Mg2+ in the formation of the catalytic complex, membrane-bound pyrophosphatase-(Mg2+)-(PP(i)-Mg2+).

The evaluation of 186Re-labeled antibodies using N2S4 chelate in vitro and in vivo using tumor-bearing nude mice

We have recently described a method for radiolabeling monoclonal antibodies, with metallic radionuclides using a new chelating agent N2S3. Using this chelate the monoclonal antibodies Lym-1 and B72.3 were labeled with 186Re and their biological integrity was evaluated in vitro and in vivo. 186Re-labeled antibodies using N2S4 methodology were found to be stable in human serum and retained their immunoreactivity. Intravenous administration of 0.5 mCi 186Re-labeled antibodies resulted in partial or complete regression of tumor tissue in mice.

Cytoplasmic estradiol binding sites in testis of fertile and infertile men

Free cytoplasmic estradiol receptor was determined in testicular biopsies from six adults showing various primary testicular disorders, and in testicular tissue obtained at autopsy from 18 males of various ages. Estradiol receptors were found in all cases examined. Receptor concentration varied during testicular maturation and from one patient to another. The presence of the receptor at an early stage of development and the changes observed in its concentration during testicular maturation and dysfunction support the idea that estradiol may play, through its receptor interaction, an important role in the regulation of testicular steroidogenesis during postnatal human development.

The inability of in vitro transforming SV40 subgenomes to cause tumors in vivo

Linear or subgenomic SV40 DNAs were transfected into cells from a variety of species (including rodent, dog, muntjak, and monkey) and injected subcutaneously into neonate Syrian hamsters for tumorigenicity testing. The 'early-region' subgenomes were capable of transforming cells in vitro. Complete genomes or complementary subgenomes could transform nonpermissive and semipermissive cells, were infectious for permissive cells, and induced tumors from which infectious virus could be rescued. Tumors were not formed in neonate hamsters upon injection with subgenomic SV40 DNAs, even those capable of transforming cells in vitro. These results suggested that SV40 tumor formation in vivo may require a complete genome.

Bacteroides fragilis resistance to clindamycin in vitro

Clindamycin resistance in Bacteroides fragilis was examined in 507 strains isolated from 1973 to 1981. Three groups were recognized: highly susceptible (minimum inhibitory concentration [MIC] less than or equal to 0.125 microgram/ml), intermediately susceptible (MIC = 0.25 to 4 micrograms/ml), and highly resistant to (MIC greater than or equal to 8 microgram/ml). The incidence of high-level resistance (1.8%) had not changed during this period. Only 8 of 17 isolates reputed to be highly clindamycin resistant that were referred to our laboratory proved to be highly resistant (MICs greater than or equal to 32 microgram/ml), whereas the other 9 were intermediately susceptible. Analysis of 2- and 10-microgram clindamycin disks for determining the susceptibility of B. fragilis revealed a high false-resistance rate with the 2-microgram disk, most errors occurring with the intermediate group. There was no false resistance with the 10-microgram disk. When disk diffusion susceptibility of B. fragilis is employed, we recommend the 10-microgram disk to predict accurately the susceptibility of B. fragilis to clindamycin.

Brain monoamine oxidase activity after in vivo-chronic iprindole treatment

The effects of chronic administration of three different doses of iprindole on the monoamine oxidase activity and neurotransmitter content were studied in the cerebral cortex, the mesencephalon and the cerebellum of mouse brain. The treatment inhibited mitochondrial monoamine oxidase activity of all three brain regions studied, although a dose-response inhibitory effect was found only in the mesencephalon. Brain regional serotonin contents were markedly increased after iprindole treatment. The 5-hydroxyindoleacetic acid contents showed a significant decrease only in the cerebral cortex. Neither dopamine nor norepinephrine brain regional contents were significantly altered. On the basis of these results it is suggested that a substrate-specific inhibition of monoamine oxidase is involved in the mechanism of action of this tricyclic antidepressant.

Glucose metabolism in the testis of the normal and streptozotocin diabetic rat

In the present work, the metabolism of [U-14C]glucose was studied in the testicular tissue of normal and streptozotocin diabetic rats. The results show that diabetes alters 14CO2 production and 14C incorporation into lipids from [U-14C]glucose. No differences were found in the [14C]proteins and [14C]nucleic acids between experimental groups. Results are discussed in relation to an insulin deficiency and/or an alteration in the hypothalamic-hypophyseal-gonadal axis.

The fine structure of the glycocalyx of equine spermatozoa: a high-resolution cytochemical study

Equine spermatozoa were obtained from ejaculates of young stallions. The seminal plasma was removed and the sperm pellets washed three times with 0-15 M-NaCl solution before final centrifugation at 4500 g for 15 min. The pellets were fixed in a mixture of 2-5% glutaraldehyde in 0-1 M-cacodylate buffer, pH 7-4, with 0-5% Alcian blue and post-fixed in 1% osmium tetroxide with 1% lanthanum nitrate; other samples were treated with ruthenium red. All samples were dehydrated in ascending concentrations of ethanol, embedded in araldite and thin sections examined in an electron microscope. Electron dense deposits of lanthanum were present on the surface plasmalemma of the head, mid-piece and tail of 70% of mature spermatozoa, and similar deposits were seen in ruthenium red-treated samples. No glycocalyx was observed in untreated spermatozoa.