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1.
Knee Surg Sports Traumatol Arthrosc ; 30(6): 1976-1989, 2022 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-35072757

RESUMEN

PURPOSE: The purpose of this study was to determine and compare the percentage of completely healed meniscal tears after arthroscopic repair combined with anterior cruciate ligament reconstruction (ACLR) for the different vascular zones of the meniscus. METHODS: PubMed, Embase, Web of Science, Cochrane library and Emcare were searched on 19 May 2020 for articles reporting healing rates after arthroscopic meniscal repair with concomitant ACLR for the different meniscal vascular zones as assessed by second-look arthroscopy. Data on meniscal tears were extracted as located in zones 1, 2 or 3, according to the Cooper classification. Studies were graded in quality using a modified Newcastle-Ottawa Scale. Pooled analyses were performed utilizing a random-effects model. Meta-analyses were performed using R version 3.6.2 and SPSS statistical software version 25.0. The study was registered with PROSPERO (ID:CRD42020176175). RESULTS: Ten observational cohort studies met the inclusion criteria, accounting for 758 meniscal tear repairs in total. The pooled overall proportion of healing was 78% (95% CI 72-84%). The mean weighted proportion of healing was 83% (95% CI 76-90%) for studies (n = 10) reporting zone 1 tears and 69% (95% CI 59-79%) for studies (n = 9) reporting zone 2 tears. No study reported healing rates for zone 3 tears. The pooled overall odds ratio was 2.5 (95% CI 1.00-6.02), indicating zone 1 tears as 2.5 times more likely to heal than zone 2 tears. CONCLUSION: This study demonstrates that meniscal tears localized in vascular zone 1 were more likely to heal than those in zone 2. LEVEL OF EVIDENCE: IV.


Asunto(s)
Lesiones del Ligamento Cruzado Anterior , Reconstrucción del Ligamento Cruzado Anterior , Enfermedades de los Cartílagos , Traumatismos de la Rodilla , Lesiones de Menisco Tibial , Lesiones del Ligamento Cruzado Anterior/cirugía , Artroscopía , Enfermedades de los Cartílagos/cirugía , Humanos , Traumatismos de la Rodilla/cirugía , Meniscos Tibiales/cirugía , Segunda Cirugía , Lesiones de Menisco Tibial/cirugía
2.
Acta Psychiatr Scand ; 135(1): 78-86, 2017 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-27800603

RESUMEN

OBJECTIVE: To estimate the association between hippocampal and total brain volume and the course of depressive symptoms over eight years of follow-up in patients with a history of vascular disease. METHOD: Within the SMART-Medea study, 636 participants (62 ± 10 years) had a 1.5-tesla brain MRI obtaining hippocampal and total brain volumes. Depressive symptoms were assessed with the Patient Health Questionnaire-9 biannually during eight-year follow-up. Generalized estimating equation models with robust standard errors were used to assess the associations of hippocampal and total brain volumes with depressive symptoms during follow-up adjusting for age, sex, education, and intracranial volume. An interaction term between volume and time (6-month intervals) was included to examine whether the course of depressive symptoms differed according to hippocampal and total brain volume. RESULTS: The mean PHQ-9 score was 2.8 ± 3.5. Smaller hippocampal volumes were associated with an increasing course of depressive symptom levels, while larger volumes were associated with decreasing levels (P-value interaction = 0.07). Smaller total brain volume was associated with consistently higher levels of depressive symptoms, but not with change in course of depressive symptoms (P-value interaction = 0.45). CONCLUSION: Smaller hippocampal volume but not total brain volume is associated with poorer course of depressive symptoms over eight years of follow-up.


Asunto(s)
Depresión/diagnóstico por imagen , Hipocampo/diagnóstico por imagen , Imagen por Resonancia Magnética/métodos , Anciano , Encéfalo/diagnóstico por imagen , Femenino , Estudios de Seguimiento , Humanos , Masculino , Persona de Mediana Edad , Neuroimagen/métodos , Escalas de Valoración Psiquiátrica
3.
Psychol Med ; 45(6): 1219-28, 2015 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-25273347

RESUMEN

BACKGROUND: Psychosocial stress has been related to changes in the nervous system, with both adaptive and maladaptive consequences. The aim of this study was to examine the relationship of negative events experienced throughout the entire lifespan and hippocampal and amygdala volumes in older adults. METHOD: In 466 non-demented old adults (age range 60-96 years, 58% female), hippocampal and amygdala volumes were segmented using Freesurfer. Negative life events and the age at which these events occurred were assessed by means of a structured questionnaire. Using generalized linear models, hippocampal and amygdala volumes were estimated with life events as independent variables. The statistical analyses were adjusted for age, gender, intracranial volume, lifestyle factors, cardiovascular risk factors, depressive symptoms, and cognitive functioning. RESULTS: Total number of negative life events and of late-life events, but not of early-life, early-adulthood, or middle-adulthood events, was related to larger amygdala volume. There were interactions of early-life events with age and gender. Participants who reported two or more early-life events had significantly smaller amygdala and hippocampal volumes with increasing age. Furthermore, smaller hippocampal volume was found in men who reported two or more early-life events, but not in women. CONCLUSIONS: These results suggest that the effect of negative life events on the brain depends on the time when the events occurred, with the strongest effects observed during the critical time periods of early and late life.


Asunto(s)
Amígdala del Cerebelo/anatomía & histología , Hipocampo/anatomía & histología , Acontecimientos que Cambian la Vida , Factores de Edad , Anciano , Anciano de 80 o más Años , Amígdala del Cerebelo/patología , Femenino , Hipocampo/patología , Humanos , Masculino , Persona de Mediana Edad , Factores Sexuales
4.
Psychol Med ; 45(16): 3517-26, 2015 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-26204801

RESUMEN

BACKGROUND: Childhood maltreatment (CM) may modify the relationship between major depressive disorder (MDD) and hippocampal volume reduction. To disentangle the impact of MDD and CM on hippocampal volume we investigated the association between MDD and hippocampal volume in persons with and without a history of CM in two independent cohorts. METHOD: We used data of 262 participants from the Netherlands Study of Depression and Anxiety (NESDA) (mean age 37 years, 32% male) and 636 participants from the SMART-Medea study (mean age 61 years, 81% male). In both studies a 12-month diagnosis of MDD and CM were assessed using a diagnostic interview. Hippocampal volume was measured in NESDA using FreeSurfer software on 3-T magnetic resonance (MR) images and in SMART it was manually outlined on 1.5-T MR images. With analysis of covariance adjusted for intracranial volume, age, gender and lifestyle factors we estimated the effects of MDD and CM on hippocampal volume. RESULTS: In both cohorts CM was not significantly associated with hippocampal volume. After pooling the data MDD was associated with smaller hippocampal volume (B = -138.90 mm(3), p = 0.05) and the interaction between MDD and CM reached significance (p = 0.04); in participants with CM, MDD was related to smaller hippocampal volume (NESDA: B = -316.8 mm(3), p = 0.02; SMART: B = -407.6, p = 0.046), but not in participants without CM (p > 0.05). CONCLUSIONS: Our study shows that in two independent cohorts, particularly in individuals with CM, a diagnosis of MDD is related to smaller hippocampal volume. Prospective studies are needed to further determine through which mechanism CM may amplify the relationship between MDD and hippocampal volume.


Asunto(s)
Adultos Sobrevivientes de Eventos Adversos Infantiles/psicología , Trastorno Depresivo Mayor/patología , Hipocampo/patología , Adolescente , Adulto , Anciano , Anciano de 80 o más Años , Estudios de Cohortes , Femenino , Humanos , Modelos Lineales , Imagen por Resonancia Magnética , Masculino , Persona de Mediana Edad , Países Bajos , Tamaño de los Órganos , Encuestas y Cuestionarios , Adulto Joven
5.
Mol Psychiatry ; 17(6): 597-603, 2012 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-21577214

RESUMEN

According to the neurotrophic hypothesis of depression, stress can lead to brain atrophy by modifying brain-derived neurotrophic factor (BDNF) levels. Given that BDNF secretion is affected by a common polymorphism (rs6265, Val66Met), which also is associated with depression, we investigated whether this polymorphism modifies the effect of childhood adversity (CA) on local gray matter (GM) volume in depression-relevant brain regions, using data from two large cohorts of healthy subjects. We included 568 healthy volunteers (aged 18-50 years, 63% female) in our study, for whom complete data were available, with magnetic resonance imaging data at 1.5 Tesla (N=275) or 3 Tesla (N=293). We used a whole brain optimized voxel-based morphometry (VBM) approach assessing genotype-dependent GM differences, with focus on the amygdala, hippocampus and medial prefrontal cortex (PFC; including anterior cingulate cortex (ACC) and orbitomedial PFC). CA was assessed using a validated questionnaire. In both cohorts, we found that BDNF methionine (Met)-allele carriers with a history of CA had significantly less GM in subgenual ACC (P<0.05) compared with Met-allele carriers without CA and Val/Val homozygotes with CA. No differences were found in hippocampus, amygdala and orbitomedial PFC. On the basis of our findings, we conclude that BDNF Met-allele carriers are particularly sensitive to CA. Given the key role of the subgenual ACC in emotion regulation, this finding provides an important mechanistic link between stress and BDNF on one hand and mood impairments on the other hand.


Asunto(s)
Mapeo Encefálico/psicología , Factor Neurotrófico Derivado del Encéfalo/genética , Giro del Cíngulo/patología , Polimorfismo de Nucleótido Simple , Estrés Psicológico/genética , Estrés Psicológico/patología , Adolescente , Adulto , Atrofia/genética , Mapeo Encefálico/métodos , Femenino , Genotipo , Humanos , Imagen por Resonancia Magnética/métodos , Imagen por Resonancia Magnética/psicología , Masculino , Persona de Mediana Edad , Fibras Nerviosas Amielínicas/patología , Autoinforme
6.
Neuroimage ; 61(4): 1043-9, 2012 Jul 16.
Artículo en Inglés | MEDLINE | ID: mdl-22440643

RESUMEN

Animal and human autopsy studies suggest that subfields of the hippocampal formation are differentially affected by neuropsychiatric diseases. Therefore, subfield volumes may be more sensitive to effects of disease processes. The few human studies that segmented subfields of the hippocampal formation in vivo either assessed the subfields only in the body of the hippocampus, assessed only three subfields, or did not take the differential angulation of the head of the hippocampus into account. We developed a protocol using 7 Tesla MRI with isotropic voxels to reliably delineate the entorhinal cortex (ERC), subiculum (SUB), CA1, CA2, CA3, dentate gyrus (DG)&CA4 along the full-length of the hippocampus. Fourteen subjects (aged 54-74 years, 2 men and 12 women) were scanned with a 3D turbo spin echo (TSE) sequence with isotropic voxels of 0.7 × 0.7 × 0.7 mm(3) on a 7 T MRI whole body scanner. Based on previous protocols and extensive anatomic atlases, a new protocol for segmentation of subfields of the hippocampal formation was formulated. ERC, SUB, CA1, CA2, CA3 and DG&CA4 were manually segmented twice by one rater from coronal MR images. Good-to-excellent consistency was found for all subfields (Intraclass Correlation Coefficient's (ICC) varying from 0.74 to 0.98). Accuracy as measured with the Dice Similarity Index (DSI) was above 0.82 for all subfields, with the exception of the smaller subfield CA3 (0.68-0.70). In conclusion, this study shows that it is possible to delineate the main subfields of the hippocampal formation along its full-length in vivo at 7 T MRI. Our data give evidence that this can be done in a reliable manner. Segmentation of subfields in the full-length of the hippocampus may bolster the study of the etiology neuropsychiatric diseases.


Asunto(s)
Hipocampo/anatomía & histología , Interpretación de Imagen Asistida por Computador/métodos , Imagen por Resonancia Magnética/métodos , Anciano , Femenino , Humanos , Masculino , Persona de Mediana Edad
7.
Psychol Med ; 42(2): 335-43, 2012 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-21740626

RESUMEN

BACKGROUND: Negative memory bias is thought to be one of the main cognitive risk and maintenance factors for depression, but its neural substrates are largely unknown. Here, we studied whether memory bias is related to amygdala and hippocampal volume, two structures that are critical for emotional memory processes and that show consistent volume alterations in depression. METHOD: Structural magnetic resonance imaging (MRI) was carried out in 272 healthy participants (62% female, 18-50 years old). All images were acquired on 1.5 T Siemens MRI scanners. Automatic segmentation of amygdala and hippocampus was performed using the FIRST module of FSL. Negative memory bias was assessed by the self-referent encoding/evaluation test. RESULTS: Negative memory bias was associated with larger amygdala (p=0.042) and smaller hippocampal (p=0.029) volumes. In additional analyses, we found that, compared with the associations found with hippocampus and amygdala volume separately, a stronger association was found between negative memory bias and the ratio of amygdala:hippocampus volume (p=0.021). CONCLUSIONS: In non-depressed subjects we found that larger amygdala and smaller hippocampal volumes are associated with negative memory bias. This suggests that an increased amygdala:hippocampus volume ratio plays a role in cognitive vulnerability often seen in individuals with high risk for depression and that these structural brain differences may pre-date the onset of depression.


Asunto(s)
Afecto/fisiología , Amígdala del Cerebelo/anatomía & histología , Hipocampo/anatomía & histología , Memoria/fisiología , Adolescente , Adulto , Amígdala del Cerebelo/patología , Depresión/patología , Depresión/fisiopatología , Femenino , Hipocampo/patología , Humanos , Imagen por Resonancia Magnética , Masculino , Persona de Mediana Edad , Riesgo , Adulto Joven
9.
Open Forum Infect Dis ; 8(7): ofab298, 2021 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-34258321

RESUMEN

The treatment of staphylococcal prosthetic joint infection (PJI) with debridement, antibiotics, and retention of the implant (DAIR) often results in failure. An important evidence gap concerns the treatment with rifampicin for PJI. A systematic review and meta-analysis were conducted to assess the outcome of staphylococcal hip and/or knee PJI after DAIR, focused on the role of rifampicin. Studies published until September 2, 2020 were included. Success rates were stratified for type of joint and type of micro-organism. Sixty-four studies were included. The pooled risk ratio for rifampicin effectiveness was 1.10 (95% confidence interval, 1.00-1.22). The pooled success rate was 69% for Staphylococcus aureus hip PJI, 54% for S aureus knee PJI, 83% for coagulase-negative staphylococci (CNS) hip PJI, and 73% for CNS knee PJI. Success rates for MRSA PJI (58%) were similar to MSSA PJI (60%). The meta-analysis indicates that rifampicin may only prevent a small fraction of all treatment failures.

10.
Psychol Med ; 40(9): 1569-78, 2010 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-19939325

RESUMEN

BACKGROUND: It has been hypothesized that stressful life events are associated with changes in hypothalamic-pituitary-adrenal (HPA) axis regulation, which increases susceptibility to psychiatric disorders. We investigated the association of early and late life events with HPA axis regulation in older persons. METHOD: Within the Longitudinal Aging Study Amsterdam (LASA) 1055 participants (47% male), aged 63-93 years, collected saliva within 30 min after waking and late in the evening. Early and late life events were assessed during a home interview. The associations between life events and cortisol levels were examined using linear regression and analysis of covariance with adjustments for demographics, cardiovascular risk factors and depressive symptoms. RESULTS: Within our sample, the median morning and evening cortisol levels were 15.0 nmol/l [interdecile range (10-90%): 7.4-27.0 nmol/l] and 2.8 nmol/l (10-90%: 1.5-6.3 nmol/l), respectively. Persons who reported early life events showed lower levels of natural log-transformed morning cortisol [B=-0.10, 95% confidence interval (CI) -0.17 to -0.04] and flattened diurnal variability of cortisol (B=-1.06, 95% CI -2.05 to -0.08). Those reporting two or more late life events showed higher levels of natural log-transformed morning cortisol (B=0.10, 95% CI 0.02-0.18) and higher diurnal variability (B=1.19, 95% CI 0.05-2.33). No associations were found with evening cortisol. CONCLUSIONS: The results of this large population-based study of older persons suggest a differential association of early and late life events with HPA axis regulation; early life events were associated with a relative hypo-secretion of morning cortisol and flattened diurnal variability, while late life events were associated with elevated secretion of morning cortisol and high diurnal variability of cortisol.


Asunto(s)
Envejecimiento/psicología , Hidrocortisona/metabolismo , Acontecimientos que Cambian la Vida , Estrés Psicológico/metabolismo , Anciano , Anciano de 80 o más Años , Ritmo Circadiano , Femenino , Humanos , Sistema Hipotálamo-Hipofisario , Modelos Lineales , Estudios Longitudinales , Masculino , Persona de Mediana Edad , Países Bajos , Sistema Hipófiso-Suprarrenal , Saliva/metabolismo
11.
Transl Psychiatry ; 7(4): e1100, 2017 04 18.
Artículo en Inglés | MEDLINE | ID: mdl-28418400

RESUMEN

The association between telomere length (TL) dynamics on cognitive performance over the life-course is not well understood. This study meta-analyses observational and causal associations between TL and six cognitive traits, with stratifications on APOE genotype, in a Mendelian Randomization (MR) framework. Twelve European cohorts (N=17 052; mean age=59.2±8.8 years) provided results for associations between qPCR-measured TL (T/S-ratio scale) and general cognitive function, mini-mental state exam (MMSE), processing speed by digit symbol substitution test (DSST), visuospatial functioning, memory and executive functioning (STROOP). In addition, a genetic risk score (GRS) for TL including seven known genetic variants for TL was calculated, and used in associations with cognitive traits as outcomes in all cohorts. Observational analyses showed that longer telomeres were associated with better scores on DSST (ß=0.051 per s.d.-increase of TL; 95% confidence interval (CI): 0.024, 0.077; P=0.0002), and MMSE (ß=0.025; 95% CI: 0.002, 0.047; P=0.03), and faster STROOP (ß=-0.053; 95% CI: -0.087, -0.018; P=0.003). Effects for DSST were stronger in APOE ɛ4 non-carriers (ß=0.081; 95% CI: 0.045, 0.117; P=1.0 × 10-5), whereas carriers performed better in STROOP (ß=-0.074; 95% CI: -0.140, -0.009; P=0.03). Causal associations were found for STROOP only (ß=-0.598 per s.d.-increase of TL; 95% CI: -1.125, -0.072; P=0.026), with a larger effect in ɛ4-carriers (ß=-0.699; 95% CI: -1.330, -0.069; P=0.03). Two-sample replication analyses using CHARGE summary statistics showed causal effects between TL and general cognitive function and DSST, but not with STROOP. In conclusion, we suggest causal effects from longer TL on better cognitive performance, where APOE ɛ4-carriers might be at differential risk.


Asunto(s)
Disfunción Cognitiva/genética , Análisis de la Aleatorización Mendeliana , Telómero/genética , Población Blanca/genética , Adulto , Anciano , Apolipoproteína E4/genética , Disfunción Cognitiva/diagnóstico , Estudios de Cohortes , Femenino , Tamización de Portadores Genéticos , Genotipo , Humanos , Masculino , Persona de Mediana Edad , Pruebas Neuropsicológicas/estadística & datos numéricos , Psicometría , Estadística como Asunto
12.
Food Funct ; 4(11): 1700-8, 2013 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-24108199

RESUMEN

Pasta and noodles were enriched with concentrations of broccoli powder (BP) up to 30% (v/v). To ensure the benefits from the broccoli nutrients, their leakage during cooking should be prevented. Such leakage is determined by the microstructure. In a previous study we have shown that the microstructure can change dramatically in such broccoli-enriched products. In this article we investigated the amount of nutrients retained within the product. As a representative of nutrients we have chosen glucosinolates (GLs). Therefore, we have investigated the concentration of these phytochemicals in dried and cooked pasta and noodles. We have found that glucosinolates present in the pasta and noodles increase linearly with the volume fraction of BP up to 20%. At 30% BP the retained amount of GLs was equal to that of 20% BP and did not increase further. Therefore incorporation of 30% BP does not lead to additional health benefits over incorporation of 20% BP. We conclude that the nutritional function of our pasta-like products can be improved by enrichment up to 20% broccoli. This value is much higher than that found in common commercial products (which is a few percent). In this article we also briefly address the sensory acceptability of such products. Up to 20% broccoli the products turned out to remain acceptable. Combining this with our results on texture analysis we conclude that the GLs release, sensory acceptability and textural properties are related via the microstructure.


Asunto(s)
Brassica/química , Aditivos Alimentarios/química , Valor Nutritivo , Gusto , Adulto , Brassica/metabolismo , Culinaria , Femenino , Harina/análisis , Aditivos Alimentarios/metabolismo , Análisis de los Alimentos , Glucosinolatos/análisis , Humanos , Masculino , Adulto Joven
13.
J Insect Physiol ; 59(4): 487-93, 2013 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-23439242

RESUMEN

Varroa destructor in combination with one or more stressors, such as low food availability or chemical exposure, is considered to be one of the main causes for honey bee colony losses. We examined the interactive effect of pollen availability on the protein content and body weight of young bees that emerged with and without V. destructor infestation. With reduced pollen availability, and the coherent reduced nutritional protein, we expected that V. destructor infestation during the pupal stage would have a larger negative effect on bee development than without infestation. Moreover, when raised with ample pollen available after emergence, infested pupae were expected not to be able to compensate for early losses due to V. destructor. We found that both V. destructor infestation and reduced pollen availability reduced body weight, abdominal protein level, and increased the head to abdomen protein ratio. The availability of pollen did indeed not result in compensation for reduced mass and protein content caused by V. destructor infestation in young bees after 1 week of their adult life. Both V. destructor and nutrition are top concerns for those studying honey bee health and this study demonstrates that both have substantial effects on young bees and that ample available pollen cannot compensate for reduced mass and protein content caused by V. destructor parasitism.


Asunto(s)
Abejas/fisiología , Abejas/parasitología , Polen , Varroidae/fisiología , Animales , Abejas/crecimiento & desarrollo , Femenino , Proteínas/metabolismo , Pupa/crecimiento & desarrollo , Pupa/parasitología , Pupa/fisiología
14.
Rev Sci Instrum ; 84(2): 023102, 2013 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-23464190

RESUMEN

In this paper, we report on the design and performance of a new home-built pulsed gas valve, which we refer to as the Nijmegen Pulsed Valve (NPV). The main output characteristics include a short pulse width (as short as 20 µs) combined with operating rates up to 30 Hz. The operation principle of the NPV is based on the Lorentz force created by a pulsed current passing through an aluminum strip located within a magnetic field, which opens the nozzle periodically. The amplitude of displacement of the opening mechanism is sufficient to allow the use of nozzles with up to 1.0 mm diameter. To investigate the performance of the valve, several characterizations were performed with different experimental methods. First, a fast ionization gauge was used to measure the beam intensity of the free jet emanating from the NPV. We compare free jets from the NPV with those from several other pulsed valves in current use in our laboratory. Results showed that a high intensity and short pulse-length beam could be generated by the new valve. Second, the NPV was tested in combination with a skimmer, where resonance enhanced multiphoton ionization combined with velocity map imaging was used to show that the NPV was able to produce a pulsed molecular beam with short pulse duration (~20 µs using 0.1% NO/He at 6 bars) and low rotational temperature (~1 K using 0.5% NO/Ar at 6 bars). Third, a novel two-point pump-probe method was employed which we label double delay scan. This method allows a full kinematic characterization of the molecular beam, including accurate speed ratios at different temporal positions. It was found that the speed ratio was maximum (S = 50 using 0.1% NO/He at 3 bars) at the peak position of the molecular beam and decreased when it was on the leading or falling edge.

15.
Appl Environ Microbiol ; 58(6): 1975-9, 1992 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-1622273

RESUMEN

From Xenorhabdus luminescens XE-87.3 four variants were isolated. One, which produced a red pigment and antibiotics, was luminescent, and could take up dye from culture media, was considered the primary form (XE-red). A pink-pigmented variant (XE-pink) differed from the primary form only in pigmentation and uptake of dye. Of the two other variants, one produced a yellow pigment and fewer antibiotics (XE-yellow), while the other did not produce a pigment or antibiotics (XE-white). Both were less luminescent, did not take up dye, and had small cell and colony sizes. These two variants were very unstable and shifted to the primary form after 3 to 5 days. It was not possible to separate the primary form and the white variant completely; subcultures of one colony always contained a few colonies of the other variant. The white variant was also found in several other X. luminescens strains. DNA fingerprints showed that all four variants are genetically identical and are therefore derivatives of the same parent. Protein patterns revealed a few differences among the four variants. None of the variants could be considered the secondary form. The pathogenicity of the variants decreased in the following order: XE-red, XE-pink, XE-yellow, and XE-white. The mechanism and function of this variability are discussed.


Asunto(s)
Enterobacteriaceae/citología , Animales , Antibacterianos/biosíntesis , Proteínas Bacterianas/aislamiento & purificación , Dermatoglifia del ADN , ADN Bacteriano/genética , Enterobacteriaceae/genética , Enterobacteriaceae/metabolismo , Variación Genética , Luminiscencia , Nematodos/microbiología , Pigmentos Biológicos/biosíntesis , Simbiosis
16.
Appl Environ Microbiol ; 61(1): 284-9, 1995 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-16534911

RESUMEN

In this study antisera against Photorhabdus luminescens strains were prepared for the first time. P. luminescens is a bacterial symbiont of entomopathogenic nematodes belonging to the genus Heterorhabditis. To characterize P. luminescens strains and form variants, we produced polyclonal antisera against P. luminescens PE (obtained from nematode strain NLH-E87.3) and against the primary and secondary forms of P. luminescens PSH (obtained from nematode strain DH-SH1). In double-diffusion tests all form variants of strain PE reacted with the antiserum against the primary form, but each variant produced a different diffusion pattern. The primary and secondary forms of strain PSH were also serologically different. Antiserum 9226 reacted with almost all P. luminescens strains tested, but it reacted differently with each strain in the double-diffusion test, showing that the strains were serologically different. The specificity of the antisera was increased by cross-absorption. After cross-absorption the antiserum against the strain PSH primary or secondary form was specific for that form and did not react with the other form. Using the cross-absorbed antisera in immunofluorescence cell-staining tests, we could distinguish primary and secondary form cells in a mixed strain PSH culture.

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