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BACKGROUND: Clinical outcome assessments provide important input for the rehabilitation of individuals with transfemoral amputation. Differences in prosthetic knee designs may influence clinical outcomes. OBJECTIVES: The aim of this study was to compare functional mobility, balance, prosthetic satisfaction and quality of life in individuals with unilateral transfemoral amputation with microprocessor-controlled (MPK) and non-microprocessor knee designs (Non-MPK). METHODOLOGY: The study included ten experienced MPK (Rheo Knee) users (Group 1) and ten experienced Non-MPK (Total Knee® 2000) users (Group 2). For mobility; the 6 Minute Walk Test (6MWT), for balance; the Berg Balance Scale (BBS), Single Leg Stand Test (SLST) and Four Square Step Test (FSST), for quality of life; the Nottingham Health Profile (NHP) and for prosthetic satisfaction; the Satisfaction with Prosthesis Questionnaire (SATPRO) were administered. FINDINGS: 6MWT results of the MPK group were significantly higher than Non-MPK group (p<0.05). In the MPK group a strong negative correlation was found between the FSST and the 6MWT (r=-0.661, p=0.038). No statistically significant differences were found between the groups (p>0.05) comparing balance, prosthesis satisfaction and quality of life values. CONCLUSION: The findings will inform about the patient's prognosis and the expected clinical outcomes when prescribing an MPK or an Non-MPK. Individuals with unilateral transfemoral amputation covered longer distances using an MPK compared to Non-MPK.
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BACKGROUND: Ischemia-reperfusion (I/R) injury is a common cause of patient morbidity and mortality in the perioperative period. Patients undergoing long-lasting, abdominal, and urogenital surgeries with risk factors such as advanced age, peripheral artery disease, diabetes mellitus, renovascular disease, and congestive heart failure are candidates for acute kidney injury (AKI) due to impaired renal perfusion and decreased functional renal reserve. Pharmacological agents with multiple functions and anti-oxidative and anti-inflammation properties may be promising preventative strategies for AKI. Recently, dexmedetomidine (dex) has been postulated to have renoprotective effects. OBJECTIVES: We aimed to investigate the protective effects of an intravenous anesthetic remifentanil in renal I/R injury in the rat in comparison with dex. MATERIALS AND METHODS: A total of 30 Sprague Dawley adult rats were randomly assigned into five groups: the control group (group C, n=6), the sham group (group Sh, n=6, saline-infused rats without I/R injury), the saline group (group S, n=6, saline-infused rats with I/R injury), the remifentanil-treated group (group REM, n=6), and the dexmedetomidine-treated group (group DEX, n=6). The infusions (saline, remifentanil, and dex) were started after anesthesia induction and right nephrectomy and continued until the end of the surgical procedure. In I/R injury groups, the left renal artery and vein were occluded together by a clamp for 30 minutes and reperfusion lasted for 30 minutes. The rats were sacrificed after reperfusion, and the left kidney tissue was harvested. Blood samples were drawn from all animals to evaluate plasma neutrophil gelatinase-associated lipocalin (NGAL) at the beginning, 15 minutes after ischemia, 15 minutes after reperfusion, and 6 hours after the surgical procedure (T0, T1, T2, and T3, respectively). RESULTS: The plasma NGAL levels exhibited increase at T1, T2, and T3 compared to the levels at T0 in group S (P<0.05). In group REM, there was a significant increase in plasma NGAL levels at T3 in comparison to those at T0, T1, and T2. The plasma NGAL levels at T2 in group S were significantly higher than those at T2 in group DEX (P<0.05). The groups S and REM showed significantly higher plasma NGAL levels at T3 compared to those at T0 (P<0.05). Upon histological examination, there was no difference among the study groups when left kidneys were evaluated (P>0.05). CONCLUSION: The NGAL levels and histopathological findings reflected protection by dex against renal I/R injury. However, the same exact results could not be mentioned for remifentanil depending on our study results.
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Analgésicos Opioides/uso terapêutico , Dexmedetomidina/uso terapêutico , Rim/efeitos dos fármacos , Piperidinas/uso terapêutico , Traumatismo por Reperfusão/tratamento farmacológico , Analgésicos Opioides/administração & dosagem , Animais , Dexmedetomidina/administração & dosagem , Injeções Intravenosas , Rim/lesões , Rim/patologia , Piperidinas/administração & dosagem , Ratos , Ratos Sprague-Dawley , Remifentanil , Traumatismo por Reperfusão/patologiaRESUMO
OBJECTIVE: The increasing prevalence of resistant microorganisms forced scientists to find new antimicrobial substances from different sources like medicinal plants. The aim of this study was to determine the antimicrobial activities of leaf extracts of some Alnus sp. against some bacteria and a yeast. MATERIALS AND METHODS: Aqueous and ethanolic leaf extracts of A. glutinosa subsp. glutinosa, A. orientalis var. orientalis, A. orientalis var. pubescens were screened for their antimicrobial activities against Staphylococcus aureus ATCC 25923, S. aureus ATCC 43300 (MRSA), Bacillus subtilis ATCC 6633, Escherichia coli ATCC 25922, Pseudomonas aeruginosa ATCC 27853 and Candida albicans ATCC 10231. Broth dilution method was used to determine the antimicrobial activities of plant extracts. RESULTS: Ethanolic extracts of tested species exhibited better antimicrobial activity than aqueous extracts. Ethanolic extracts of tested species possessed activity having MIC values of 0.125-0.250 mg/ml against the tested microorganisms. No antibacterial activity was observed against B. subtilis, E. coli, P. aeruginosa for all the aqueous extracts. Except these aqueous extracts, the others possessed activity having MIC value of 1.000 mg/ml against the tested microorganisms. CONCLUSIONS: To our knowledge, this is the first investigation on the evaluation of antimicrobial activities on aqueous and ethanolic leaf extracts of these species. This study provides significant information about antimicrobial activities of leaf extracts of A. glutinosa subsp. glutinosa, A. orientalis var. orientalis, A. orientalis var. pubescens. It is conceivable that one of the reason for the usage of Alnus glutinosa, in treatment of wound healing in folk medicine, is because of its antimicrobial activity.
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Alnus/química , Anti-Infecciosos/farmacologia , Extratos Vegetais/farmacologia , Plantas Medicinais/química , Anti-Infecciosos/isolamento & purificação , Candida albicans/efeitos dos fármacos , Candida albicans/crescimento & desenvolvimento , Escherichia coli/efeitos dos fármacos , Escherichia coli/crescimento & desenvolvimento , Medicina Tradicional/métodos , Testes de Sensibilidade Microbiana , Extratos Vegetais/isolamento & purificação , Folhas de Planta/química , Pseudomonas aeruginosa/efeitos dos fármacos , Pseudomonas aeruginosa/crescimento & desenvolvimento , Staphylococcus aureus/efeitos dos fármacos , Staphylococcus aureus/crescimento & desenvolvimentoRESUMO
AIM: In this study, we aimed to evaluate the diagnostic accuracy of elastosonography (ESG) scoring and strain ratio in patients who had atypia of undetermined significance (AUS) cytology and underwent surgery for thyroid nodules. MATERIALS AND METHODS: 250 patients were included in this study. They had at least one nodule in thyroid USG, underwent USG-guided FNAC according to the current guidelines and had AUS cytology according to the Bethesda system. Both elastosonographic color scoring and strain index were evaluated. RESULTS: A total of 270 nodules in 250 patients were evaluated. Histopathologically, 81 (30 %) nodules were malignant and 189 (70 %) were benign. According to the ESG, 10 (3.7 %) nodules were assigned a score of 1, while 13 (4.8 %) nodules were assigned a score of 5. All of the nodules with an ESG score of 1 were histopathologically benign and 92.3 % of the patients with ESG score 5 were in the malignant group. Median SI in the benign histopathologic group was significantly lower compared to malignant group [(2.58 (IQR = 2.35) vs. 14.54 (IQR = 10.71)]. The optimal SI cut-off value to distinguish between the benign and malignant nodules was 6.66, with a sensitivity of 98.77 % and specificity of 96.30 %. CONCLUSION: Our study is one of the first studies evaluating the role of SI for discriminating malignant and benign nodules with AUS cytology. Malignant nodules had a significantly higher stiffness compared to benign ones and SI had high sensitivity, specificity, positive predictive value, negative predictive value and accuracy for these nodules. We think SI may be helpful for the presurgical selection of nodules with AUS cytology.
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Técnicas de Imagem por Elasticidade , Neoplasias da Glândula Tireoide/diagnóstico por imagem , Nódulo da Glândula Tireoide/diagnóstico por imagem , Adolescente , Adulto , Idoso , Biópsia por Agulha Fina/métodos , Feminino , Indicadores Básicos de Saúde , Humanos , Masculino , Pessoa de Meia-Idade , Projetos de Pesquisa , Neoplasias da Glândula Tireoide/epidemiologia , Neoplasias da Glândula Tireoide/patologia , Nódulo da Glândula Tireoide/epidemiologia , Nódulo da Glândula Tireoide/patologia , Ultrassonografia de Intervenção , Adulto JovemRESUMO
OBJECTIVES: We aimed to determine whether the presence of Hürthle cells altered the distribution of categories in the Bethesda system for reporting thyroid cytopathology, or the expected neoplastic and malignant outcome. METHODS: Fine needle aspiration (FNA) cytology reports of Hürthle cells in a 2-year period were evaluated. The distribution of Bethesda system categories and the outcome at partial or complete thyroidectomy were compared for FNAs with and without Hürthle cells. RESULTS: Of 895 adequate FNAs with Hürthle cells, 764 (85.4%) were classified as benign, 86 (9.6%) as atypia of undetermined significance/follicular lesion of undetermined significance (AUS/FLUS), 32 (3.6%) as follicular neoplasm/suspicious for follicular neoplasm (FN/SFN), 12 (1.3%) as suspicious for malignancy (SFM) and one (0.1%) as malignant. Of 10 359 adequate FNAs without Hürthle cells, 9707 (93.7%) were classified as benign, 412 (4.0%) as AUS/FLUS, 77 (0.7%) as FN/SFN, 93 (0.9%) as SFM and 70 (0.7%) as malignant. The distribution of categories in FNAs with and without Hürthle cells was significantly different (P < 0.001) as a result of a decrease in benign and an increase in AUS/FLUS and FN/SFN categories. Among 128 patients with and 582 without Hürthle cells undergoing surgery, the overall neoplastic and malignancy rates were higher in the former than in the latter group (27.3% versus 14.9%, P < 0.001; 21.1% versus 11.7%, P = 0.003; respectively). Although neoplastic and malignant rates were higher in the group with than without Hürthle cells in all categories, the differences were only significant for a neoplastic outcome of benign cytology (15.1% versus 6.0%, P = 0.0013) and a malignant outcome of FN/SFN cytology (63.6% versus 21.9%, P = 0.0108). CONCLUSIONS: We found that the rates of AUS/FLUS and FN/SFN categories in the Bethesda system were higher when Hürthle cells were present. After surgery, neoplastic and malignant outcomes were significantly higher in the Hürthle cell group.
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Adenocarcinoma Folicular/diagnóstico , Biópsia por Agulha Fina , Citodiagnóstico , Neoplasias da Glândula Tireoide/diagnóstico , Adenocarcinoma Folicular/patologia , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Células Oxífilas/patologia , Glândula Tireoide/patologia , Neoplasias da Glândula Tireoide/patologia , Nódulo da Glândula Tireoide/patologiaRESUMO
OBJECTIVE: To report our experience of atypia of undetermined significance (AUS)/follicular lesion of undetermined significance (FLUS) rate and outcome. METHODS: Among 7658 patients with 19 569 nodules, 524 (2.7%) nodules were diagnosed as AUS/FLUS on fine needle aspiration (FNA). After exclusion of patients with simultaneous nodules that were suspicious for follicular neoplasm or malignancy or that were malignant, 368 (4.8%) patients were diagnosed as AUS/FLUS. The outcome of 146 patients who had undergone surgery or repeated fine needle aspirate at the time of preparation of this study was evaluated. The original FNAs were matched to repeated FNAs and thyroidectomy or diagnostic lobectomy specimens. RESULTS: Seventy-two (19.6%) of the 368 patients had directly undergone surgery, either a lobectomy or a thyroidectomy: of these, 27 (37.5%) had neoplastic nodules (21 were malignant). Seventy-four (20.1%) of the 368 patients had repeat FNA. On second FNA, 47 of 74 (63.5%) were benign, three were suspicious for follicular neoplasm, one was malignant and 23 (31.1%) were non-diagnostic. Four patients had a third FNA: two were AUS/FLUS, one was malignant and one non-diagnostic. One patient had a fourth FNA, which was diagnosed as AUS/FLUS. Sixteen (21.6%) of 74 patients with repeat FNA had surgery: three of these had neoplastic nodules (two were malignant). Overall, 88 of the 368 (23.9%) patients had a thyroidectomy of which 30 (34.1%) were neoplastic and 23 (26.1%) malignant. The neoplastic rate for patients who were once diagnosed with AUS/FLUS was 8.2% and the malignancy rate 6.3%. The malignancy rate for patients on follow-up at the time we prepared the study was 15.7% (23/146); 222 remained on follow-up without surgery or repeat FNA or were managed elsewhere. CONCLUSIONS: Although in this category repeat FNA is expected rather than excision, we suggest evaluation of all AUS/FLUS patients in multidisciplinary meetings to decide management and recommend follow-up of all patients with this diagnosis.
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Adenocarcinoma Folicular/patologia , Glândula Tireoide/patologia , Neoplasias da Glândula Tireoide/patologia , Nódulo da Glândula Tireoide/patologia , Adenocarcinoma Folicular/diagnóstico , Adenocarcinoma Folicular/cirurgia , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Biópsia por Agulha Fina/métodos , Feminino , Seguimentos , Humanos , Masculino , Pessoa de Meia-Idade , Estudos Retrospectivos , Glândula Tireoide/cirurgia , Neoplasias da Glândula Tireoide/diagnóstico , Neoplasias da Glândula Tireoide/cirurgia , Nódulo da Glândula Tireoide/diagnóstico , Nódulo da Glândula Tireoide/cirurgia , Tireoidectomia/métodos , Adulto JovemRESUMO
INTRODUCTION: A proper detection of atypical epithelial hyperplasia (component of FCC) without missing the coexistent malign disease is the main problem in evaluating the FCC-affected patients. For some patients, it is not enough to use only mammography and ultrasonography in pursuit or decision biopsy. Magnetic resonance imaging (MRI) may be important in these patients. Nevertheless, the MRI features of FCC are not clearly known because there are very few studies specifically focused on FCC. Studies reporting on MRI of breast fibrocystic changes are very scarce and their MRI findings are not clearly known. The aim of this study was to determine the MRI characteristics of fibrocystic changes. METHODS: Twenty-six patients with pathologically proven fibrocystic changes of the breast were retrospectively reviewed. The MRI study was performed using 1.5 T MR scanner with a phase array bilateral breast coil. The imaging protocol consisted of pre-contrast T1-weighted imaging and bilateral dynamic 3D contrast-enhanced imaging. The morphologic and kinetic features of fibrocystic changes on MRI were evaluated. RESULTS: Twenty-four patients showed benign enhancement kinetics (type 1), while 2 patients showed malignant enhancement kinetics (type 2). CONCLUSION: To our knowledge, the analysis of enhancement kinetics may be more useful in identifying atypical epithelial hyperplasia and cancer from other breast lesions provided that corrections are made for the true phase of menstrual cycle (Tab. 1, Fig. 1, Ref. 10).
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Doença da Mama Fibrocística/diagnóstico , Imageamento por Ressonância Magnética , Adulto , Feminino , Doença da Mama Fibrocística/diagnóstico por imagem , Humanos , Pessoa de Meia-Idade , Ultrassonografia MamáriaRESUMO
Endometriosis is characterized by the presence of histological normal endometrial tissue outside the uterine cavity. It occurs in up to 15% of menstruating women and often goes undetected. Some cases of soft-tissue involvement have been reported, particularly in the skin and subjacent tissues of surgical scars. However, we came cross a 42-year-old female patient with millimetric focal lesions in a groin hernia sac. A case report and a review of the literature are presented. Although definitive diagnosis still requires biopsy, the patient's cyclic symptoms and history of previous uterine surgery should suggest the correct diagnosis.
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Endometriose/patologia , Virilha/patologia , Hérnia Inguinal/patologia , Adulto , Biópsia , Endometriose/cirurgia , Feminino , Virilha/cirurgia , Hérnia Inguinal/cirurgia , Humanos , LaparoscopiaRESUMO
Although common in sheep-breeding communities, hydatid disease is actually found worldwide. Man is an occasional intermediate host in whom the disease is manifested by the presence of one or more hydatid cysts, usually located in the liver or lung and rarely at other sites such as the breast, as in our patient. A case of an isolated breast involvement that was diagnosed during surgery is presented and is followed by a brief discussion on the topic.
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Doenças Mamárias/diagnóstico , Equinococose/diagnóstico , Adulto , Doenças Mamárias/diagnóstico por imagem , Doenças Mamárias/cirurgia , Equinococose/diagnóstico por imagem , Equinococose/cirurgia , Feminino , Humanos , UltrassonografiaRESUMO
Transposon mutagenesis was employed to isolate the gene(s) related with the biosynthesis of dipeptide antibiotic in Bacillus subtilis PY79 (a prototrophic derivative of the standard 168 strain). The blocked mutants were phenotypically selected from the transposon library by bioassay and the complete loss of biosynthetic ability was verified through ESI-mass spectrometry analysis. Four different bacilysin nonproducer mutants (Bac(-)::Tn10(ori-spc)) were isolated from the transposon library. The genes involved in bacilysin biosynthesis were identified as thyA (thymidilate synthetase), ybgG (unknown; similar to homocysteine methyl transferase) and oppA (oligopeptide permease), respectively. The other blocked gene was yvgW (unknown; similar to heavy metal-transporting ATPase); however, backcross studies did not verify its involvement in bacilysin biosynthesis. This gene, on the other hand, appeared to be necessary for efficient sporulation and transformation. Opp involvement was significant as it suggested that bacilysin biosynthesis is under or a component of the quorum sensing pathway which has been shown to be responsible for the establishment of sporulation, competence development and onset of surfactin biosynthesis. For verification, it was necessary to check the involvement of peptide pheromones (PhrA or PhrC) internalized by the Opp system and response regulator ComA as the essential components of this global control. phrA, phrC and comA deleted mutants of PY79 were thus constructed and the latter two genes were shown to be essential for bacilysin biosynthesis.
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Transportadores de Cassetes de Ligação de ATP , Bacillus subtilis/genética , Proteínas de Bactérias/fisiologia , Proteínas de Ligação a DNA/fisiologia , Dipeptídeos/biossíntese , Proteínas de Escherichia coli , Genes Bacterianos/fisiologia , Proteínas Repressoras , Bacillus subtilis/metabolismo , Proteínas de Bactérias/genética , Southern Blotting/métodos , Elementos de DNA Transponíveis , Proteínas de Ligação a DNA/genética , Mutagênese Insercional , Fenótipo , Esporos BacterianosRESUMO
BACKGROUND/AIMS: Although malignant obstruction, itself, is a significant risk factor associated with post-operative mortality, factors affecting mortality in the surgery of malignant obstruction have not been thoroughly studied in the literature. METHODOLOGY: In order to identify independent risk factors which might be associated with an increase in post-operative mortality in patients with malignant biliary obstruction, 24 clinical and laboratory parameters in 52 patients undergoing biliary tract surgery were analyzed retrospectively. RESULTS: Simple regression revealed 24 factors with prognostic significance, but multivariate analysis detected only 3 factors with independent significance in predicting mortality (cholangitis, weight loss of 10 kg or more and operative or post-operative blood transfusion). The presence of 2 of these risk factors identified a group of patients with an 37% mortality rate. CONCLUSIONS: The results of this study show that the presence of pre-operative cholangitis, marked weight loss, and operative and post-operative blood transfusion are associated with high post-operative mortality. The major challenge is the prevention of cholangitis in high-risk patients, improvement of the nutritional status of the patients, and avoidance of unnecessary blood transfusions.
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Neoplasias dos Ductos Biliares/cirurgia , Ductos Biliares Intra-Hepáticos , Colangiocarcinoma/cirurgia , Procedimentos Cirúrgicos do Sistema Digestório/mortalidade , Neoplasias da Vesícula Biliar/cirurgia , Adulto , Idoso , Idoso de 80 Anos ou mais , Ampola Hepatopancreática , Transfusão de Sangue , Colangiopancreatografia Retrógrada Endoscópica , Colangite/complicações , Neoplasias do Ducto Colédoco/cirurgia , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Estado Nutricional , Estudos Retrospectivos , Fatores de Risco , Análise de SobrevidaRESUMO
A total of 259 clinical isolates of nonrepetitive non-typhi salmonellae (NTS) were examined for antibiotic resistance patterns and plasmid content. The antibiotics used were amoxicillin-clavulanic acid (AMC), ampicillin (AM), aztreonam (ATM), carbenicillin (CB), cefixime (CFM), cefotaxime (CTX), cefoxitin (FOX), ceftazidime (CAZ), ceftriaxone (CRO), chloramphenicol (C), ciprofloxacin (CIP), gentamicin (GM), imipenem (IPM), ofloxacin (OFX), tetracycline (TE), trimethoprim-sulfomethoxazole (SXT). Multi-drug resistant (MDR) strains comprised 19.3% of the total isolates (50/259) and almost all were S. typhimurium (49/50). Fifteen different patterns of resistance was observed, AM/CB/C/AMC/TE and AM/CB/C/AMC/SXT/GM/CTX/CRO/CAZ/CFM/ATM being the most frequent patterns. Twenty-eight out of 50 multiresistant isolates were found to contain at least one plasmid (mean five) and the size of the plasmids ranged between 1.7 and 158 kb. Plasmid profiles of multiresistant NTS strains were heterogenous as 21 different profiles were detected in a total of 28 plasmid-bearing isolates. No direct correlation was established between antibiotic resistance patterns and plasmid profiles.
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Resistência Microbiana a Medicamentos , Resistência a Múltiplos Medicamentos , Plasmídeos/genética , Salmonella/genética , Antibacterianos/farmacologia , Humanos , Salmonella/efeitos dos fármacos , Salmonella/patogenicidade , Infecções por Salmonella/epidemiologia , Turquia/epidemiologiaRESUMO
The effects of truncal vagotomy and proximal gastric vagotomy on bacterial translocation in rats were investigated in this experiment. The rats were divided into three groups. Only esophageal and gastric manipulations were performed in the control group (Group I). The anterior and posterior vagi were found and 0.5- to 1-cm pieces were taken out in the truncal vagotomy + pyloric dilatation group. In addition, pyloric dilatation was performed using a Fogarty catheter (Group II). The branches of the vagi, which lead to the rumen and corpus, were first tied with 5/O silk and then resected in the proximal gastric vagotomy group (Group III). All animals were sacrificed on the 7th day. Qualitative and quantitative tissue cultures of cecum, liver, spleen, mesenteric lymph node, and blood from vena cava were taken and a tissue sample from the ileum was obtained for histopathological examination with light microscopy. At the end of microbiologic study, the bacterial concentration on the cecal wall was 10.68 x 10(8) in the truncal vagotomy group, while it was 0.53 x 10(8) in the proximal gastric vagotomy group. Bacterial translocation was observed more in vagotomy groups than in control groups on the mesenteric lymph node, liver, and spleen. Bacterial translocation was greater in the truncal vagotomy group than in the proximal gastric vagotomy group (P < 0.05). Bacterial translocation was observed mostly in the liver, spleen, and mesenteric lymph node in the proximal gastric vagotomy group. No microorganisms could be cultured on systemic blood cultures. Cultures were positive only for one rat in the proximal gastric vagotomy group and for two rats in the truncal vagotomy group. At the end of histopathologic examination, when histopathologic parameters given for each rat were calculated, they were 5.44 +/- 2.12 in the truncal vagotomy group and 4.77 +/- 2.12 the in proximal gastric vagotomy group. The difference between these two groups was statistically significant (P < 0.05). Thus, there was damage to the intestinal wall in vagotomy groups, and it was greater in the truncal vagotomy group than in the proximal gastric vagotomy group. It was observed that bacterial translocation occurs after vagotomy, that this translocation occurs more after truncal vagotomy than after proximal gastric vagotomy, and that the translocation that occurred after vagotomies was not effective enough to create bacteremia.
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Sistema Digestório/microbiologia , Vagotomia , Animais , Fenômenos Fisiológicos Bacterianos , Linfonodos/microbiologia , Masculino , Movimento , Ratos , Ratos WistarRESUMO
Through preliminary plate tests, Kluyveromyces marxianus was found to be much more resistant to toxic heavy metals compared to a CUP1R strain of Saccharomyces cerevisiae. Specific growth rate and maximum dry weights affected by increasing metal concentrations were determined to obtain precise patterns of resistance. Metal biosorption was also monitored during the course of growth in synthetic media containing respective metals at 0.5 mM final concentration. Although Zn- and Co-binding was negligible, as much as 90% of silver, 60% of copper, and 65% of cadmium were found to be absorbed by the end of active growth. Analysis of the protein profiles of S. cerevisiae and K. marxianus on metal exposure suggested constitutive production of metallothionein in K. marxianus. Furthermore, a smaller protein synthesized by K. marxianus on induction by silver or cadmium accounts for the high resistance of the organism to these metals.
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Kluyveromyces/efeitos dos fármacos , Metais/farmacologia , Resistência a Medicamentos , Eletroforese em Gel de Poliacrilamida , Proteínas Fúngicas/análise , Kluyveromyces/química , Kluyveromyces/metabolismo , Metais/metabolismo , Saccharomyces cerevisiae/efeitos dos fármacosRESUMO
In kinetic studies of the folding of bovine carbonic anhydrase from disorganized to native structure, an azosulfonamide, 2-(4-sulfomylphenylazo)-7-acetamido-1-hydroxynaphthalene-3,6-disulfonate (I), has been used as a probe to follow the dynamics of formation of the active site region. The probe is a specific inhibitor of the native enzyme that binds in the active site crevice. The experiments, with previous data (Yazgan, A., and Henkens, R. W. (1972), Biochemistry 11, 1314), show that a tight binding site for I forms at an intermediate stage in the folding process. A subsequent conformational change perturbs the visible absorption and circular dichroism of bound I and could result in even tighter binding. The subsequent change completes formation of the active site. This is shown by results from separate experiments on the kinetics of recovery of activity (p-nitrophenyl acetate as substrate). Similar probe methods could be used with other proteins and enzymes to study the kinetics and mechanism of regeneration of specific sites--for example, the active site.