Workplace mistreatment and mental health in female surgeons in Pakistan.

BACKGROUND: Despite workplace mistreatment, which includes harassment, bullying and gender discrimination(GD)/bias, being serious problems for female surgeons, there are limited data from lower-middle-income countries like Pakistan. This study explored harassment and GD/bias experienced by female surgeons in Pakistan, and the effects of these experiences on mental health and well-being. METHODS: A nationwide survey was conducted between July and September 2019 in collaboration with the Association of Women Surgeons of Pakistan, an organization consisting of female surgeons and trainees in Pakistan. An anonymous online survey was emailed directly, disseminated via social media platforms (such as Facebook, Twitter and Instagram), and sent to surgical programmes in Pakistan. RESULTS: A total of 146 women surgeons responded to the survey; 67.1 per cent were trainees and the rest attending surgeons. Overall, 57.5 per cent of surgeons reported experiencing harassment, most common being verbal (64.0 per cent) and mental (45.9 per cent), but this mostly went unreported (91.5 per cent). On multivariable analysis adjusted for age and specialty, workplace harassment (odds ratio 2.02 (95 per cent c.i. 1.09 to 4.45)) and bullying (odds ratio 5.14 (95 per cent c.i. 2.00-13.17)) were significantly associated with severe self-perceived burnout, while having a support system was protective against feelings of depression (odds ratio 0.35 (95 per cent c.i. 0.16 to 0.74)). The overwhelming majority (91.3 per cent) believed that more institutional support groups were needed to help surgeons with stress reduction (78.8 per cent), receiving mentorship (74.7 per cent) and work-life balance (67.8 per cent). CONCLUSION: Workplace mistreatment, in particular harassment and bullying, has a damaging impact on the mental well-being of female surgeons, particularly trainees. The absence of support groups in Pakistan should be urgently addressed so that surgeons, especially trainees, may cope better with potentially harmful workplace stressors.

Aquaporin 1 regulates GTP-induced rapid gating of water in secretory vesicles.

The swelling of secretory vesicles has been implicated in exocytosis, but the underlying mechanism of vesicle swelling remains largely unknown. Zymogen granules (ZGs), the membrane-bound secretory vesicles in exocrine pancreas, swell in response to GTP mediated by a G(alpha)i3 protein. Evidence is presented here that the water channel aquaporin-1 (AQP1) is present in the ZG membrane and participates in rapid GTP-induced vesicular water gating and swelling. Isolated ZGs exhibit low basal water permeability. However, exposure of granules to GTP results in a marked potentiation of water entry. Treatment of ZGs with the known water channel inhibitor Hg2+ is accompanied by a reversible loss in both the basal and GTP-stimulatable water entry and vesicle swelling. Introduction of AQP1-specific antibody raised against the carboxyl-terminal domain of AQP1 blocks GTP-stimulable swelling of vesicles. Our results demonstrate that AQP1 associated at the ZG membrane is involved in basal as well as GTP-induced rapid gating of water in ZGs of the exocrine pancreas.

The native membrane fusion machinery in cells.

Recombinant SNAREs have been demonstrated as the minimal membrane fusion machinery. The participation of additional proteins in the regulation of membrane fusion has been suggested. In this study we provide nanometer-resolution images of native NSF oligomers and SNARE complexes isolated from neurons and the pancreas. Our study reveals the presence of new coiled rod-like structures in association with the SNARE complex only in neuronal tissue. Neuronal SNAREs were found coiled and super-coiled with these structures. The existence of NSF as pentamers in its native state is also demonstrated. The extent of coiling and super-coiling of SNAREs may regulate the potency and efficacy of membrane fusion in cells.

Crystal structure of a pol alpha family replication DNA polymerase from bacteriophage RB69.

The 2.8 A resolution crystal structure of the bacteriophage RB69 gp43, a member of the eukaryotic pol alpha family of replicative DNA polymerases, shares some similarities with other polymerases but shows many differences. Although its palm domain has the same topology as other polymerases, except rat DNA polymerase beta, one of the three carboxylates required for nucleotidyl transfer is located on a different beta strand. The structures of the fingers and thumb domains are unrelated to all other known polymerase structures. The editing 3'-5' exonuclease domain of gp43 is homologous to that of E. coli DNA polymerase I but lies on the opposite side of the polymerase active site. An extended structure-based alignment of eukaryotic DNA polymerase sequences provides structural insights that should be applicable to most eukaryotic DNA polymerases.

Functional consequences and exonuclease kinetic parameters of point mutations in bacteriophage T4 DNA polymerase.

Three groups of T4 DNA polymerase mutants were prepared and characterized. In the first group, Ala and Asn were substituted for four acidic residues in the exonuclease domain that were chosen on the basis of their sequence alignment with the Klenow fragment from Escherichia coli DNA polymerase I. Two divalent metal ions required for catalyzing the 3'-5' exonuclease reaction are ligated by carboxyl groups from these conserved Asp and Glu residues. The Ala and Asn replacements have a profound effect on the exonuclease activity of T4 DNA polymerase and also have a significant, but less pronounced influence on its polymerase activity which is located in a domain distal to the exonuclease region. The kcat values for the exonuclease reaction were reduced by 3-4 orders of magnitude by these replacements, but the values of Km(app) did not differ greatly from the wild-type enzyme. The second group consists of replacements of other residues, that are conserved in the exonuclease domain of eukaryotic DNA polymerases, but do not contribute to divalent metal ion coordination. Many of these alterations resulted in decreased exonuclease and/or polymerase activity. Mutants in the third group have substitutions of conserved residues in the polymerase domain which diminished polymerase and altered exonuclease activities. Our results, combined with structural data on crystals of protein N388, a truncated form of T4 DNA polymerase (Wang et al., 1996), show that: (i) the reduction in the relative specific exonuclease activities of mutants in the first group was significantly less than that of mutants in the Klenow fragment, despite the nearly identical geometric arrangement of the metal liganding groups in two proteins; (ii) altered residues, that affect exonuclease and/or polymerase activities in mutants of the second group, cluster within a small area of the exonuclease domain, suggesting that this area may be directly or indirectly involved in polymerase activity; (iii) mutations in the third group, which affect polymerase and exonuclease activities, may participate in DNA and dNTP binding. Our results point to the functional interdependence of the polymerase and exonuclease domains in T4 DNA polymerase, a property not observed with the Klenow fragment.

Mutagenesis of the COOH-terminal region of bacteriophage T4 regA protein.

The bacteriophage T4 regA protein is a translational repressor that regulates the synthesis of > 12 T4 proteins. Earlier studies demonstrated that photocross-linking of the 122-residue regA protein to (dT)16 occurs at two sites, with the major site occurring at Phe-106. Amino acid substitutions were introduced at Phe-106 to evaluate its role in nucleic acid binding. Binding affinities of mutants F106C, F106V, and F106Y for nonspecific and specific RNA ligands indicated little difference between the Kapp of the mutants and wild type regA protein, for either poly(U) or for a specific gene 44 oligoribonucleotide. Thus, Phe-106 does not contribute measurably to the overall free energy of binding. Partial proteolysis of regA protein was carried out to further probe its domain structure. Chymotryptic cleavage produced a fragment of 11,095 Da that has reduced affinity for poly(U) and that contains the first 93 residues of regA protein. Interestingly, proteolysis of regA protein is reduced in the presence of the specific target, gene 44 RNA. Two deletion mutants, 1-->94 and 1-->109, have also been cloned and purified. The binding affinities of these deletion mutants indicated a 100-1000-fold reduction in their affinities for poly(U). These studies indicate the last 13 amino acids in regA protein make a significant contribution to RNA binding.

Purification and characterization of an extracellular prolyl endopeptidase from Agaricus bisporus.

Prolyl endopeptidase [EC 3.4.21.26] was purified to homogeneity from the culture filtrate of Agaricus bisporus by a procedure that comprised ammonium sulfate fractionation, anion-exchange chromatographies on DEAE-Toyopearl and DEAE-Sephadex, hydroxylapatite chromatography, and high-performance liquid chromatography (HPLC) on a TSKgel G 2000 SW column. The overall activity recovery was 8.6%. The enzyme was most active at or around pH 7.5 and was stable in the range of pH 5-9 when checked with Z-Gly-Pro-beta-naphthylamide as a substrate. The isoelectric point of the enzyme was about 4.8. The enzyme was a monomeric protein of molecular weight 78,000 +/- 2,000 as judged by gel permeation chromatography on Sephadex G-150 and electrophoresis on sodium dodecyl sulfate (SDS) polyacrylamide gel. The enzyme hydrolyzed Pro-X bonds and at least five subsites (S3, S2, S1, S1', and S2') were found to be involved in enzyme-substrate binding. Among them, S2, S1, and S1' subsites of the enzyme showed high stereospecificity. The enzyme was strongly inhibited by diisopropylfluorophosphate (DFP), Z-Gly-Pro-CH2Cl, Z-Pro-prolinal, Z-Pro-pyrrolidine, Z-Thiopro-pyrrolidine, Z-Pro-thiazolidine, Z-Thioprothiazolidine, and p-chloromercuribenzoate (PCMB), while it was not inhibited by phenyl-methylsulfonyl fluoride (PMSF), E-64, iodoacetamide, or metal chelators. Although the A. bisporus enzyme showed no immunological cross reaction with anti-bovine prolyl endopeptidase antiserum, the other characteristics were quite similar to those of mammalian and plant enzymes.

Lyophyllum cinerascens aminopeptidase: purification and enzymatic properties.

An aminopeptidase (EC 3.4.11.1) was purified from the extract of Lyophyllum cinerascens by ammonium sulfate fractionation and sequential chromatographies on DEAE-Sephadex, Sephadex G-150, HPLC-phenyl-5PW, and HPLC-DEAE-5PW columns, with an activity recovery of 4.6% using Leu-beta-naphthylamide as a substrate. The enzyme was a tetrameric protein of molecular weight 150,000 and was found to be rich in histidine. It exhibited a pH optimum of 7.2 and stability between pH 5.7 and 7.7. The isoelectric point of the enzyme was 4.6. The enzyme catalyzed the hydrolysis of amino acid beta-naphthylamides, Phe greater than Leu greater than Met greater than Tyr greater than Ala greater than Glu, and the differences of the measured kcat's ranged over 2-3 orders of magnitude while many of the amino acid beta-naphthylamides were not hydrolyzed at all. Other interesting comparisons include two aliphatics, Ala vs Leu, and the aromatics, Tyr vs Phe, which show a 30-fold difference in the kcat/Km values. The enzyme also hydrolyzed Leu-Gly-Gly and the B chain of oxidized insulin to release N-terminal leucine and phenylalanine, respectively. The release of N-terminal Phe from the oxidized B chain is interesting in view of the fact that the penultimate residue is Val, an unfavorable amino acid in the beta-naphthylamide series. The enzyme seems to be a true aminopeptidase, requiring the free amino groups and hydrolyzing dipeptide and oligopeptide from the N-terminal end. The enzyme was resistant to the action of amastatin. Neither sulfhydryl reagents nor serine protease inhibitors affected the enzyme activity; however, the enzyme was inhibited weakly by EDTA and bestatin and strongly by diethyl pyrocarbonate.

Studies on prolyl endopeptidase from shakashimeji (Lyophyllum cinerascens): purification and enzymatic properties.

High prolyl endopeptidase (post-proline cleaving enzyme) [EC 3.4.21.26] activity was detected in fruit bodies of shakashimeji (Lyophyllum cinerascens), tsukuritake (mushroom: Agaricus bisporus), hirohachichitake (Lactarius hygrophoroides), and yaburebenitake (Russula lepida) which belong to the genus Basidiomycetes. Cell-free extract of shakashimeji showed high activities of proline iminopeptidase and arylamidase as well as prolyl endopeptidase. The prolyl endopeptidase was purified from the extract of shakashimeji by sequential chromatographies on DEAE-Toyopearl, DEAE-Sephadex and hydroxyapatite, and high-performance liquid chromatography with a DEAE-5PW column. The purified enzyme was homogeneous as judged by disc gel electrophoresis. The enzyme was most active at pH 6.8 as checked with Z-Gly-Pro-beta-naphthylamide as a substrate and was stable in the range of pH 5.8-7.4. The isoelectric point of the enzyme was 5.2 and the molecular weight was estimated to be 76,000 by gel filtration on Sephadex G-150 and by sodium dodecyl sulfate (SDS) gel electrophoresis, suggesting that the enzyme was a monomer. The enzyme was completely inhibited by diisopropyl fluorophosphate (DFP), Z-Gly-Pro-CH2Cl, and Z-Pro-prolinal, while it was not inhibited by p-chloromercuribenzoate (PCMB), phenylmethylsulfonyl fluoride (PMSF), or metal chelators. It was estimated that at least five subsites were concerned with the enzyme-substrate binding. Among them, the S1, S2, and S1' sites showed high stereospecificity, as in mammalian, microbial, and plant enzymes. The enzyme hydrolyzed TRH at the carboxyl side of the proline residue. The mushroom enzyme, that was sensitive to DFP, Z-Pro-prolinal, and Z-Gly-Pro-CH2Cl, but not to PCMB, were quite similar in characteristics to the Flavobacterium enzyme.(ABSTRACT TRUNCATED AT 250 WORDS)