Observing exocrine pancreas metabolism using a novel pancreas perfusion technique in combination with hyperpolarized [1-13 C]pyruvate

In a clinical setting, ex vivo perfusions are routinely used to maintain and assess organ viability prior to transplants. Organ perfusions are also a model system to examine metabolic flux while retaining the local physiological structure, with significant success using hyperpolarized (HP) 13 C NMR in this context. We use a novel exocrine pancreas perfusion technique via the common bile duct to assess acinar cell metabolism with HP [1-13 C]pyruvate. The exocrine component of the pancreas produces digestive enzymes through the ductal system and is often neglected in research on the pancreas. Real-time production of [1-13 C]lactate, [1-13 C]alanine, [1-13 C]malate, [4-13 C]malate, [1-13 C]aspartate, and H13 CO3 - was detected. The appearance of these resonances indicates flux through both pyruvate dehydrogenase and pyruvate carboxylase. We studied excised pancreata from C57BL/6J mice and NOD.Rag1-/- .AI4α/β mice, a commonly used model of Type 1 Diabetes (T1D). Pancreata from the T1D mice displayed increased lactate to alanine ratio without changes in oxygen consumption, signifying increased cytosolic NADH levels. The mass isotopologue analysis of the extracted pancreas tissue using gas chromatography-mass spectrometry revealed confirmatory 13 C enrichment in multiple TCA cycle metabolites that are products of pyruvate carboxylation. The methodology presented here has the potential to provide insight into mechanisms underlying several pancreatic diseases, such as diabetes, pancreatitis, and pancreatic cancer.

In vivo characterization of glutamine metabolism identifies therapeutic targets in clear cell renal cell carcinoma

Targeting metabolic vulnerabilities has been proposed as a therapeutic strategy in renal cell carcinoma (RCC). Here, we analyzed the metabolism of patient-derived xenografts (tumorgrafts) from diverse subtypes of RCC. Tumorgrafts from VHL-mutant clear cell RCC (ccRCC) retained metabolic features of human ccRCC and engaged in oxidative and reductive glutamine metabolism. Genetic silencing of isocitrate dehydrogenase-1 or isocitrate dehydrogenase-2 impaired reductive labeling of tricarboxylic acid (TCA) cycle intermediates in vivo and suppressed growth of tumors generated from tumorgraft-derived cells. Glutaminase inhibition reduced the contribution of glutamine to the TCA cycle and resulted in modest suppression of tumorgraft growth. Infusions with [amide-15N]glutamine revealed persistent amidotransferase activity during glutaminase inhibition, and blocking these activities with the amidotransferase inhibitor JHU-083 also reduced tumor growth in both immunocompromised and immunocompetent mice. We conclude that ccRCC tumorgrafts catabolize glutamine via multiple pathways, perhaps explaining why it has been challenging to achieve therapeutic responses in patients by inhibiting glutaminase.

Metabolic signatures associated with oncolytic myxoma viral infections

Oncolytic viral therapy is a recent advance in cancer treatment, demonstrating promise as a primary treatment option. To date, the secondary metabolic effects of viral infection in cancer cells has not been extensively studied. In this work, we have analyzed early-stage metabolic changes in cancer cells associated with oncolytic myxoma virus infection. Using GC–MS based metabolomics, we characterized the myxoma virus infection induced metabolic changes in three cancer cell lines—small cell (H446) and non-small cell (A549) lung cancers, and glioblastoma (SFxL). We show that even at an early stage (6 and 12 h) myxoma infection causes profound changes in cancer cell metabolism spanning several important pathways such as the citric acid cycle, fatty acid metabolism, and amino acid metabolism. In general, the metabolic effects of viral infection across cell lines are not conserved. However, we have identified several candidate metabolites that can potentially serve as biomarkers for monitoring oncolytic viral action in general.

Ex Vivo Hepatic Perfusion Through the Portal Vein in Mouse

Metabolic diseases such as diabetes, pre-diabetes, non-alcoholic fatty liver disease (NAFLD), and nonalcoholic steatohepatitis (NASH) are becoming increasingly common. Ex vivo liver perfusions allow for a comprehensive analysis of liver metabolism using nuclear magnetic resonance (NMR), in nutritional conditions that can be rigorously controlled. As in silico simulations remain a primarily theoretical means of assessing hormone actions and the effects of pharmaceutical intervention, the perfused liver remains one of the most valuable test beds for understanding hepatic metabolism. As these studies guide basic insights into hepatic physiology, results must be accurate and reproducible. The greatest factor in the reproducibility of ex vivo hepatic perfusion is the quality of surgery. Therefore, we have introduced an organized and streamlined method to perform ex vivo mouse liver perfusions in the context of in situ NMR experiments. We also describe a unique application and discuss common issues encountered in these studies. The overall purpose is to provide an uncomplicated guide to a technique we have refined over several years that we deem the golden standard for obtaining reproducible results in hepatic resections and perfusions in the context of in situ NMR experiments. The distance to the center of the field for the magnet as well as the inaccessibility of the tissue to intervention during the NMR experiment makes our methods novel.

Detecting de novo Hepatic Ketogenesis Using Hyperpolarized [2-13C] Pyruvate

The role of ketones in metabolic health has progressed over the past two decades, moving from what was perceived as a simple byproduct of fatty acid oxidation to a central player in a multiplicity of disease states. Previous work with hyperpolarized (HP) ¹³C has shown that ketone production can be detected when using precursors that labeled acetyl-CoA at the C1 position, often in tissues that are not normally recognized as ketogenic. Here, we assay metabolism of HP [2-¹³C]pyruvate in the perfused mouse liver, a classic metabolic testbed where nutritional conditions can be precisely controlled. Livers perfused with long-chain fatty acids or the medium-chain fatty acid octanoate showed no evidence of ketogenesis in the ¹³C spectrum. In contrast, addition of dichloroacetate, a potent inhibitor of pyruvate dehydrogenase kinase, resulted in significant production of both acetoacetate and 3-hydroxybutyrate from the pyruvate precursor. This result indicates that ketones are readily produced from carbohydrates, but only in the case where pyruvate dehydrogenase activity is upregulated.

INCA 2.0: A tool for integrated, dynamic modeling of NMR- and MS-based isotopomer measurements and rigorous metabolic flux analysis

Metabolic flux analysis (MFA) combines experimental measurements and computational modeling to determine biochemical reaction rates in live biological systems. Advancements in analytical instrumentation, such as nuclear magnetic resonance (NMR) spectroscopy and mass spectrometry (MS), have facilitated chemical separation and quantification of isotopically enriched metabolites. However, no software packages have been previously described that can integrate isotopomer measurements from both MS and NMR analytical platforms and have the flexibility to estimate metabolic fluxes from either isotopic steady-state or dynamic labeling experiments. By applying physiologically relevant cardiac and hepatic metabolic models to assess NMR isotopomer measurements, we herein test and validate new modeling capabilities of our enhanced flux analysis software tool, INCA 2.0. We demonstrate that INCA 2.0 can simulate and regress steady-state ¹³C NMR datasets from perfused hearts with an accuracy comparable to other established flux assessment tools. Furthermore, by simulating the infusion of three different ¹³C acetate tracers, we show that MFA based on dynamic ¹³C NMR measurements can more precisely resolve cardiac fluxes compared to isotopically steady-state flux analysis. Finally, we show that estimation of hepatic fluxes using combined ¹³C NMR and MS datasets improves the precision of estimated fluxes by up to 50%. Overall, our results illustrate how the recently added NMR data modeling capabilities of INCA 2.0 can enable entirely new experimental designs that lead to improved flux resolution and can be applied to a wide range of biological systems and measurement time courses.

Comparison of selective excitation and multi-echo chemical shift encoding for imaging of hyperpolarized [1-13C]pyruvate

Imaging methods for hyperpolarized (HP) ¹³C agents must sample the evolution of signal from multiple agents with distinct chemical shifts within a very brief timeframe (typically < 1 min), which is challenging using conventional imaging methods. In this work, we compare two of the most commonly used HP spectroscopic imaging methods, spectral-spatial selective excitation and multi-echo chemical shift encoding (CSE, also referred to as IDEAL), for a typical preclinical HP [1-¹³C]pyruvate imaging scan at 7 T. Both spectroscopic encoding techniques were implemented and validated in HP experiments imaging enzyme phantoms and the murine kidney. SNR performance of these two spectroscopic imaging approaches was compared in numerical simulations and phantom experiments using a single-shot flyback EPI readout for spatial encoding. With identical effective excitation angles, the SNR of images acquired with spectral-spatial excitations and CSE were found to be effectively equivalent.

Insulin resistance is mechanistically linked to hepatic mitochondrial remodeling in non-alcoholic fatty liver disease

OBJECTIVE

Insulin resistance and altered hepatic mitochondrial function are central features of type 2 diabetes (T2D) and non-alcoholic fatty liver disease (NAFLD), but the etiological role of these processes in disease progression remains unclear. Here we investigated the molecular links between insulin resistance, mitochondrial remodeling, and hepatic lipid accumulation.

METHODS

Hepatic insulin sensitivity, endogenous glucose production, and mitochondrial metabolic fluxes were determined in wild-type, obese (ob/ob) and pioglitazone-treatment obese mice using a combination of radiolabeled tracer and stable isotope NMR approaches. Mechanistic studies of pioglitazone action were performed in isolated primary hepatocytes, whilst molecular hepatic lipid species were profiled using shotgun lipidomics.

RESULTS

Livers from obese, insulin-resistant mice displayed augmented mitochondrial content and increased tricarboxylic acid cycle (TCA) cycle and pyruvate dehydrogenase (PDH) activities. Insulin sensitization with pioglitazone mitigated pyruvate-driven TCA cycle activity and PDH activation via both allosteric (intracellular pyruvate availability) and covalent (PDK4 and PDP2) mechanisms that were dependent on PPARγ activity in isolated primary hepatocytes. Improved mitochondrial function following pioglitazone treatment was entirely dissociated from changes in hepatic triglycerides, diacylglycerides, or fatty acids. Instead, we highlight a role for the mitochondrial phospholipid cardiolipin, which underwent pathological remodeling in livers from obese mice that was reversed by insulin sensitization.

CONCLUSION

Our findings identify targetable mitochondrial features of T2D and NAFLD and highlight the benefit of insulin sensitization in managing the clinical burden of obesity-associated disease.

Deuterated water imaging of the rat brain following metabolism of [2 H7 ]glucose

PURPOSE

To determine whether deuterated water (HDO) generated from the metabolism of [² H₇ ]glucose is a sensitive biomarker of cerebral glycolysis and oxidative flux.

METHODS

A bolus of [² H₇ ]glucose was injected through the tail vein at 1.95 g/kg into Sprague-Dawley rats. A ² H surface coil was placed on top of the head to record ² H spectra of the brain every 1.3 minutes to measure glucose uptake and metabolism to HDO, lactate, and glutamate/glutamine. A two-point Dixon method based on a gradient-echo sequence was used to reconstruct deuterated glucose and water (HDO) images selectively.

RESULTS

The background HDO signal could be detected and imaged before glucose injection. The ² H NMR spectra showed arrival of [² H₇ ]glucose and its metabolism in a time-dependent manner. A ratio of the HDO to glutamate/glutamine resonances demonstrates a pseudo-steady state following injection, in which cerebral metabolism dominates wash-in of HDO generated by peripheral metabolism. Brain spectroscopy reveals that HDO generation is linear with lactate and glutamate/glutamine appearance in the appropriate pseudo-steady state window. Selective imaging of HDO and glucose is easily accomplished using a gradient-echo method.

CONCLUSION

Metabolic imaging of HDO, as a marker of glucose, lactate, and glutamate/glutamine metabolism, has been shown here for the first time. Cerebral glucose metabolism can be assessed efficiently using a standard gradient-echo sequence that provides superior in-plane resolution compared with CSI-based techniques.

Application of Carbon-13 Isotopomer Analysis to Assess Perinatal Myocardial Glucose Metabolism in Sheep

Ovine models of pregnancy have been used extensively to study maternal-fetal interactions and have provided considerable insight into nutrient transfer to the fetus. Ovine models have also been utilized to study congenital heart diseases. In this work, we demonstrate a comprehensive assessment of heart function and metabolism using a perinatal model of heart function with the addition of a [U-¹³C]glucose as tracer to study central energy metabolism. Using nuclear magnetic resonance spectroscopy, and metabolic modelling, we estimate myocardial citric acid cycle turnover (normalized for oxygen consumption), substrate selection, and anaplerotic fluxes. This methodology can be applied to studying acute and chronic effects of hormonal signaling in future studies.

Kinetic Analysis of Hepatic Metabolism Using Hyperpolarized Dihydroxyacetone

Hyperpolarized carbon-13 magnetic resonance (HP-MR) is a new metabolic imaging method the does not use ionizing radiation. Due to the inherent chemical specificity of MR, not only tracer uptake but also downstream metabolism of the agent is detected in a straightforward manner. HP [2-¹³C] dihydroxyacetone (DHA) is a promising new agent that directly interrogates hepatic glucose metabolism. DHA has three metabolic fates in the liver: glucose production, glycerol production and potential inclusion into triglycerides, and oxidation in the tricarboxylic acid cycle. Each pathway is regulated by flux through multiple enzymes. Using Duhamel's formula, the kinetics of DHA metabolism is modeled, resulting in estimates of specific reaction rate constants. The multiple enzymatic steps that control DHA metabolism make more simplified methods for extracting kinetic data less than satisfactory. The described modeling paradigm effectively identifies changes in metabolism between gluconeogenic and glycogenolytic models of hepatic function.

Real-Time Analysis of Folding upon Binding of a Disordered Protein by Using Dissolution DNP NMR Spectroscopy

The kinase inhibitory domain of the cell cycle regulatory protein p27^Kip1 (p27) was nuclear spin hyperpolarized using dissolution dynamic nuclear polarization (D-DNP). While intrinsically disordered in isolation, p27 adopts secondary structural motifs, including an α-helical structure, upon binding to cyclin-dependent kinase 2 (Cdk2)/cyclin A. The sensitivity gains obtained with hyperpolarization enable the real-time observation of ¹³ C NMR signals during p27 folding upon binding to Cdk2/cyclin A on a time scale of several seconds. Time-dependent intensity changes are dependent on the extent of folding and binding, as manifested in differential spin relaxation. The analysis of signal decay rates suggests the existence of a partially folded p27 intermediate during the timescale of the D-DNP NMR experiment.

A comprehensive analysis of myocardial substrate preference emphasizes the need for a synchronized fluxomic/metabolomic research design

The heart oxidizes fatty acids, carbohydrates, and ketone bodies inside the tricarboxylic acid (TCA) cycle to generate the reducing equivalents needed for ATP production. Competition between these substrates makes it difficult to estimate the extent of pyruvate oxidation. Previously, hyperpolarized pyruvate detected propionate-mediated activation of carbohydrate oxidation, even in the presence of acetate. In this report, the optimal concentration of propionate for the activation of glucose oxidation was measured in mouse hearts perfused in Langendorff mode. This study was performed with a more physiologically relevant perfusate than the previous work. Increasing concentrations of propionate did not cause adverse effects on myocardial metabolism, as evidenced by unchanged O₂ consumption, TCA cycle flux, and developed pressures. Propionate at 1 mM was sufficient to achieve significant increases in pyruvate dehydrogenase flux (3×), and anaplerosis (6×), as measured by isotopomer analysis. These results further demonstrate the potential of propionate as an aid for the correct estimation of total carbohydrate oxidative capacity in the heart. However, liquid chromotography/mass spectroscopy-based metabolomics detected large changes (~30-fold) in malate and fumarate pool sizes. This observation leads to a key observation regarding mass balance in the TCA cycle; flux through a portion of the cycle can be drastically elevated without changing the O₂ consumption.

Site specific polarization transfer from a hyperpolarized ligand of dihydrofolate reductase

Protein-ligand interaction is often characterized using polarization transfer by the intermolecular nuclear Overhauser effect (NOE). For such NOE experiments, hyperpolarization of nuclear spins presents the opportunity to increase the spin magnetization, which is transferred, by several orders of magnitude. Here, folic acid, a ligand of dihydrofolate reductase (DHFR), was hyperpolarized on (1)H spins using dissolution dynamic nuclear polarization (D-DNP). Mixing hyperpolarized ligand with protein resulted in observable increases in protein (1)H signal predominantly in the methyl group region of the spectra. Using (13)C single quantum selection in a series of one-dimensional spectra, the carbon chemical shift ranges of the corresponding methyl groups can be elucidated. Signals observed in these hyperpolarized spectra could be confirmed using 3D isotope filtered NOESY spectra, although the hyperpolarized spectra were obtained in single scans. By further correlating the signal intensities observed in the D-DNP experiments with the occurrence of short distances in the crystal structure of the protein-ligand complex, the observed methyl proton signals could be matched to the chemical shifts of six amino acids in the active site of DHFR-folic acid binary complex. These data demonstrate that (13)C chemical shift selection of protein resonances, combined with the intrinsic selectivity towards magnetization originating from the initially hyperpolarized spins, can be used for site specific characterization of protein-ligand interactions.

Application of blind source separation to real-time dissolution dynamic nuclear polarization

The use of a blind source separation (BSS) algorithm is demonstrated for the analysis of time series of nuclear magnetic resonance (NMR) spectra. This type of data is obtained commonly from experiments, where analytes are hyperpolarized using dissolution dynamic nuclear polarization (D-DNP), both in in vivo and in vitro contexts. High signal gains in D-DNP enable rapid measurement of data sets characterizing the time evolution of chemical or metabolic processes. BSS is based on an algorithm that can be applied to separate the different components contributing to the NMR signal and determine the time dependence of the signals from these components. This algorithm requires minimal prior knowledge of the data, notably, no reference spectra need to be provided, and can therefore be applied rapidly. In a time-resolved measurement of the enzymatic conversion of hyperpolarized oxaloacetate to malate, the two signal components are separated into computed source spectra that closely resemble the spectra of the individual compounds. An improvement in the signal-to-noise ratio of the computed source spectra is found compared to the original spectra, presumably resulting from the presence of each signal more than once in the time series. The reconstruction of the original spectra yields the time evolution of the contributions from the two sources, which also corresponds closely to the time evolution of integrated signal intensities from the original spectra. BSS may therefore be an approach for the efficient identification of components and estimation of kinetics in D-DNP experiments, which can be applied at a high level of automation.

Posttraumatic Intrahepatic Bilioma

Blunt injury abdomen causing biliary injury is rare in children. Collection of bile within or outside the liver after biliary injury is called bilioma. CT scan images of late presenting intra-hepatic bilioma are shown.

Segmental dilatation of near total colon managed by colon preserving surgery

Segmental dilatation of the colon is a rare congenital disorder of colonic motility and often involves a short segment that causes chronic constipation in children. There are only 10 cases of neonatal colonic segmental dilatation described in literature. We managed a case who presented in the neonatal period with abdominal distension. There was dilatation of whole of the colon except part of ascending colon and the rectum. The case was managed by tubularization of the segmental dilatation of colon with stoma formation as first stage followed by delayed anastomosis during second stage.

Exstrophy bladder: Effect of sigmoid colocystoplasty on physical growth and bone mineral density

Background and Aims:

Introduction of intestinal tissue in the urinary tract results in numerous metabolic changes. This study investigates the effects of augmentation sigmoid colocystoplasty on the physical growth and bone mineralization in bladder exstrophy patients.

Materials and Methods:

Physical growth, serum biochemistry and bone mineral density were assessed pre and post augmentation in 34 of 54 patients who were treated by staged sigmoid colocystoplasty for classical bladder exstrophy during the period 1985–2007. Physical growth was determined by comparing the height and weight for age with standard growth charts. Serum biochemistry included calcium, phosphate and alkaline phosphatase levels. Bone mineral density (BMD) was determined at the femoral head using the dual energy X-ray absorptiometry (DEXA) scan at 15 ± 4.5 months after the augmentation. The DEXA scan findings were compared with 22 normal Indian children who served as controls and 18 unaugmented patients with bladder exstrophy. In 13 augmented patients, the DEXA scan could be repeated after an interval of six months.

Results:

The mean percentile height and weight were comparable in the pre and post-augmentation period with no statistically significant difference (P=0.135 for height and P=0.232 for weight). Biochemical parameters of bone metabolism also did not show any statistically significant changes after colocystoplasty. The BMD was 0.665 ± 0.062 g/cm² in the controls and 0.612 ± 0.10 g/cm² in the unaugmented bladder exstrophy patients. In the augmented patients, the BMD was 0.645 ± 0.175 g/cm² and six months later it was 0.657 ± 0.158 g/cm². These differences were not statistically significant.

Conclusions:

In our study, no significant effects on the physical growth and bone mineral metabolism were observed in exstrophy bladder patients following sigmoid colocystoplasty.

Solution NMR of polypeptides hyperpolarized by dynamic nuclear polarization

Hyperpolarization of nuclear spins through techniques such as dynamic nuclear polarization (DNP) can greatly increase the signal-to-noise ratio in NMR measurements, thus eliminating the need for signal averaging. This enables the study of many dynamic processes which would otherwise not be amenable to study by NMR spectroscopy. A report of solid- to liquid-state DNP of a short peptide, bacitracin A, as well as of a full-length protein, L23, is presented here. The polypeptides are hyperpolarized at low temperature and dissolved for NMR signal acquisition in the liquid state in mixtures of organic solvent and water. Signal enhancements of 300-2000 are obtained in partially deuterated polypeptide when hyperpolarized on (13)C and of 30-180 when hyperpolarized on (1)H. A simulated spectrum is used to identify different resonances in the hyperpolarized (13)C spectra, and the relation between observed signal enhancement for various groups in the protein and relaxation parameters measured from the hyperpolarized samples is discussed. Thus far, solid- to liquid-state DNP has been used in conjunction with small molecules. The results presented here, however, demonstrate the feasibility of hyperpolarizing larger proteins, with potential applications toward the study of protein folding or macromolecular interactions.

Peripherally inserted central venous lines versus central lines in surgical newborns--a comparison

OBJECTIVE

To compare the insertion characteristics, utilization profile, life span and the complication rates of Central lines (CL) and Peripherally inserted central lines (PICL).

METHODS

A prospective study of all CL or PICL insertions during January 2007 to September 2007 in the Neonatal Surgical Intensive Care Unit of a tertiary care center was done. The number of attempts, procedure time, duration of catheter stay, number of dressing done, complication during insertion and maintenance and cause of removal were noted and the differences analyzed statistically using Pearson chi square / t test. P value. 0.05 was considered significant.

RESULTS

Ninety two neonates were included in the present study of whom 60 were PICL insertions and 32 CL insertions. The two groups were comparable in terms of age, weight and the use of total perental nutrition (TPN) through the catheters. On comparing the PICL and CL groups, the number of attempts for successful insertion (p=0.003), the time taken (p=0.005), the number of dressing changes required during the indwelling period (p=0.005) and the overall complication rates (p=0.002) were significantly less in the PICL group. The PICL could be maintained for longer periods of time (p= 0.005) and only in 11.5% of the patients it had to be removed before completion of therapy as compared to 37.5% early removals for CL (p=0.02)

CONCLUSION

PICL is a safe, effective and reliable method of providing prolonged IV access in newborns. It also has the least incidence of complications during insertion and maintenance over prolonged period of time when compared to CL and should be recommended for routine use in neonatal surgical patients.

Development of an indirect enzyme immunoassay using monoclonal antibodies for the measurement of 17alpha-hydroxyprogesterone in human serum

An indirect enzyme immunoassay for the measurement of total 17alpha-hydroxyprogesterone (17OHP) in serum using monoclonal antibodies generated in our laboratory was developed. Here, (a) instead of extraction with solvents, serum was heated to free protein-bound 17OHP and assay was performed at pH 9.6, (b) to ensure uniform assay conditions for both standards and samples, buffer for standards contained charcoal-stripped pre-heated pooled cord serum. Assays were done in 96-well EIA microplates pre-coated with 17alpha-hydroxyprogesterone-3-(o-carboxymethyl)oxime: bovine serum albumin. Secondary antibody was horseradish peroxidase-linked sheep anti-mouse IgG polyclonal antibody. The method was accurate and suitable for screening for congenital adrenal hyperplasia.

Peritoneal penetrating pencil injury

An 8 year old school going boy sustained an accidental peritoneal penetrating injury while playing with a pencil in his trouser pocket. Surgical exploration revealed intact intraperitoneal and retroperitoneal viscera and the pencil could be successfully removed. In addition to the acute injuries there are numerous late sequlae of pencil injuries that cause concern.

Production and Characterization of Monoclonal Antibodies Against 17α-Hydroxyprogesterone

Hybridomas secreting monoclonal antibodies (MAbs) against 17alpha-hydroxyprogesterone (17OHP) have been generated. These MAbs are highly specific and have an affinity of 7-12 x 10(7) M(1). The hybridomas were obtained by fusion of spleen cells from immunized mice with mouse myeloma P3X63 Ag8.653 cells. The antigen used for immunization was 17OHP conjugated to bovine serum albumin (17OHP:BSA). Fused cells were plated and cloned in 96-well microtiter plates. Wells containing hybridomas were screened simultaneously for specific gamma globulin (IgG) and anti-17OHP activity using an enzyme-linked immunosorbent assay (ELISA)-based method, which is faster than the conventional radioimmunoassay (RIA) screening procedure. Limiting dilution methods were used to obtain single hybridoma clones producing MAb. The stable hybridomas secreting anti-17OHP MAbs were expanded into bioreactors or ascites fluid for large-scale production of the required antibodies. These MAbs will be used in the formulation of a 17OHP assay kit to screen for congenital adrenal hyperplasia (CAH) in local newborn human population.

The effects of oestradiol and relaxin on extensibility and collagen organisation of the pregnant rat cervix

The effects of exogenously introduced oestradiol-17 beta (E) and relaxin (RLX) on cervical extensibility and collagen organisation were tested in rats ovariectomised in late pregnancy. When the cervices were stretched in vitro by 1 mm increments, it was found that those from rats given E alone generated significantly higher tensions than those from control rats, while cervices from rats given both E and RLX had tensions similar to controls. Examination of cervical sections under the light microscope and ultra-thin sections under the electron microscope showed that the collagen fibres in the cervices from E-treated rats were highly organised, whereas those from animals given E+RLX and control animals were disorganised and dispersed. It was concluded that E decreased cervical extensibility, while RLX counteracted the effect of E to maintain a soft and easily extensible cervix.