Identification and evaluation of small-molecule inhibitors against the dNTPase SAMHD1 via a comprehensive screening funnel

SAMHD1 is a dNTP triphosphohydrolase governing nucleotide pool homeostasis and can detoxify chemotherapy metabolites controlling their clinical responses. To understand SAMHD1 biology and investigate the potential of targeting SAMHD1 as neoadjuvant to current chemotherapies, we set out to discover selective small-molecule inhibitors. Here, we report a discovery pipeline encompassing a biochemical screening campaign and a set of complementary biochemical, biophysical, and cell-based readouts for rigorous characterization of the screen output. The identified small molecules, TH6342 and analogs, accompanied by inactive control TH7126, demonstrated specific, low μM potency against both physiological and oncology-drug-derived substrates. By coupling kinetic studies with thermal shift assays, we reveal the inhibitory mechanism of TH6342 and analogs, which engage pre-tetrameric SAMHD1 and deter oligomerization and allosteric activation without occupying nucleotide-binding pockets. Altogether, our study diversifies inhibitory modes against SAMHD1, and the discovery pipeline reported herein represents a thorough framework for future SAMHD1 inhibitor development.

The value of "diaphragmatic relaxing incision" for the durability of the crural repair in patients with paraesophageal hernia: a double blind randomized clinical trial

Background

Surgical repair of paraesophageal hernias (PEHs) is burdened with high recurrence rates, and hitherto various techniques explored to enforce the traditional crural repair have not been successful. The hiatal reconstruction in PEH is exposed to significant tension, which may be minimized by adding a diaphragmatic relaxing incision to enhance the durability of the crural repair.

Patients and methods

All individuals undergoing elective laparoscopic repair of a large PEH, irrespective of age, were considered eligible. PEHs were classified into types II-IV. The preoperative work-up program included multidetector computed tomography and symptom assessment questionnaires, which will be repeated during the postoperative follow-up. Patients were randomly divided into a control group with crural repair alone and an intervention group with the addition of a left-sided diaphragmatic relaxing incision at the edge of the upper pole of the spleen. The diaphragmatic defect was then covered by a synthetic mesh.

Results

The primary endpoint of this trial was the rate of anatomical PEH recurrence at 1 year. Secondary endpoints included symptomatic gastroesophageal reflux disease, dysphagia, odynophagia, gas bloat, regurgitation, chest pain, abdominal pain, nausea, vomiting, postprandial pain, cardiovascular and pulmonary symptoms, and patient satisfaction in the immediate postoperative course (3 months) and at 1 year. Postoperative complications, morbidity, and disease burden were recorded for each patient. This was a double-blind study, meaning that the operation report was filed in a locked archive to keep the patient, staff, and clinical assessors blinded to the study group allocation. Blinding must not be broken during the follow-up unless required by any emergencies in the clinical management of the patient. Likewise, the patients must not be informed about the details of the operation.

Trial Registration

ClinicalTrials.gov, identification number NCT04179578.

A FabG inhibitor targeting an allosteric binding site inhibits several orthologs from Gram-negative ESKAPE pathogens

The spread of antibiotic resistance within the ESKAPE group of human pathogenic bacteria poses severe challenges in the treatment of infections and maintenance of safe hospital environments. This motivates efforts to validate novel target proteins within these species that could be pursued as potential targets for antibiotic development. Genetic data suggest that the enzyme FabG, which is part of the bacterial fatty acid biosynthetic system FAS-II, is essential in several ESKAPE pathogens. FabG catalyzes the NADPH dependent reduction of 3-keto-acyl-ACP during fatty acid elongation, thus enabling lipid supply for production and maintenance of the cell envelope. Here we report on small-molecule screening on the FabG enzymes from A. baumannii and S. typhimurium to identify a set of µM inhibitors, with the most potent representative (1) demonstrating activity against six FabG-orthologues. A co-crystal structure with FabG from A. baumannii (PDB:6T65) confirms inhibitor binding at an allosteric site located in the subunit interface, as previously demonstrated for other sub-µM inhibitors of FabG from P. aeruginosa. We show that inhibitor binding distorts the oligomerization interface in the FabG tetramer and displaces crucial residues involved in the interaction with the co-substrate NADPH. These observations suggest a conserved allosteric site across the FabG family, which can be potentially targeted for interference with fatty acid biosynthesis in clinically relevant ESKAPE pathogens.

Ribonucleotide reductase inhibitors suppress SAMHD1 ara-CTPase activity enhancing cytarabine efficacy

The deoxycytidine analogue cytarabine (ara-C) remains the backbone treatment of acute myeloid leukaemia (AML) as well as other haematological and lymphoid malignancies, but must be combined with other chemotherapeutics to achieve cure. Yet, the underlying mechanism dictating synergistic efficacy of combination chemotherapy remains largely unknown. The dNTPase SAMHD1, which regulates dNTP homoeostasis antagonistically to ribonucleotide reductase (RNR), limits ara-C efficacy by hydrolysing the active triphosphate metabolite ara-CTP. Here, we report that clinically used inhibitors of RNR, such as gemcitabine and hydroxyurea, overcome the SAMHD1-mediated barrier to ara-C efficacy in primary blasts and mouse models of AML, displaying SAMHD1-dependent synergy with ara-C. We present evidence that this is mediated by dNTP pool imbalances leading to allosteric reduction of SAMHD1 ara-CTPase activity. Thus, SAMHD1 constitutes a novel biomarker for combination therapies of ara-C and RNR inhibitors with immediate consequences for clinical practice to improve treatment of AML.

Perspective on CETSA Literature: Toward More Quantitative Data Interpretation

The cellular thermal shift assay (CETSA) was introduced in 2013 to investigate drug-target engagement inside live cells and tissues. As with all thermal shift assays, the response measured by CETSA is not simply governed by ligand affinity to the investigated target protein, but the thermodynamics and kinetics of ligand binding and protein unfolding also contribute to the observed protein stabilization. This limitation is commonly neglected in current applications of the method to validate the target of small-molecule probes. Instead, there is an eagerness to make direct comparisons of CETSA measurements with functional and phenotypic readouts from cells at 37 °C. Here, we present a perspective of the early CETSA literature and put the accumulated data into a quantitative context. The analysis includes annotation of ~270 peer-reviewed papers, the majority of which do not consider the underlying biophysical basis of CETSA. We also detail what future technology developments are needed to enable CETSA-based optimization of structure-activity relationships and more appropriate comparisons of these data with functional or phenotypic responses. Finally, we describe ongoing developments in assay formats that allow for CETSA measurements at single-cell resolution, with the aspiration to allow differentiation in cellular target engagement between cells in co-cultures and more complex models, such as organoids and potentially even tissue.

Using High Content Imaging to Quantify Target Engagement in Adherent Cells

Quantitating the interaction of small molecules with their intended protein target is critical for drug development, target validation and chemical probe validation. Methods that measure this phenomenon without modification of the protein target or small molecule are particularly valuable though technically challenging. The cellular thermal shift assay (CETSA) is one technique to monitor target engagement in living cells. Here, we describe an adaptation of the original CETSA protocol, which allows for high throughput measurements while retaining subcellular localization at the single cell level. We believe this protocol offers important advances to the application of CETSA for in-depth characterization of compound-target interaction, especially in heterogeneous populations of cells.

Using High Content Imaging to Quantify Target Engagement in Adherent Cells

Quantitating the interaction of small molecules with their intended protein target is critical for drug development, target validation and chemical probe validation. Methods that measure this phenomenon without modification of the protein target or small molecule are particularly valuable though technically challenging. The cellular thermal shift assay (CETSA) is one technique to monitor target engagement in living cells. Here, we describe an adaptation of the original CETSA protocol, which allows for high throughput measurements while retaining subcellular localization at the single cell level. We believe this protocol offers important advances to the application of CETSA for in-depth characterization of compound-target interaction, especially in heterogeneous populations of cells.

Quantitative Interpretation of Intracellular Drug Binding and Kinetics Using the Cellular Thermal Shift Assay

Evidence of physical interaction with the target protein is essential in the development of chemical probes and drugs. The cellular thermal shift assay (CETSA) allows evaluation of drug binding in live cells but lacks a framework to support quantitative interpretations and comparisons with functional data. We outline an experimental platform for such analysis using human kinase p38α. Systematic variations to the assay's characteristic heat challenge demonstrate an apparent loss of compound potency with an increase in duration or temperature, in line with expectations from the literature for thermal shift assays. Importantly, data for five structurally diverse inhibitors can be quantitatively explained using a simple model of linked equilibria and published binding parameters. The platform further distinguishes between ligand mechanisms and allows for quantitative comparisons of drug binding affinities and kinetics in live cells and lysates. We believe this work has broad implications in the appropriate use of the CETSA for target and compound validation.

In Situ Target Engagement Studies in Adherent Cells

A prerequisite for successful drugs is effective binding of the desired target protein in the complex environment of a living system. Drug-target engagement has typically been difficult to monitor in physiologically relevant models, and with current methods, especially, while maintaining spatial information. One recent technique for quantifying drug-target engagement is the cellular thermal shift assay (CETSA), in which ligand-induced protein stabilization is measured after a heat challenge. Here, we describe a CETSA protocol in live A431 cells for p38α (MAPK14), where remaining soluble protein is detected in situ, using high-content imaging in 384-well, microtiter plates. We validate this assay concept using a number of known p38α inhibitors and further demonstrate the potential of this technology for chemical probe and drug discovery purposes by performing a small pilot screen for novel p38α binders. Importantly, this protocol creates a workflow that is amenable to adherent cells in their native state and yields spatially resolved target engagement information measurable at the single-cell level.

Targeting SAMHD1 with the Vpx protein to improve cytarabine therapy for hematological malignancies

The cytostatic deoxycytidine analog cytarabine (ara-C) is the most active agent available against acute myelogenous leukemia (AML). Together with anthracyclines, ara-C forms the backbone of AML treatment for children and adults. In AML, both the cytotoxicity of ara-C in vitro and the clinical response to ara-C therapy are correlated with the ability of AML blasts to accumulate the active metabolite ara-C triphosphate (ara-CTP), which causes DNA damage through perturbation of DNA synthesis. Differences in expression levels of known transporters or metabolic enzymes relevant to ara-C only partially account for patient-specific differential ara-CTP accumulation in AML blasts and response to ara-C treatment. Here we demonstrate that the deoxynucleoside triphosphate (dNTP) triphosphohydrolase SAM domain and HD domain 1 (SAMHD1) promotes the detoxification of intracellular ara-CTP pools. Recombinant SAMHD1 exhibited ara-CTPase activity in vitro, and cells in which SAMHD1 expression was transiently reduced by treatment with the simian immunodeficiency virus (SIV) protein Vpx were dramatically more sensitive to ara-C-induced cytotoxicity. CRISPR-Cas9-mediated disruption of the gene encoding SAMHD1 sensitized cells to ara-C, and this sensitivity could be abrogated by ectopic expression of wild-type (WT), but not dNTPase-deficient, SAMHD1. Mouse models of AML lacking SAMHD1 were hypersensitive to ara-C, and treatment ex vivo with Vpx sensitized primary patient-derived AML blasts to ara-C. Finally, we identified SAMHD1 as a risk factor in cohorts of both pediatric and adult patients with de novo AML who received ara-C treatment. Thus, SAMHD1 expression levels dictate patient sensitivity to ara-C, providing proof-of-concept that the targeting of SAMHD1 by Vpx could be an attractive therapeutic strategy for potentiating ara-C efficacy in hematological malignancies.

Identification of Drug-Like Inhibitors of Insulin-Regulated Aminopeptidase Through Small-Molecule Screening

Intracerebroventricular injection of angiotensin IV, a ligand of insulin-regulated aminopeptidase (IRAP), has been shown to improve cognitive functions in several animal models. Consequently, IRAP is considered a potential target for treatment of cognitive disorders. To identify nonpeptidic IRAP inhibitors, we adapted an established enzymatic assay based on membrane preparations from Chinese hamster ovary cells and a synthetic peptide-like substrate for high-throughput screening purposes. The 384-well microplate-based absorbance assay was used to screen a diverse set of 10,500 compounds for their inhibitory capacity of IRAP. The assay performance was robust with Z'-values ranging from 0.81 to 0.91, and the screen resulted in 23 compounds that displayed greater than 60% inhibition at a compound concentration of 10 μM. After hit confirmation experiments, purity analysis, and promiscuity investigations, three structurally different compounds were considered particularly interesting as starting points for the development of small-molecule-based IRAP inhibitors. After resynthesis, all three compounds confirmed low μM activity and were shown to be rapidly reversible. Additional characterization included activity in a fluorescence-based orthogonal assay and in the presence of a nonionic detergent and a reducing agent, respectively. Importantly, the characterized compounds also showed inhibition of the human ortholog, prompting our further interest in these novel IRAP inhibitors.

CETSA screening identifies known and novel thymidylate synthase inhibitors and slow intracellular activation of 5-fluorouracil

Target engagement is a critical factor for therapeutic efficacy. Assessment of compound binding to native target proteins in live cells is therefore highly desirable in all stages of drug discovery. We report here the first compound library screen based on biophysical measurements of intracellular target binding, exemplified by human thymidylate synthase (TS). The screen selected accurately for all the tested known drugs acting on TS. We also identified TS inhibitors with novel chemistry and marketed drugs that were not previously known to target TS, including the DNA methyltransferase inhibitor decitabine. By following the cellular uptake and enzymatic conversion of known drugs we correlated the appearance of active metabolites over time with intracellular target engagement. These data distinguished a much slower activation of 5-fluorouracil when compared with nucleoside-based drugs. The approach establishes efficient means to associate drug uptake and activation with target binding during drug discovery.

Crystal structures of the kinase domain of the sulfate-activating complex in Mycobacterium tuberculosis

In Mycobacterium tuberculosis the sulfate activating complex provides a key branching point in sulfate assimilation. The complex consists of two polypeptide chains, CysD and CysN. CysD is an ATP sulfurylase that, with the energy provided by the GTPase activity of CysN, forms adenosine-5’-phosphosulfate (APS) which can then enter the reductive branch of sulfate assimilation leading to the biosynthesis of cysteine. The CysN polypeptide chain also contains an APS kinase domain (CysC) that phosphorylates APS leading to 3’-phosphoadenosine-5’-phosphosulfate, the sulfate donor in the synthesis of sulfolipids. We have determined the crystal structures of CysC from M. tuberculosis as a binary complex with ADP, and as ternary complexes with ADP and APS and the ATP mimic AMP-PNP and APS, respectively, to resolutions of 1.5 Å, 2.1 Å and 1.7 Å, respectively. CysC shows the typical APS kinase fold, and the structures provide comprehensive views of the catalytic machinery, conserved in this enzyme family. Comparison to the structure of the human homolog show highly conserved APS and ATP binding sites, questioning the feasibility of the design of specific inhibitors of mycobacterial CysC. Residue Cys556 is part of the flexible lid region that closes off the active site upon substrate binding. Mutational analysis revealed this residue as one of the determinants controlling lid closure and hence binding of the nucleotide substrate.

Inhibition of Insulin-Regulated Aminopeptidase (IRAP) by Arylsulfonamides

The inhibition of insulin-regulated aminopeptidase (IRAP, EC 3.4.11.3) by angiotenesin IV is known to improve memory and learning in rats. Screening 10 500 low-molecular-weight compounds in an enzyme inhibition assay with IRAP from Chinese Hamster Ovary (CHO) cells provided an arylsulfonamide (N-(3-(1H-tetrazol-5-yl)phenyl)-4-bromo-5-chlorothiophene-2-sulfonamide), comprising a tetrazole in the meta position of the aromatic ring, as a hit. Analogues of this hit were synthesized, and their inhibitory capacities were determined. A small structure-activity relationship study revealed that the sulfonamide function and the tetrazole ring are crucial for IRAP inhibition. The inhibitors exhibited a moderate inhibitory potency with an IC50=1.1±0.5 μm for the best inhibitor in the series. Further optimization of this new class of IRAP inhibitors is required to make them attractive as research tools and as potential cognitive enhancers.

The cellular thermal shift assay for evaluating drug target interactions in cells

Thermal shift assays are used to study thermal stabilization of proteins upon ligand binding. Such assays have been used extensively on purified proteins in the drug discovery industry and in academia to detect interactions. Recently, we published a proof-of-principle study describing the implementation of thermal shift assays in a cellular format, which we call the cellular thermal shift assay (CETSA). The method allows studies of target engagement of drug candidates in a cellular context, herein exemplified with experimental data on the human kinases p38α and ERK1/2. The assay involves treatment of cells with a compound of interest, heating to denature and precipitate proteins, cell lysis, and the separation of cell debris and aggregates from the soluble protein fraction. Whereas unbound proteins denature and precipitate at elevated temperatures, ligand-bound proteins remain in solution. We describe two procedures for detecting the stabilized protein in the soluble fraction of the samples. One approach involves sample workup and detection using quantitative western blotting, whereas the second is performed directly in solution and relies on the induced proximity of two target-directed antibodies upon binding to soluble protein. The latter protocol has been optimized to allow an increased throughput, as potential applications require large numbers of samples. Both approaches can be completed in a day.

MTH1 inhibition eradicates cancer by preventing sanitation of the dNTP pool

Cancers have dysfunctional redox regulation resulting in reactive oxygen species production, damaging both DNA and free dNTPs. The MTH1 protein sanitizes oxidized dNTP pools to prevent incorporation of damaged bases during DNA replication. Although MTH1 is non-essential in normal cells, we show that cancer cells require MTH1 activity to avoid incorporation of oxidized dNTPs, resulting in DNA damage and cell death. We validate MTH1 as an anticancer target in vivo and describe small molecules TH287 and TH588 as first-in-class nudix hydrolase family inhibitors that potently and selectively engage and inhibit the MTH1 protein in cells. Protein co-crystal structures demonstrate that the inhibitors bind in the active site of MTH1. The inhibitors cause incorporation of oxidized dNTPs in cancer cells, leading to DNA damage, cytotoxicity and therapeutic responses in patient-derived mouse xenografts. This study exemplifies the non-oncogene addiction concept for anticancer treatment and validates MTH1 as being cancer phenotypic lethal.

A homogeneous HTRF assay for the identification of inhibitors of the TWEAK-Fn14 protein interaction

The TWEAK-Fn14 pathway is upregulated in models of inflammation, autoimmune diseases, and cancer. Both TWEAK and Fn14 show increased expression also in the CNS in response to different stimuli, particularly astrocytes, microglia, and neurons, leading to activation of NF-κB and release of proinflammatory cytokines. Although neutralizing antibodies against these proteins have been shown to have therapeutic efficacy in animal models of inflammation, no small-molecule therapeutics are yet available. Here, we describe the development of a novel homogeneous time-resolved fluorescence (HTRF)-based screening assay together with several counterassays for the identification of small-molecule inhibitors of this protein-protein interaction. Recombinant HIS-TWEAK and Fn14-Fc proteins as well as FLAG-TWEAK and Fn14-FLAG proteins and an anti-Fn14 antibody were used to establish and validate these assays and to screen a library of 60 000 compounds. Two HTRF counterassays with unrelated proteins in the same assay format, an antiaggregation assay and a redox assay, were applied to filter out potential false-positive compounds. The novel assay and associated screening cascade should be useful for the discovery of small-molecule inhibitors of the TWEAK-Fn14 protein interaction.

Rates of metabolism of chlorzoxazone, dextromethorphan, 7-ethoxycoumarin, imipramine, quinidine, testosterone and verapamil by fresh and cryopreserved rat liver slices, and some comparisons with microsomes

In the present study we have investigated the disappearance of chlorzoxazone, dextromethorphan, 7-ethoxycoumarin, imipramine, quinidine, testosterone and verapamil from the medium in which fresh and cryopreserved rat liver slices were incubated. These compounds are all substrates of major isoforms of cytochrome P450 expressed in the liver. The metabolism of five of these compounds in microsomes from rat liver was also examined. Determinations of the concentrations of the compounds were performed employing LC/MS. Intrinsic clearance values (CL(ints)) were calculated on the basis of the concentration-vs.-time curves. No significant differences in the CL(int) values obtained with fresh and cryopreserved rat liver slices were observed for any of the compounds. The highest CL(int) value estimated with liver slices was observed for testosterone and the lowest values were with chlorzoxazone and 7-ethoxycoumarin. The total CL(int) values for 7-ethoxycoumarin and imipramine, calculated using scaling factors, were similar for liver slices and microsomes. In the case of testosterone, this total CL(int) was approximately 3.7-fold lower, whereas for dextromethorphan and quinidine it was 2.5- and 8.5-fold higher, respectively, with liver slices than with microromes. In conclusion, the rate of metabolism of the seven compounds tested with rat liver slices was not affected by cryopreservation. This finding adds further support to the general conclusion that the major activities involved in drug metabolism are not affected by cryopreservation of rat liver slices.

Experimental cancer cachexia: the role of host-derived cytokines interleukin (IL)-6, IL-12, interferon-gamma, and tumor necrosis factor alpha evaluated in gene knockout, tumor-bearing mice on C57 Bl background and eicosanoid-dependent cachexia

MCG 101 tumors were implanted sc. on wild-type C57 Bl and gene knockout mice to evaluate the role of host-produced cytokines [interleukin (IL)-6, IL-12, IFNgamma, tumor necrosis factor (TNF) receptor 1, and TNF receptor 2] to explain local tumor growth, anorexia, and carcass weight loss in a well-defined model with experimental cachexia. Indomethacin was provided in the drinking water to explore interactions between host and tumor-derived prostaglandins and proinflammatory cytokines for tumor growth. Wild-type tumor-bearing mice developed cachexia because of rapid tumor growth, which were both attenuated in IL-6 gene knockouts. Similar findings were observed after provision of anti-IL-6 to wild-type tumor-bearing mice. Alterations in food intake were not directly related to systemic IL-6 but rather secondarily to IL-6-dependent tumor growth. The absence of host-derived IL-12, IFN-gamma, or the TNF receptor 1 or receptor 2 gene did not attenuate tumor growth or improve subsequent cachexia. Thus, carcass weight loss was not improved by the omission of host cytokine (TNF-alpha, IL-12, or IFN-gamma) except for IL-6. Systemic indomethacin provision decreased plasma prostaglandin E2 in five of six groups of gene knockout tumor-bearing mice, which was associated with improved carcass weight in these groups. Indomethacin seemed to improve food intake to a similar extent in both wild-type and gene knockouts, which agree with the speculation that eicosanoids are more important to explain anorexia than host cytokines. Our results demonstrate that host- and tumor-derived cytokines and prostaglandins interact with tumor growth and promote cachexia in a more complex fashion than usually presented based on previous information in studies on either anti-cytokine experiments in vivo or on gene knockouts with respect to a "single cytokine model." Overall, host cytokines were quantitatively less important than tumor-derived cytokines to explain net tumor growth, which indirectly explains subsequent cachexia and anorexia.

Neuroendocrine peptide levels in the gastrointestinal tract of mice after unilateral cervical vagotomy

The effects of left and right unilateral cervical vagotomy on the content of several neuroendocrine peptides were studied in different parts of the murine gastrointestinal tract, known to receive vagal innervation. The neuroendocrine peptides investigated were secretin, gastric inhibitory peptide (GIP), gastrin, motilin, peptide YY (PYY), somatostatin, substance P, VIP, neurotensin, neuropeptide Y (NPY), and galanin. The neuroendocrine peptide concentration was affected after both left and right vagotomy, and that the changes in the concentrations of the neuroendocrine peptide levels occurred in all the gastrointestinal segments investigated, namely antrum, small and large intestine. However, these changes varied, depending on which side was vagotomized and the interval after vagotomy. It is concluded that the vagus nerve had an important impact on the neuroendocrine system in the murine gut. It is suggested, furthermore that the contradictory results obtained earlier on the effect of vagotomy on the gastrointestinal peptides may depend on differences in the vagotomy methods used and on differences in observation time after vagotomy.

Physiological changes in pigs exposed to a blast wave from a detonating high-explosive charge

The aim of this project was to study respiration, circulation, and brain activity in pigs during and after a blast wave exposure. Ten anesthetized pigs were used. Seven were exposed to blast and three were controls. Physiological parameters of respiration and circulation as well as cortical activity were followed from 30 minutes before until 120 minutes after the real or simulated blast. There were no significant changes in heart rhythm, cardiac output, arterial oxygen or carbon dioxide tension, blood pH, or mixed venous saturation during the experiment. The blast exposure caused intestinal injuries but no lung damage. A transient flattening of the electroencephalogram was seen immediately after the blast in four experimental animals, in contrast to the unchanged baseline electroencephalogram of the control animals. This momentary depression of cortical activity accompanied by short-lasting apnea indicates a blast wave-induced effect on the brainstem or higher controlling center.

Diaphragmatic activity after laparoscopic cholecystectomy

BACKGROUND

Laparoscopic cholecystectomy is presumed to induce a reduction in diaphragmatic activity. Indirect indices of diaphragmatic function based on tidal changes in pressures and cross-section area measurements can be unreliable in the postoperative phase. The present study evaluates diaphragmatic activity by directly recording diaphragmatic EMG (EMGdia) data, along with indirect indices.

METHODS

Thirteen adult patients (American Society of Anesthesiologists physical status I or II) undergoing laparoscopic cholecystectomy were examined preoperatively for inspiratory tidal changes in gastric (Pgas-insp) and esophageal (Peso-insp) pressures, and tidal changes in ribcage (Vthor) and abdominal (Vabd) cross-section areas and then again at 1, 6, and 24 h postoperatively combined with EMGdia recordings. Variations in inspiratory gastric (deltaPgas-insp) and inspiratory transdiaphragmatic (deltaPdi-insp) pressures were derived from the above.

RESULTS

Laparoscopic cholecystectomy induced a significant reduction in mean deltaPgas-insp, mean deltaPdi-insp, and mean Vabd indicating a reduction of diaphragmatic activity postoperatively. DeltaPdi-insp decreased from 11.8+/-4.0 cm H2O preoperatively to 5.7+/-5.7 cm H2O at 1 h and 6.6+/-5.1 cm H2O at 6 h postoperatively (mean +/- SD; P < 0.05). Vabd decreased from 327.0+/-113.0 ml preoperatively to 174.0+/-65.0 ml at 1 h and 175.0+/-98.0 ml at 6 h postoperatively (mean +/- SD; P < 0.05). These values had partially recovered at 24 h.

CONCLUSION

The direct and indirect indices of diaphragmatic activity taken together confirm the presence of reduction in diaphragmatic activity after laparoscopic cholecystectomy followed by its partial recovery at 24 h.

Effects of unilateral cervical vagotomy on antral endocrine cells in mouse

The present study was carried out to investigate the effect of unilateral cervical vagotomy on the antral endocrine cells in mouse. Fifty-four mice were randomly divided into three groups, 18 in each, for left or right cervical vagotomy, or sham operation as controls. The animals were sacrificed 2, 4, and 8 weeks after the operation, respectively. Chromogranin-, gastrin/CCK-, serotonin-, and somatostatin-cells were detected by immunohistochemistry and quantitated by computerised image analysis. The results showed that the number of chromogranin-cells was decreased in both left and right vagotomized mice after 4 weeks and remained at the same level after 8 weeks. The numbers of gastrin-, serotonin- and somatostatin-cells did not change after right vagotomy. However, the numbers of gastrin- and somatostatin-cells were decreased after left vagotomy, whereas no change was found in serotonin-cells. Endocrine cells with vacuolated cytoplasm and pyknotic nuclei were also observed during the course of time. The alteration in the antral endocrine cells observed in this study seemed to be dynamic and depended on the observation time after the operation as well as the denervated branches of the vagus nerve. This may explain, at least partially the contradictory results obtained earlier by different investigators.

Changes in intestinal endocrine cells in the mouse after unilateral cervical vagotomy

The effect of right or left unilateral cervical vagotomy on the intestinal endocrine cells was studied in 23 mice at 2 and 8 weeks after operation, respectively. The results were compared with that from 10 sham operated mice. Various types of endocrine cells in duodenum and proximal colon were detected by immunohistochemistry and quantified by computerized image analysis. In mouse duodenum, chromogranin-, CCK/gastrin-, GIP- and somatostatin-cells were significantly decreased at 2 weeks after right vagotomy, but returned to the control levels at 8 weeks. Serotonin-cells were reduced at both 2 and 8 weeks after right vagotomy. The amount of the duodenal endocrine cells did not change after left vagotomy with the exception of secretin-cells, which were diminished at 8 weeks after both right and left vagotomy. In the proximal colon, chromogranin-cells were also decreased at 2 weeks after right vagotomy. Serotonin-cells were reduced at 8 weeks after left vagotomy but not right vagotomy. There was no significant difference between the unilaterally vagotomized and the sham operated mice with regard to PYY- and glucagon-cells. It was concluded that vagotomy affected the intestinal endocrine cells in mouse. The influence was more pronounced in the small intestine than the proximal colon. The right vagus nerves seemed to exert more effect on the intestinal endocrine cells than the left ones.

Life expectancy and cost utility after total hip replacement

In a prospective study of 410 cemented hip replacements in 372 patients with a mean age of 71 years, mortality after 8 years was 33%. Mortality for patients with osteoarthrosis was lower than in an age matched control population, probably because of a preoperative selection of patients. An estimate of costs and adjusted quality of life has shown that total hip replacement has a good cost utility even in the elderly patient. The conclusion of this study is that the indications for hip replacement in the elderly patient can be expanded. Such patients should undergo surgery earlier in the course of their disease.

A one-piece plexiglass access chamber for subcutaneous implantation in the dorsal skin fold of the mouse

This technical report describes the production and installation of a newly developed, one-piece, light-weight (0.6 g) access plexiglass chamber for the dorsal skin fold of the mouse.

Chest wall velocity as a predictor of nonauditory blast injury in a complex wave environment

Previous blast injury prediction criteria have been based on exposure to classic Friedlander or ideal blast waves. An ideal waveform is characterized by an instantaneous rise to a peak overpressure that decays exponentially to ambient pressure followed by a negative phase. The prediction criteria did not address injuries resulting from exposure to complex blast waves. It was difficult to establish a simple relationship between the two because complex blast waves typically consist of multiple shocks with variable frequency content and intensity that may be superimposed on a slow rising quasistatic pressure pulse. This paper deals with the application of a single degree of freedom mathematical model, originally developed to measure the response of the thorax to Friedlander waves, to calculate chest wall velocities resulting from various complex blast loads. Experimental results with sheep, exposed to complex blast waves in enclosures, demonstrated that there was a good relationship between the Adjusted Severity of Injury Index (which includes injury to the lungs, upper respiratory tract, gastrointestinal tract and solid intraabdominal organs) and the calculated peak inward chest wall velocity. In addition, there was a good correlation between these results and previously established Friedlander injury prediction curves. The velocity of complex blast waves was nearly the same as that of Friedlander waves for a given degree of injury: 3-4.5 meters/second for threshold injury, 8-12 meters/second for an LD1, and 12-17 meters/second for an LD50.

CCK- and VIP-induced glycoprotein secretion from mouse gallbladder epithelium following vagotomy: a quantitative electron microscopic study

The glycoprotein secretion from the mouse gallbladder epithelium induced by vasoactive intestinal peptide (VIP) and cholecystokinin (CCK) was investigated by electron microscopic morphometry. Both VIP and CCK caused a decrease in the volume density of the glycoprotein-containing granules of the principal cells. The effect on the gallbladder epithelium of a left-sided vagotomy was examined. Three and six weeks postvagotomy, slight decreases in cell and nuclear profile area and secretory granule volume density were noted. CCK induced a secretion of glycoprotein granules, whereas no such secretory effect due to VIP could be detected in animals 3 and 6 weeks after vagotomy. The results demonstrate that VIP, like CCK, is involved in glycoprotein secretion from the mouse gallbladder epithelium, but the secretory effect of VIP would appear to be dependent on an intact vagal innervation. The results are of interest in relation to the hypothesis that glycoprotein release may be a precipitating factor in the production of gallstones.

Isoprenoid biosynthesis in multiple sclerosis, II. A possible role of NADPH

Genetic predisposition in MS, influence of fat consumption on the disease, and excretion of lipid metabolites in urine led us to investigate isoprenoid metabolism in this disease. Ubiquinone concentration and biosynthesis was normal in lymphocytes. Cytochrome oxidase, which contains an isoprenoid side chain, was normal in activity. Cholesterol biosynthesis from acetate was found to be elevated in MS, and so was triglyceride biosynthesis. Increased biosynthesis may offer a very simple explanation to all the metabolites excreted (3-methylglutaconic acid, 2-hydroxy-2-methyl-3-butenoic acid and adipic acid). Increased biosynthesis may be caused by an elevated NADPH/NADP ratio, since such an elevation may also account for many other biochemical anomalies in MS. Elevated NADPH/NADP ratio may be of direct importance in the pathogenesis.

Isoprenoid biosynthesis in multiple sclerosis

Recently discovered metabolites in urine have suggested a defect of isoprenoid metabolism in multiple sclerosis. Lymphocyte HMG-CoA reductase was found unaffected however, and so was lymphocyte biosynthesis of geraniol, farnesol and squalene from mevalonolactone. The level of dolichol in white matter of an MS brain was similar to that of a control sample. Serum ubiquinone, on the other hand, was decreased in multiple sclerosis. Ubiquinone in serum was both age-dependent and related to serum cholesterol. Active as well as stable MS displayed a decreased level of serum ubiquinone, and a reduced ubiquinone-cholesterol ratio. These results are compatible with a deficient ubiquinone biosynthesis in multiple sclerosis.

Glycoprotein secretion from mouse gallbladder principal cells after chronic variation in parasympathetic activity. A morphometric study after vagotomy and cholinergic superstimulation

Principal cells of mouse gallbladder epithelium were subjected to quantitative electron microscopic investigation either after superstimulation with pilocarpine for 12 days or 6 weeks after vagotomy at different levels. Cholinergic superstimulation caused a slight hypertrophy of the principal cells, whereas different types of vagotomy induced hypotrophic changes. In the superstimulated animals there was decreased sensitivity to single-dose stimulation with pilocarpine. In contrast, a supersensitivity was recorded in mice subjected to vagotomy. It is concluded that the parasympathetic nervous system is of importance for the regulation of glycoprotein secretion from mouse gallbladder principal cells. The demonstrated vagotomy-induced super-sensitivity may be responsible for an increased glycoprotein release, which in turn may be involved in the formation of gallstones occurring after truncal vagotomy in man.

Effect of vagus nerve stimulation on the secretory-granule volume of the principal cells of the mouse gallbladder epithelium

Experiments in mice were performed in order to investigate whether vagal activity could affect glycoprotein secretion from gallbladder principal cells. This cell type was studied with the electron microscope in control animals and after electric stimulation of the right or left nervus vagus. The volume density of glycoprotein containing granules was determined using morphometry. It was found that stimulation of the left vagus nerve significantly reduced the relative cellular volume of secretory granules in the principal cells of the gallbladder. Right vagus stimulation was accompanied by a weak but insignificant increase in secretory granule content. It is suggested that the left vagus nerve may exert a direct influence on glycoprotein secretion from gallbladder principal cells.

Secretory behavior and ultrastructural changes in mouse gallbladder principal cells after stimulation with cholinergic and adrenergic drugs. A morphometric study

Principal cells of mouse gallbladder epithelium were subjected to a quantitative electron microscope study after in vivo and in vitro exposure to pilocarpine, noradrenaline, atropine, and phenoxybenzamine. Stereologic measurements were performed on randomly selected principal cells, and special interest was paid to changes in the size of the secretory granule population of the cells. Thirty minutes after in vivo and in vitro stimulation with pilocarpine, there was a significant decrease of the volume density of the glycoprotein-containing granules in the principal cells. Thirty minutes after in vivo administration of the cholinergic antagonist atropine, a significant increase of this parameter was observed. In vitro incubation for 30 min with a combination of pilocarpine and atropine extinguished the pilocarpine-induced effect on the secretory granules. Noradrenaline and phenoxybenzamine (an alpha-adrenergic blocking agent) in vivo and in vitro (30 min) had no effect on the volume density of the secretory granules. The authors' findings suggest that principal cells of the mouse gallbladder epithelium exhibit an increased rate of secretion of glycoprotein granules after stimulation in vivo and in vitro with cholinergic agents, whereas adrenergic agents are without effect.

Aspergillosis of the maxillary sinus. Clinical and histopathological features of 4 cases and a review of the literature

Four patients with aspergillus maxillary sinusitis are reported and a review of the literature on aspergillus paranasal sinusitis during the last 10 years is presented. The patients had symptoms and X-ray findings similar to a chronic bacterial sinusitis. One patient had been operated upon 6 years previously due to a chronic sinusitis and 3 of the patients had been treated with broad-spectrum antibiotic drugs. Caldwell-Luc operations were performed, also to exclude malignant tumours. The aspergillus etiology of the sinuitis was discovered in routine stained sections by histo-pathological examination of the sinus mucosae. No recurrence of the fungus infection occurred after the Caldwell-Luc operation, which was valuable for the correct diagnosis as well as being the best suited therapy.

Light and electron microscopic observations of the autonomic innervation of the mouse gallbladder mucosa. A histochemical, cytochemical, and secretory study

The autonomic innervation of the mouse gallbladder mucosa was studied using histo- and cytochemical methods. In a light microscopic investigation the distribution of acetylcholinesterase (AChE) activity and formaldehyde-induced fluorescence was studied histochemically. Nerve fibres and small varicosities showed concentrations of AChE activity very close to the epithelium in the subepithelial connective tissue. No adrenergic nerves were observed in the mucosa. When using the electron microscope and employing the potassium permanganate fixation/staining technique only one sort of axonal enlargement was encountered, viz. the cholinergic type. These varicosities contained numerous agranular vesicles (500-600 A in diameter). No varicosities of the adrenergic (dense-cored vesicles) type were observed. Signs of increased secretory activity in the epithelium were observed in the first few minutes after cholinergic stimulation. After repeated in vivo stimulation, there was an almost total depletion of glycoprotein granules, best seen when using the cytochemical PA-CrA-silver technique. The findings suggest that the subepithelial connective tissue and the epithelium of the mouse gallbladder mucosa have a cholinergic innervation.

Surface structure of unused and used catheters. A scanning electron microscopic study

The surface structure of different catheter materials was investigated by scanning electron microscopy. Two catheter types were also examined after long-term use in three patients with chronic urinary tract infection. It was found that the amount of salt encrustation was more pronounced the higher the degree of catheter surface roughness.

Dislocated IUD and intrauterine ectopic pregnancy with uterine rupture

A case of uterine rupture due to an ectopic pregnancy in the uterine fundus is presented. A Lippes Loop was found rotated in the uterine cavity. A possible relation between implantation and the dislocated intrauterine device is proposed.