Deuterium nuclear spin relaxation in biological tissues

The deuterium nuclear spin relaxation times have been measured in tissues taken from rats given 20% deuterium oxide in their drinking water. The spin-lattice and spin-spin relaxation times were measured at 13.7 MHz by the inversion-recovery and Carr-Purcell-Meiboom-Gill FT methods, respectively. The reciprocals of the spin-lattice (T1) relaxation times were found to correlate well with those of protons in similar nondeuteriated tissues at a similar frequency (13.6 MHz) measured in a separate study. A least-squares analysis of the data yields (1/T1)H = (0.991)(1/T1)D - 3.48 for five tissues (standard deviations of 0.097 for the slope and 0.383 for the intercept with a correlation coefficient of 0.986). Implications with respect to relaxation mechanisms are discussed.     

Can people hear the pitch change on a variable-pitch pulse oximeter?

The introduction of the variable-pitch feature on pulse oximeters in 1983 by the Nellcor Corporation (Hayward, CA) allowed users to rapidly detect changes in oxygen saturation by listening for changes in the pitch of the tones emitted by the pulse oximeter. A few individuals have reported that they have been unable to detect a change in pitch when oxygen saturation changes. To these individuals, the variable-pitch feature of these pulse oximeters has not been beneficial. Using the pitches from one manufacturer of oximeters, we created a computer program to simulate the pitches that accompanied various oxygen saturations. The pitches were recorded onto a tape player and played for 75 volunteer subjects unfamiliar with the pitches of a variable-pitch pulse oximeter. Of our sample, 67% were able to detect a single change in pitch corresponding to a 1% fall in oxygen saturation, and 11% of the population could not detect a change in pitch until there was a change in pitch with every beat. We suggested four alternative designs that may prove beneficial to this group of individuals.     

Early developmental 2,3,7,8-tetrachlorodibenzo-p-dioxin exposure decreases chick embryo heart chronotropic response to isoproterenol but not to agents affecting signals downstream of the beta-adrenergic receptor.

2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) causes cardiovascular toxicity in laboratory animals, including alteration in several processes in which beta-adrenergic receptor (beta-AR) signaling plays important roles. Thus, our laboratory investigated the effects of TCDD on beta-AR expression and signal transduction. Fertile chicken eggs were injected with vehicle (corn oil), 0.24 or 0.3 pmol TCDD/g egg on incubation day 0 (D0) or D5. On D10, heart function was assessed by ECG in ovo. Exposure to TCDD increased the incidence of arrhythmias and decreased the positive chronotropic responsiveness of the heart to isoproterenol. The reduced beta-AR responsiveness was, in part, independent of any overt morphological changes in the heart as chick embryos exposed to TCDD on D5 displayed an intermediate responsiveness to beta-AR agonist in the absence of the dilated cardiomyopathy observed in chick embryos exposed to TCDD on D0. TCDD did not decrease the chronotropic response of the heart to agents that stimulate signals downstream of the beta-AR. In fact, TCDD-exposed embryos were more sensitive than controls to forskolin, increasing heart rates (HR) 21.8 +/- 3.5 beats per min (bpm) above baseline versus control values at 6.3 +/- 2.7 bpm above baseline. TCDD exposure also augmented the negative chronotropic response of the heart to verapamil, decreasing HR -23.2 +/- 7.4 bpm relative to baseline versus control embryos at -12.7 +/- 5.9 bpm below baseline. Finally, the mean cardiac beta1-AR mRNA expression in D10 embryos was not significantly altered by exposure to TCDD on D0. These findings establish that a functional end point of the developing chick heart is sensitive to TCDD exposure and that the TCDD-induced reduction in beta-AR responsiveness may result from alterations in signal transduction upstream of adenylyl cyclase.     

Cell proliferation in adult hippocampus is decreased by inescapable stress: reversal by fluoxetine treatment.

Adult hippocampal neurogenesis has been demonstrated in several species and is regulated by both environmental and pharmacological stimuli. The present study seeks to determine whether hippocampal proliferation and neurogenesis are altered in adult animals exposed to inescapable shock (IS) in the learned helplessness model of depression. We report that exposure to avoidance testing, regardless of pre-exposure to IS, decreases cell proliferation in the hippocampus, extending previous studies demonstrating downregulation of neurogenesis by exposure to acute stressors. In addition, when the analysis was conducted 9 days after exposure to IS we observed a significant decrease in cell proliferation compared to nonshocked animals. Administration of fluoxetine, a serotonin selective reuptake inhibitor, from days 2-8 blocked the downregulation of cell proliferation resulting from IS. Fluoxetine treatment also reversed the deficit in escape latency observed in animals exposed to IS. Finally, at the 9 day time point, there was no significant difference in blood levels of corticosterone between nonshocked and IS exposed animals, indicating that the decreased cell proliferation that is observed is not due to increased levels of this adrenal steroid. These findings demonstrate that exposure to IS, which results in a state of behavioral despair, decreases hippocampal cell proliferation and that this effect can be reversed by fluoxetine treatment.     

Recent trends in early outcome of adult patients after heart transplantation: a single-institution review of 251 transplants using standard donor organs.

Older age, prior transplantation, pulmonary hypertension, and mechanical support are commonly seen in current potential cardiac transplant recipients. Transplants in 436 consecutive adult patients from 1994 to 1999 were reviewed. There were 251 using standard donors in 243 patients (age range 18-69 years). To emphasize recipient risk, 185 patients who received a nonstandard donor were excluded from analysis. The indications for transplant were ischemic heart disease (n = 123, 47%), dilated cardiomyopathy (n = 82, 32%), and others (n=56, 21%). One hundred and forty-nine (57%) recipients were listed as status I; 5 and 6% were supported with an intra-aortic balloon and an assist device, respectively. The 30-d survival and survival to discharge were 94.7 and 92.7%, respectively; 1-year survival was 89.1%. Causes of early death were graft failure (n = 6), infection (n = 4), stroke (n = 4), multiorgan failure (n = 3) and rejection (n = 2). Predictors were balloon pump use alone (OR= 11.4, p =0.002), pulmonary vascular resistance > 4 Wood units (OR = 5.7, p = 0.007), pretransplant creatinine > 2.0 mg/dL (OR = 6.9, p = 0.004) and female donor (OR = 8.3, p = 0.002). Recipient age and previous surgery did not affect short-term survival. Heart transplantation in the current era consistently offers excellent early and 1-year survival for well-selected recipients receiving standard donors. Early mortality tends to reflect graft failure while hospital mortality may be more indicative of recipient selection.     

Necrosectomy and postoperative local lavage in patients with necrotizing pancreatitis: Results of a prospective clinical trial

Seventy-four patients with necrotizing pancreatitis were included in a prospective clinical trial of a surgical management protocol comprising necrosectomy and postoperative local lavage of the lesser sac and of the necrosis cavity. Fifty-eight patients showed preoperative organ failures such as pulmonary dysfunctions (57%), renal dysfunctions (37%), shock (12%), and sepsis (26%) in spite of intensive care treatment. The median value of the early prognostic signs was 4.5 points. Intraoperatively, 62% of the patients revealed extensive intrapancreatic parenchymal necrosis, 69% had extrapancreatic necrosis, and 39% showed bacterial contamination of the necrotic material. Following the necrosectomy, postoperative local lavage was performed for an average period of 25 days with 7 liters (median) of lavage fluid per 24 hours. In each of 18 studied patients, a considerable release of immunoreactive trypsin was demonstrated and, in each of 20 studied patients, a high concentration of immunoreactive phospholipase A₂ was demonstrated in the lavage fluid up to the 12th/14th postoperative day. The intensive care period averaged 6 1/2 days, the hospital stay averaged 54 days. The hospital mortality rate was 8.1%. It is concluded that restricted necrosectomy and postoperative local lavage treatment correspond in particular to the pathomorphologic conditions and to the local release of biologically active compounds such as bacteria, endotoxin, trypsin, and phospholipase A₂ in patients with necrotizing pancreatitis.

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Resumen Setenta y cuatro pacientes con pancreatitis necrotizante fueron incluídos en un ensayo clínico prospectivo aplicando un protocolo de manejo quirÚrgico que comprende necrosectomía y lavado peritoneal postoperatorio de la transcavidad de los epiplones y de la cavidad necrótica. Cincuenta y ocho pacientes exhibierion fallas orgánicas postoperatorias tales como disfunción pulmonar (57%), disfunción renal (37%), shock (12%), y sepsis (26%) a pesar de cuidado intensivo. El valor promedio de los signos précoces pronóstico (Ranson), con exclusión de la retención de líquido fue de 4.5 puntos. Los hallazgos intraoperatorios revelaron necrosis pancreática extensa en 62% de los pacientes, necrosis extrapancreática en 69%, y contaminación bacteriana del material necrótico en 39%. Realizada la necrosectomía se instauró lavado peritoneal postoperatorio por un período promedio de 25 días con 7 litros (promedio) de líquido por cada 24 horas. En cada uno de los 18 pacientes estudiados se demostró liberación considerable de tripsina inmunorreactiva, así como una elevada concentración de fosfolipasa A₂ inmunorreactiva, en el líquido de lavado hasta el 12/14 días postoperatorios. El período de cuidado intensivo fue de 6 1/2 días, y la hospitalización de 54 días en promedio. La mortalidad hospitalaria fue de 8.1%. En conclusión, se plantea que el tratamiento mediante la necrosectomía restringida y el lavado peritoneal local postoperatorio está indicado en pacientes con las condiciones patomorfológicas de pancreatitis necrotizante que resultan en la liberación local de compuestos biológicamente activos tales como bacterias, endotoxina, tripsina, y fosfolipasa A₂. Serán necesarios ulteriores estudios clínicos controlados para confirmar los resultados favorables que hemos obtenido con la necrosectomía y el lavado peritoneal postoperatorio en pacientes con pancreatitis necrotizante y extensa e infectada necrosis pancreática.

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Résumé Un essai prospectif d'une méthode de traitement chirurgical consistant en nécrosectomie associée au lavage de l'arrière cavité des épiploons et de la cavité nécrotique a concerné 74 malades présentant une pancréatite nécrotique. Malgrè le traitement intensif 58 d'entre eux ont accusé des complications telles que troubles pulmonaires (57%), rénaux (37%), choc (12%), et infection (26%). La valeur moyenne des signes de pronostic précoce fut de 4.5 points. A l'intervention 62% des opérés présentaient une nécrose pancréatique étendue, 69% des opérés une nécrose extra-pancréatique, 39% une surinfection du tissu pancréatique. Après l'exèrése de la nécrose le lavage fut pratiqué quotidiennement avec en moyenne 7 litres de liquide pendant une période de 25 jours. Chez 18 malades fut constaté une libération importante de trypsine immunoactive et chez 20 malades un taux élevé de phospholipase cA dans le liquide de lavage pendant 12/14 jours après l'intervention. La durée des soins intensifs fut en moyenne de 6.5 jours et celle de l'hospitalisation de 54 jours. Le taux de mortalité opératoire fut de 8.1%. On peut conclure de ces faits que la nécrosectomie limitée, associée au lavage local constitue un traitement adapté aux lésions et à la libération locale d'éléments biologiques pathologiques: bactérie, endotoxine, trypsine, et phospholipase A au cours de la pancréatite nécrotique.

     

Olfactomotor activity during imagery mimics that during perception

Neural representations created in the absence of external sensory stimuli are referred to as imagery, and such representations may be augmented by reenactment of sensorimotor processes. We measured nasal airflow in human subjects while they imagined sights, sounds and smells, and only during olfactory imagery did subjects spontaneously enact the motor component of olfaction--that is, they sniffed. Moreover, as in perception, imagery of pleasant odors involved larger sniffs than imagery of unpleasant odors, suggesting that the act of sniffing has a functional role in creating of olfactory percepts.     

Mosaicism for an FMR1 gene deletion in a fragile X female

Most cases of fragile X syndrome result from expansion of CGG repeats in the FMR1 gene; deletions and point mutations of FMR1 are much less common. Mosaicism for an FMR1 full mutation with a deletion or with a normal allele has been reported in fragile X males. Here we report on a fragile X female who is mosaic for an FMR1 full mutation and an intragenic deletion. The patient is a 4-year-old girl with developmental delay, autistic-like behaviors, and significant speech and language abnormalities. Southern blotting demonstrated the presence of a methylated full mutation, a normal allele in methylated and unmethylated forms, and an additional fragment smaller than the normal methylated allele. This result indicates that the patient is mosaic for a full mutation and a deletion, in the presence of a normal allele. By DNA sequence analysis, we mapped the 5' breakpoint 63/65 bp upstream from the CGG repeat region and the 3' breakpoint 86/88 bp downstream of the CGG repeats within the FMR1 gene. The deletion removed 210 bp, including the entire CGG repeat region. The full mutation was inherited from a premutation in the patient's mother. The deletion, which remained methylated at the Eag I and Nru I sites, was probably derived from the full mutation allele. Mosaicism of this type is rare in females with a fragile X mutation but should be kept in mind in the interpretation of Southern blots.     

An efficient method for cloning human autoantigen-specific T cells

T-cell clones are valuable tools for investigating T-cell specificity in infectious, autoimmune and malignant diseases. T cells specific for clinically-relevant autoantigens are difficult to clone using traditional methods. Here we describe an efficient method for cloning human autoantigen-specific CD4+ T cells pre-labelled with CFSE. Proliferating, antigen-responsive CD4+ cells were identified flow cytometrically by their reduction in CFSE staining and single cells were sorted into separate wells. The conditions (cytokines, mitogens and tissue culture plates) for raising T-cell clones were optimised. Media supplemented with IL-2+IL-4 supported growth of the largest number of antigen-specific clones. Three mitogens, PHA, anti-CD3 and anti-CD3+anti-CD28, each stimulated the growth of similar numbers of antigen-specific clones. Cloning efficiency was similar in flat- and round-bottom plates. Based on these findings, IL-2+IL-4, anti-CD3 and round-bottom plates were used to clone FACS-sorted autoantigen-specific CFSE-labelled CD4+ T cells. Sixty proinsulin- and 47 glutamic acid decarboxylase-specific clones were obtained from six and two donors, respectively. In conclusion, the CFSE-based method is ideal for cloning rare, autoantigen-specific, human CD4+ T cells.