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1.
Vet Parasitol ; 329: 110197, 2024 May 10.
Artigo em Inglês | MEDLINE | ID: mdl-38735268

RESUMO

We tested the hypothesis that age, breed, and sex are related to hematology, biochemistry, acute phase proteins (APPs), seroreactivity and level of parasitemia in dogs with an acute phase response (APR) due to Babesia canis infection. The study enrolled 61 privately owned dogs that naturally acquired B. canis infection. Groups were formed according to the age: young dogs less than one year, and adult dogs more than one year old. Moreover, the group of males was compared to females and purebred to mixed breed dogs. Seroreactivity was tested with immunofluorescence antibody test, level of parasitemia with real-time polymerase chain reaction (real-time PCR), hematology, and biochemistry with automatic analyzers, serum amyloid A with enzyme-linked immunosorbent assay, fibrinogen with heat precipitation and ceruloplasmin and paraoxonase-1 with manual spectrophotometric methods. For protein separation agarose gel electrophoresis was used. The main changes in the whole population of B. canis-infected dogs were fever, pancytopenia, and change in APPs level. One-third of young, and 96% of adult dogs were seropositive (P < 0.001). The level of parasitemia was higher in the young dogs (P < 0.001). Erythroid lineage parameters (P < 0.01), and leukocytes (P < 0.05) were lower in the young, when compared to the adult dogs. Young dogs had lower total globulins (P < 0.001), ß- and γ-globulins (P < 0.001), and higher α-globulins (P = 0.022) than adult dogs. Young dogs had higher concentrations of phosphate (P = 0.003) and cholesterol (P < 0.001) and lower amylase (P = 0.014) and lipase activity (P = 0.020) than adult ones. Male dogs had lower neutrophil count than females (P = 0.035), and purebred dogs had more band neutrophils than mixed breed dogs (P = 0.004). In conclusion, dogs with natural Babesia canis infection at a young age have more severe anemia and APR including leukopenia than adults. Male and purebred dogs might also have more severe APR than females and mix-breeds, as they have more pronounced changes related to the myeloid lineage.

2.
Res Vet Sci ; 165: 105076, 2023 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-37939632

RESUMO

Oxidative stress plays an important role in pathogenesis of idiopathic epilepsy (IE). Although IE is the most common neurological condition, oxidant-antioxidant status in epileptic dogs is still unknown. The aim of this study is to evaluate the serum oxidant-antioxidant status in dogs with newly diagnosed IE. The status in 15 dogs with IE and 15 healthy dogs is estimated through spectrophotometric determination of two oxidant markers: advanced oxidation protein products-albumin index (AOPP) and thiobarbituric acid reactive substances (TBARS); and three antioxidant markers: total thiols (R-SH) level, glutathione (GSH) level, and paraoxonase-1 (PON-1) activity. Also, butyrylcholinesterase (BChE) activity is assessed in both groups of dogs. Higher AOPP is observed in the dogs with newly diagnosed IE, while TBARS level shows no difference when compared to the healthy dogs. In contrast, lower levels of antioxidants (R-SH, GSH, and PON-1) and BChE activity are found in the dogs with IE. No significant differences are observed in the oxidant and antioxidant markers and BChE activity across the investigated IE cases with focal and generalized seizures. Our findings provide evidence that dogs with IE are characterized by an impaired serum oxidant-antioxidant balance and lower BChE activity, which may contribute to a better understanding of IE pathogenesis.


Assuntos
Doenças do Cão , Epilepsia , Cães , Animais , Antioxidantes/metabolismo , Butirilcolinesterase/metabolismo , Oxidantes , Projetos Piloto , Substâncias Reativas com Ácido Tiobarbitúrico/metabolismo , Produtos da Oxidação Avançada de Proteínas/metabolismo , Estresse Oxidativo , Glutationa/metabolismo , Epilepsia/veterinária
3.
Int J Clin Pharmacol Ther ; 61(4): 178-180, 2023 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-36633371

RESUMO

OBJECTIVE: We present a case of a patient who developed myasthenia gravis (MG)-like symptoms during erenumab treatment. CASE REPORT: The patient had a years-long history of chronic migraine with visual and sensory aura. Two months after the beginning of erenumab therapy, she reported intermittent bilateral weakness of the eyelids, with ptosis. The eyelid ptosis was severe enough to block the patient's vision. The symptoms would usually last between 5 and 10 minutes and resolve completely spontaneously, but they repeated on a daily basis. Antibodies against acetylcholine receptors and muscle-specific kinase were all negative, and other work-up excluded the usual etiology of ptosis. Since the cause of symptoms was not detected, we suspected they were induced by erenumab. The treatment was discontinued, and after 7 weeks from the last dose of erenumab, ocular symptoms resolved completely. In the presented case, other possible causes of MG-like symptoms were excluded by diagnostic tests and clinical course of the disease. The temporal relationship between the administration of erenumab and occurrence of ptosis, with regression of the symptoms after the drug discontinuation supports the hypothesis of causal relationship with erenumab. According to the Naranjo's Adverse Drug Reaction Probability Scale, erenumab-related MG-like symptoms were rated 'probable'. Reviewing the literature, we identified no similar case reports. CONCLUSION: Drug-induced MG-like symptoms might be life threatening. Therefore, clinicians should be aware of these adverse reactions during the use of erenumab.


Assuntos
Blefaroptose , Miastenia Gravis , Feminino , Humanos , Miastenia Gravis/induzido quimicamente , Miastenia Gravis/diagnóstico , Miastenia Gravis/tratamento farmacológico , Anticorpos Monoclonais Humanizados/farmacologia , Blefaroptose/induzido quimicamente , Blefaroptose/complicações , Blefaroptose/diagnóstico
4.
Vet Med Sci ; 9(1): 111-118, 2023 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-36580396

RESUMO

BACKGROUND: The epidemiological status concerning many canine tick-borne diseases (TBDs) in Serbia is still insufficiently known. OBJECTIVES: Our study aimed to investigate the presence of tick-borne pathogens of the family Anaplasmataceae and Hepatozoon spp., as a cause of illnesses accompanied by clinical signs that can occur in dogs with anaplasmosis, ehrlichiosis and hepatozoonosis. METHODS: Dogs are included in the study based on the presence of a minimum of three clinical and/or pathological findings that could be associated with anaplasmosis, ehrlichiosis and hepatozoonosis. During the study (April-October 2018), 11 dogs met the conditions to be included in the survey. Identification of the causative agent in the blood of diseased dogs was performed by conventional PCR followed by sequencing. RESULTS: The presence of the pathogens was confirmed in three animals (3/11, 27.3%). The presence of Ehrlichia canis was confirmed in 3-month-old female Rottweiler puppy, an 8-year old Miniature Schnauzer female was positive for Hepatozoon canis infection, while 4-year-old mixed breed male dog was co-infected with both mentioned pathogens. These are the first cases of autochthonous infection with E. canis and H. canis in dogs from Serbia confirmed by molecular methods. CONCLUSIONS: The results of our study indicate the importance of molecular methods to establish a reliable diagnosis of TBDs. Also, the confirmed presence of causative agents of canine monocytic ehrlichiosis and hepatozoonosis in Serbia appeals to veterinary practitioners that it is necessary to exclude the presence of those diseases in suspicious dogs.


Assuntos
Anaplasmose , Coccidiose , Doenças do Cão , Ehrlichiose , Doenças Transmitidas por Carrapatos , Carrapatos , Cães , Animais , Masculino , Feminino , Ehrlichia canis , Sérvia/epidemiologia , Doenças Transmitidas por Carrapatos/epidemiologia , Doenças Transmitidas por Carrapatos/veterinária , Ehrlichiose/diagnóstico , Ehrlichiose/epidemiologia , Ehrlichiose/veterinária , Coccidiose/epidemiologia , Coccidiose/veterinária , Doenças do Cão/diagnóstico , Doenças do Cão/epidemiologia
5.
Int J Biometeorol ; 66(4): 691-698, 2022 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-34997356

RESUMO

The highest number of acute Babesia canis cases in dogs is recorded over the February-May (Feb-May) period, which also represents the optimal climate conditions for tick activity in Belgrade, Serbia. A possibility that the acute phase response is more intense in dogs developing the disease in the Feb-May period compared with the response in other time periods of the year was tested. A total of 63 client-owned dogs with acute B. canis infection were enrolled and the routine hematology and biochemistry parameters-serum amyloid A (SAA), IgG against B. canis, level of parasitemia, ceruloplasmin (CER), paraoxonase-1 (PON-1), and fibrinogen-were measured. Acute phase indexes (API) were calculated as (SAA×CER)/(Iron×PON-1) and (SAA×CER)/(Albumin×Iron). Statistics included Kruskal-Wallis test and logistic regression analysis. The results showed that in the Feb-May period, the following parameters were lower: creatinine, albumin, iron, and level of parasitemia. Furthermore, increased API values were more probable in the Feb-May than in the other periods. Together, higher acute phase response intensity and presumptive hemodilution in the Feb-May period indicate a more acute course of B. canis infection than in other time periods of the year.


Assuntos
Babesia , Doenças do Cão , Reação de Fase Aguda/veterinária , Animais , Babesia/fisiologia , Cães , Estações do Ano , Sérvia
6.
Vet Parasitol ; 300: 109612, 2021 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-34735844

RESUMO

Inflammation is a hallmark of the acute Babesia canis infection. Promatrix metalloproteinase (proMMP)-2 and -9 are involved in inflammation, but their levels have not been analyzed in canine babesiosis. We hypothesized that in dogs infected with B. canis, serum proMMP-2 and -9 levels change between presentation and recovery. Degree of the change differs if dogs develop systemic inflammatory response syndrome (SIRS). This study included 24 dogs with an acute B. canis infection, at presentation and after two weeks. We used routine hematology and biochemistry methods, spectrophotometry for the acute-phase proteins, microscopy for parasitemia and zymography for (pro)MMPs. In vitro endothelial cells and leukocyte short-term cultures, and platelet lysates were used to detect specific MMP activity. Statistical analyses included Wilcoxon test for paired samples, Mann-Whitney U test and Spearman's rank correlation. Our results showed that endothelial cells, leukocytes and platelets are the source of proMMP-2 and proMMP-9. Furthermore, both proMMPs were lower at presentation than after recovery (p < 0.001). At presentation, proMMP-9 levels correlated with parasitemia (rho = -0.616, p = 0.009), total leukocyte (rho = 0.704, p < 0.001) and neutrophil counts (rho = 0.741, p < 0.001). Extent of alterations in proMMP-2 levels between presentation and recovery was lower (p = 0.038) in dogs with SIRS than in non-SIRS dogs, while levels of proMMP-9 were comparable between these groups. Our conclusion is that during the acute B. canis infection, low serum levels of proMMP-2 and proMMP-9 at presentation reflect thrombocytopenia and leukopenia. Decreased proMMP-2 level could be associated with SIRS.


Assuntos
Babesiose , Doenças do Cão , Metaloproteinase 2 da Matriz/sangue , Metaloproteinase 9 da Matriz/sangue , Animais , Babesia , Babesiose/sangue , Doenças do Cão/sangue , Doenças do Cão/parasitologia , Cães , Células Endoteliais
7.
Vet Parasitol ; 291: 109366, 2021 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-33545559

RESUMO

The common signs of canine babesiosis caused by an infection with Babesia canis are fever, anorexia, lethargy, pulse alterations, anemia, and occasionally mild icterus. Dogs with these clinical signs can be divided into two groups: those with acute-phase reaction and those with systemic inflammatory response syndrome (SIRS). Factors associated with the occurrence of SIRS in canine babesiosis have not been thoroughly researched. This article outlines a cross-sectional study of 54 client-owned dogs with an acute B. canis infection, and evaluates the differences in age, gender, laboratory findings, parasite load, and seroreactivity against B. canis between the SIRS and the SIRS-free dogs. We have analyzed a complete blood count, serum biochemistry, serum amyloid A, ceruloplasmin, paraoxonase-1, serology, and PCR testing using standard methodologies. The frequency of SIRS among the investigated dogs reached 0.59. Male dogs and those seronegative against B. canis, were more frequent in the SIRS group, whilst age and parasite load could not be associated with the presence of SIRS. Dogs with SIRS had a lower count of total leukocytes, neutrophils, lymphocytes, and monocytes, and a lower concentration of iron and bilirubin compared with SIRS-free dogs. No significant differences in the concentration of acute-phase proteins have been noticed to exist between the groups of dogs. Further, the seronegative dogs had a lower count of lymphocytes and monocytes and a higher parasite load than the seroreactive dogs. Multivariate logistic regression analysis has identified leukopenia (<6 × 109/L) and monocytopenia (<0.2 × 109/L) as independent associates of SIRS in the investigated dogs, thus implying that these routine tests could be used as reliable markers for SIRS.


Assuntos
Babesiose/complicações , Doenças do Cão/imunologia , Interações Hospedeiro-Parasita/imunologia , Carga Parasitária/veterinária , Síndrome de Resposta Inflamatória Sistêmica/veterinária , Animais , Babesia , Babesiose/imunologia , Babesiose/parasitologia , Biomarcadores/sangue , Doenças do Cão/parasitologia , Cães , Feminino , Masculino , Síndrome de Resposta Inflamatória Sistêmica/parasitologia
8.
World J Diabetes ; 11(11): 540-552, 2020 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-33269065

RESUMO

BACKGROUND: The sodium/glucose cotransporter-2 inhibitors (SGLT-2i) and glucagon-like-1 receptor agonists (GLP-1RA) are antidiabetic agents effective both in hemoglobin A1c (HbA1c) reduction (with a low risk of hypoglycemia) and cardiovascular event prevention. In patients with type 2 diabetes, the add-on value of combination therapy of GLP-1RA and an SGLT-2i seems promising. AIM: To investigate whether the efficacy of GLP-1RA and SGLT-2i combination observed in randomized controlled trials translates into therapeutic benefits in the Croatian population during routine clinical practice and follow-up. METHODS: We included 200 type 2 diabetes patients with poor glycemic control and analyzed the effects of treatment intensification with (1) GLP-1RA on top of SGLT-2i, (2) SGLT-2i on top of GLP-1RA compared to (3) simultaneous addition of both agents. The primary study endpoint was the proportion of participants with HbA1c < 7.0% and/or 5% bodyweight reduction. Secondary outcomes included changes in fasting plasma glucose (FPG), prandial plasma glucose, low-density lipoprotein cholesterol, estimated glomerular filtration rate (eGFR), and cardiovascular (CV) incidents assessment over a follow-up period of 12 mo. RESULTS: The majority of patients were over 65-years-old, had diabetes duration for more than 10 years. The initial body mass index was 39.41 ± 5.49 kg/m2 and HbA1c 8.32 ± 1.26%. Around half of the patients in all three groups achieved target HbA1c below 7%. A more pronounced decrease in the HbA1c seen with simultaneous SGLT-2i and GLP-1RA therapy was a result of higher baseline HbA1c and not the effect of initiating combination therapy. The number of patients achieving FPG below 7.0 mmol/L was significantly higher in the SGLT-2i group (P = 0.021), and 5% weight loss was dominantly achieved in the simultaneous therapy group (P = 0.044). A composite outcome (reduction of HbA1c below 7% (53 mmol/mol) with 5% weight loss) was achieved in 32.3% of total patients included in the study. Only 18.2% of patients attained composite outcome defined as HbA1c below 7% (53 mmol/mol) with 5% weight loss and low-density lipoprotein cholesterol < 2.5 mmol/L. There were no significant differences between treatment groups. No differences were observed regarding CV incidents or eGFR according to treatment group over a follow-up period. CONCLUSION: Combination therapy with GLP-1RA and SGLT-2i is effective in terms of metabolic control, although it remains to be determined whether simultaneous or sequential intensification is better.

9.
Acta Crystallogr B Struct Sci Cryst Eng Mater ; 75(Pt 3): 301-309, 2019 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-32830651

RESUMO

The interactions of nucleic acid bases with non-coordinated and coordinated water molecules were studied by analyzing data in the Protein Data Bank (PDB) and by quantum chemical calculations. The analysis of the data in the crystal structures from the PDB indicates that hydrogen bonds involving oxygen or nitrogen atoms of nucleic acid bases and water molecules are shorter when water is bonded to a metal ion. These results are in agreement with the quantum chemical calculations on geometries and interaction energies of hydrogen bonds; the calculations on model systems show that hydrogen bonds of nucleic acid bases with water bonded to a metal ion are stronger than hydrogen bonds with non-coordinated water. These calculated values are similar to the strength of hydrogen bonds between nucleic acid bases. The results presented in this paper may be relevant to understand the role of water molecules and metal ions in the process of replication and stabilization of nucleic acids and also to understand the possible toxicity of metal ion interactions with nucleic acids.


Assuntos
DNA/química , Metais/química , RNA/química , Água/química , Pareamento de Bases , Sítios de Ligação , Cristalização , Bases de Dados de Proteínas , Ligação de Hidrogênio , Íons/química , Teoria Quântica
10.
JFMS Open Rep ; 4(1): 2055116918770037, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-29854412

RESUMO

OBJECTIVES: The objectives of this study were to estimate the prevalence of feline haemoplasma infections in Northern Serbia, identify potential risk factors and perform molecular subtyping of feline immunodeficiency virus (FIV). METHODS: PCR analysis for feline haemoplasmas was performed on surplus EDTA blood samples from 373 cats from the Belgrade region, Serbia. An ELISA was used to determine the prevalence of feline leukaemia virus (FeLV) and FIV; PCR was performed on a subpopulation of these cats. FIV subtyping was performed using PCR. RESULTS: Within this population, 64/373 cats (17.2%) were infected with one or more haemoplasma species. Mycoplasma haemofelis was detected in 20/373 cats (5.4%), 'Candidatus Mycoplasma haemominutum' in 47/373 cats (12.6%) and 'Candidatus Mycoplasma turicensis' in 23/373 cats (6.2%). Coinfections were observed in 21/373 cats (5.6%). Based on ELISA serological retroviral testing, 4/310 cats (1.3%) were infected with FeLV, whereas 78/331 (23.6%) were infected with FIV. Multivariable analysis identified significant associations between haemoplasma infection and anaemia (anaemic/non-anaemic, odds ratio [OR] 2.7, 95% confidence interval [CI] 1.04-7.1; P = 0.041]), male gender (male/female, OR 4.5, 95% CI 2.22-9.03; P <0.0005), outdoor access (yes/no, OR 5.2, 95% CI 2.28-11.92; P <0.0005), non-pedigree breed (non-pedigree/pedigree, OR 5.5, 95% CI 1.24-24.84; P = 0.025) and FIV seropositive status (positive/negative, OR 2.4, 95% CI 1.21-4.83; P = 0.012). PCR analysis of the FIV ELISA-positive samples revealed clade D as being the most prevalent. CONCLUSIONS AND RELEVANCE: All three known species of feline haemoplasma were detected, confirming their presence in Serbia; 'Candidatus Mycoplasma haemominutum' was the most prevalent. We found a high prevalence of FIV-infected cats and FIV clade D was most prevalent.

11.
Acta Crystallogr B Struct Sci Cryst Eng Mater ; 74(Pt 3): 255-263, 2018 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-29927388

RESUMO

The interactions between phosphines and boranes in crystal structures have been investigated by analyzing data from the Cambridge Structural Database (CSD). The interactions between phosphines and boranes were classified into three types; two types depend on groups on the boron atom, whereas the third one involves frustrated Lewis pairs (FLPs). The data enabled geometric parameters in structures to be compared with phosphine-borane FLPs with classical Lewis pairs. Most of the crystal structures (78.1%) contain BH3 as the borane group. In these systems, the boron-phosphorus distance is shorter than systems where the boron atom is surrounded by groups other than hydrogen atoms. The analysis of the CSD data has shown that FLPs have a tendency for the longest boron-phosphorus distance among all phosphine-borane pairs, as well as different other geometrical parameters. The results show that most of the frustrated phosphine-borane pairs found in crystal structures are bridged ones. The minority of non-bridged FLP structures contain, beside phosphorus and boron atoms, other heteroatoms (O, N, S for instance).

12.
J Mol Model ; 24(3): 60, 2018 Feb 20.
Artigo em Inglês | MEDLINE | ID: mdl-29464387

RESUMO

Edge-to-face interactions between two pyridine molecules and the influence of simultaneous hydrogen bonding of one or both of the pyridines to water on those interactions were studied by analyzing data from ab initio calculations. The results show that the edge-to-face interactions of pyridine dimers that are hydrogen bonded to water are generally stronger than those of non-H-bonded pyridine dimers, especially when the donor pyridine forms a hydrogen bond. The binding energy of the most stable edge-to-face interacting H-bonded pyridine dimer is -5.05 kcal/mol, while that for the most stable edge-to-face interacting non-H-bonded pyridine dimer is -3.64 kcal/mol. The interaction energy data obtained in this study cannot be explained solely by the differences in electrostatic potential between pyridine and the pyridine-water dimer. However, the calculated cooperative effect can be predicted using electrostatic potential maps.

13.
Waste Manag ; 78: 426-433, 2018 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-32559929

RESUMO

A clear understanding of the characteristics of generated household food waste (HFW) is necessary to formulate an effective food waste management policy. The present study has focused on the quantity and composition of generated HFW as well as the driving forces, and further explored potential means of reducing HFW. The quantity of avoidable HFW generated in Shenzhen City in 2015 was estimated to be two-fold greater than that in 2001, which consequently produced 1,378 thousand metric tonnes CO2 eq. emissions during their ultimate waste disposal. This suggests that HFW prevention can yield great environment benefits by reducing carbon emissions. Based on a survey in which 418 households in Shenzhen City participated, it was apparent that both household size and income are the major drivers to HFW generation. A substantial reduction in HFW generation can be achieved through improvements in consumer behaviors, consciousness and attitudes. Priority should be given to the strategies that can increase people's awareness of HFW induced problems, with the purposes to achieve a more sustainable development.

14.
Ticks Tick Borne Dis ; 8(6): 907-914, 2017 10.
Artigo em Inglês | MEDLINE | ID: mdl-28802807

RESUMO

Babesia canis and Dirofilaria immitis are emerging and geographically overlapping vector-borne pathogens in dogs. Infection with B. canis leads to acute-phase response (APR) that can be mild to severe and results in either non-complicated or complicated forms of the disease. The aim of this study was to determine whether acute B. canis infection is more severe in dogs with underlying asymptomatic D. immitis infection. Dogs of both sexes, different ages and breeds, with naturally occurring mono-infections with B. canis (n=13) and D. immitis (n=18) and co-infected dogs (n=7) were enrolled as well as healthy controls (n=15). Routine haematology and biochemistry, agarose gel electrophoresis (agEF) protein fraction separation and enzyme-linked immunosorbent assay (ELISA) for serum amyloid A (SAA) were performed. Based on clinical and laboratory findings, sepsis was diagnosed in the majority of dogs with acute B. canis infection with or without underlying asymptomatic D. immitis infection. Overall, haematology, biochemistry and agEF pattern changes were induced and dictated by acute B. canis infection whether or not the dogs had an asymptomatic D. immitis infection. D. immitis infection slightly influenced the level of anaemia, slightly aggravated the level of dehydration and increased the concentration of γ-globulins in acute-phase B. canis infection. D. immitis infection prevented B. canis-induced leukopenia. SAA equally increased in dogs with acute B. canis infection with or without underlying D. immitis infection. The level of SAA was not changed in dogs with asymptomatic D. immitis when compared to the controls. In conclusion, asymptomatic D. immitis infection does not influence overall APR after acute B. canis infection.


Assuntos
Reação de Fase Aguda/veterinária , Babesiose/imunologia , Coinfecção/veterinária , Dirofilariose/imunologia , Doenças do Cão/imunologia , Proteína Amiloide A Sérica/metabolismo , Doença Aguda , Reação de Fase Aguda/imunologia , Reação de Fase Aguda/parasitologia , Animais , Infecções Assintomáticas , Babesia/fisiologia , Babesiose/parasitologia , Coinfecção/imunologia , Coinfecção/parasitologia , Dirofilaria immitis/fisiologia , Dirofilariose/parasitologia , Doenças do Cão/parasitologia , Cães , Feminino , Masculino
15.
Chemphyschem ; 17(13): 2035-42, 2016 07 04.
Artigo em Inglês | MEDLINE | ID: mdl-26989883

RESUMO

The hydrogen bonding of noncoordinated water molecules to each other and to water molecules that are coordinated to metal-ion complexes has been investigated by means of a search of the Cambridge Structural Database (CSD) and through quantum chemical calculations. Tetrahedral and octahedral complexes that were both charged and neutral were studied. A general conclusion is that hydrogen bonds between noncoordinated water and coordinated water are much stronger than those between noncoordinated waters, whereas hydrogen bonds of water molecule in tetrahedral complexes are stronger than in octahedral complexes. We examined the possibility of correlating the computed interaction energies with the most positive electrostatic potentials on the interacting hydrogen atoms prior to interaction and obtained very good correlation. This study illustrates the fact that electrostatic potentials computed for ground-state molecules, prior to interaction, can provide considerable insight into the interactions.

16.
Phys Chem Chem Phys ; 16(23): 11173-7, 2014 Jun 21.
Artigo em Inglês | MEDLINE | ID: mdl-24805772

RESUMO

The data from protein structures from the Protein Data Bank and quantum chemical calculations indicate the importance of aromatic-aromatic interactions at large horizontal displacements (offsets). The protein stacking interactions of the phenylalanine residue show preference for large offsets (3.5-5.0 Å), while the calculations show substantially strong interactions, of about -2.0 kcal mol(-1).


Assuntos
Benzeno/química , Proteínas/química , Teoria Quântica , Bases de Dados de Proteínas , Fenilalanina/química , Propriedades de Superfície
17.
Chemphyschem ; 14(1): 237-43, 2013 Jan 14.
Artigo em Inglês | MEDLINE | ID: mdl-23090910

RESUMO

A study of crystal structures from the Cambridge Structural Database (CSD) and DFT calculations reveals that parallel pyridine-pyridine and benzene-pyridine interactions at large horizontal displacements (offsets) can be important, similar to parallel benzene-benzene interactions. In the crystal structures from the CSD preferred parallel pyridine-pyridine interactions were observed at a large horizontal displacement (4.0-6.0 Å) and not at an offset of 1.5 Å with the lowest calculated energy. The calculated interaction energies for pyridine-pyridine and benzene-pyridine dimers at a large offset (4.5 Å) are about 2.2 and 2.1 kcal mol(-1), respectively. Substantial attraction at large offset values is a consequence of the balance between repulsion and dispersion. That is, dispersion at large offsets is reduced, however, repulsion is also reduced at large offsets, resulting in attractive interactions.


Assuntos
Benzeno/química , Modelos Moleculares , Piridinas/química , Simulação por Computador , Bases de Dados de Compostos Químicos , Dimerização , Ligação de Hidrogênio , Termodinâmica
18.
Phys Chem Chem Phys ; 14(31): 10896-8, 2012 Aug 21.
Artigo em Inglês | MEDLINE | ID: mdl-22772777

RESUMO

The geometry of hydrogen bonds in the crystal structures from the Cambridge Structural Database and calculated data show that water coordination to a metal ion has a remarkable influence on hydrogen bonds. The calculated energies of hydrogen bonds of coordinated water are much stronger, even if the aqua complex is neutral.


Assuntos
Metais/química , Água/química , Bases de Dados Factuais , Ligação de Hidrogênio , Íons/química , Modelos Moleculares
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