Articular cartilage volume in the knee: semiautomated determination from three-dimensional reformations of MR images

PURPOSE: To determine the accuracy of semiautomated quantification of articular cartilage volume from three-dimensional (3D) reformations of magnetic resonance (MR) images. MATERIALS AND METHODS: Sagittal, fat-suppressed, 3D, spoiled gradient-recalled-echo MR imaging of two bovine and two human cadaver knees was performed. Articular cartilage volume was calculated from 3D reformations of the MR images by using a semiautomated program written at the authors' institution. Calculated volumes were compared with directly measured volumes of the surgically removed articular cartilage. RESULTS: The percentage of error of the MR imaging-determined volumes was 6.53% +/- 4.75 (mean +/- standard deviation). A strong correlation between the two sets of observations was shown (r=.997). Linear regression showed the calculated volumes to be highly accurate (slope=1.002, P>.25). Repeated reformations yielded volumes that were reproducible (mean absolute error, 0.013 mL +/- 0.019) and not significantly different from the measured volume (P>.10). CONCLUSION: Semiautomated quantification of knee articular cartilage from MR images yields highly accurate cartilage volumes.     

Production of human normal adult and fetal hemoglobins in Escherichia coli

A hemoglobin expression system in Escherichia coli is described. In order to produce authentic human hemoglobin, we need to co-express both methionine aminopeptidase and globin genes under the control of a strong promoter. We have constructed three plasmids, pHE2, pHE4 and pHE7, for the expression of human normal adult hemoglobin and a plasmid, pHE9, for the expression of human fetal hemoglobin, in high yields. The globin genes can be derived from either synthetic genes or human globin cDNAs. The extra amino-terminal methionine residues of the expressed globins can be removed by the co-expressed methionine aminopeptidase. The heme is inserted correctly into the expressed alpha- globin from our expression plasmids. A fraction (approximately 25%) of the heme is not inserted correctly into the expressed beta- or gamma- globin. However, the incorrectly inserted hemes can be converted into the correct conformation by carrying out a simple oxidation-reduction process on the purified hemoglobin molecule. We have investigated the functional properties of the expressed hemoglobins by measuring their oxygen-binding properties and their structural features by obtaining their 1H-NMR spectra. Our results show that authentic human normal adult and fetal hemoglobins can be produced from our expression plasmids in E. coli and in high yields. Our expression system allows us to design and to produce any recombinant hemoglobins needed for our research on the structure-function relationship in hemoglobin.      

Structural and functional analogy between pneumolysin and proaerolysin

Pneumolysin and proaerolysin are bacterial toxins that form pores in host cells by oligomerization. We propose that they may have similar structures despite a poor sequence identity. The crystal structure of proaerolysin reveals a protein composed of four domains, arranged in the shape of an elongated comma. Electron microscopy of the pneumolysin monomer shows a similar arrangement of domains. The sequence of pneumolysin recognizes the template of proaerolysin from a library of protein folds. A three-dimensional model of pneumolysin has been constructed by the comparative approach using the structure of proaerolysin. This model, together with results on the activity of site- specific mutants and the positions of antigenic sites, has been used to propose functional roles of individual domains.      

Development and characterization of a purified diet to identify obesity-susceptible and resistant rat populations

A purified moderately high fat diet has been developed to examine diet-induced obesity in rats. Male Sprague-Dawley rats were fed this or an AIN-76A diet for 15 wk and energy metabolism indices were monitored. Food intake, body weight and water balance indices were recorded on a weekly or daily basis. Over the 15-wk period, rats fed the experimental diet diverged into two groups differing in the rate of body weight gain. Animals were labeled as "gainers" or "resisters" depending on their susceptibility to obesity. Following the dietary period, rats were decapitated and trunk blood was collected for glucose and insulin measurements. Gainers consumed slightly more energy than resisters over the experimental period (P < 0.05), but due to greater fecal energy loss, absorbed energy did not differ. Hence gainers became obese without significantly altered energy retention. Urinary creatinine, urea nitrogen and water balance were not different between the groups and consequently could not explain body weight differences. Further, gainers had significantly greater plasma glucose concentration than controls, indicating a potential for these animals to become diabetic. Results suggest metabolic differences must account for the divergence in weight gain observed in the two groups. The dietary model characterized in this study should provide a useful tool to study diet-induced obesity and to determine its underlying mechanism.     

Observer agreement on interpreting colposcopic images of CIN

The purpose of this work was to study intraobserver and interobserver variation in the interpretation of colposcopic images of cervical intraepithelial neoplasia (CIN). Twenty-three experienced colposcopists were asked to assess colposcopic images presented on slides and to select the biopsy site. Eleven cases were independently interpreted twice with an interval of 2-3 months by all observers. No information about the cytological classification was available. In each case the "majority assessment" was considered as the standard, being "no CIN" in 2 cases, CIN I in 4 cases, CIN II in 3 cases, and CIN III in 2 cases. Intraobserver concordance was 66.7%, the kappa value was 0.54. Interobserver agreement was found to be 52.4 and 51.0% in the first and second sessions, respectively, while the mean kappa values were 0.41 and 0.33, respectively. In selecting the site for biopsy, 77.4% of all observers agreed while the same site was selected in 85.3% of cases by the individual colposcopist in the two sessions. Overall, CIN I and II interpretations revealed lower levels of agreement than no CIN or CIN III interpretations. It is concluded that observer variability in interpreting colposcopic images and selecting the site for biopsy is in the same range as observer variation in other subjective diagnostic tests such as cytology and histopathology. This variation should be taken into account in the colposcopical management of patients with abnormal cytology.     

Desflurane-mediated sympathetic activation occurs in humans despite preventing hypotension and baroreceptor unloading

BACKGROUND: Increasing concentrations of desflurane result in progressive decreases in blood pressure (BP) and, unlike other currently marketed, potent volatile anesthetics, heightened sympathetic nervous system activity. This study aimed to determine whether baroreflex mechanisms are involved in desflurane-mediated sympathetic excitation. METHODS: Healthy volunteers were anesthetized with desflurane (n = 8) or isoflurane (n = 9). Heart rate (HR; measured by electrocardiograph), blood pressure (BP; measured by arterial catheter), and efferent sympathetic nerve activity (SNA; obtained from percutaneous recordings from the peroneal nerve) were monitored. Baroreflex sensitivity was evaluated at baseline while volunteers were conscious and during 0.5, 1, and 1.5 minimum alveolar concentration (MAC) anesthesia via bolus injections of nitroprusside (100 microg) and phenylephrine (150 microg) to decrease and increase BP. To prevent the BP decline with increasing depths of anesthesia, phenylephrine was infused to maintain mean BP at the 0.5 MAC level. RESULTS: The HR, BP, and SNA were similar between the groups at the conscious baseline measurement. Efferent SNA did not change during higher MAC of isoflurane, but it increased progressively as desflurane concentrations were increased beyond 0.5 MAC, despite maintaining BP at the 0.5 MAC value with phenylephrine infusions (P < 0.05). Cardiac baroslopes (based on changes in HR) were progressively and similarly decreased with increasing concentrations of isoflurane and desflurane (P < 0.05). Sympathetic baroslopes (based on SNA) decreased with increasing isoflurane concentrations but were maintained with increasing concentrations of desflurane; the response was significantly different between groups. CONCLUSIONS: The increase in basal levels of SNA with increasing concentrations of desflurane persisted despite "fixing" BP and thus is probably not due to hypotension and unloading of the baroreceptors. Further, the preservation of reflex increases in SNA to nitroprusside during desflurane indicates that desflurane preserves one component of the baroreflex in humans when BP is "fixed."     

Nutrition support for patients after cardiopulmonary bypass: required modifications of the TPN solution

Background electrolyte (BGE) systems with two coions are frequently used in capillary zone electrophoresis (CZE), especially in cases where indirect optical detection is employed. This study investigates the behavior of analytes, which possess mobilities intermediate to those of the BGE coions used. Besides the expected behavior, where the analytes provide either tailing or fronting zones, unusual behavior with extraordinary zone broadening is also observed in some cases. The explanation for this effect is that binary BGE systems involve, as a physico-chemical rule, a region where the analytes are forced by one coion to give tailing zones and simultaneously by the other coion to give fronting zones. The result of this "schizophrenic" situation is extraordinary zone broadening and deterioration of the detection record. A series of experiments is presented showing in a telling way the electromigration behavior of the discussed type of zones as well as the ways to remedy the deterioration of the peak shape by a mere slight changing of the quantitative composition of the BGE used.     

Resting respiratory tract dendritic cells preferentially stimulate T helper cell type 2 (Th2) responses and require obligatory cytokine signals for induction of Th1 immunity

Consistent with their role in host defense, mature dendritic cells (DCs) from central lymphoid organs preferentially prime for T helper cell type 1 (Th1)-polarized immunity. However, the "default" T helper response at mucosal surfaces demonstrates Th2 polarity, which is reflected in the cytokine profiles of activated T cells from mucosal lymph nodes. This study on rat respiratory tract DCs (RTDCs) provides an explanation for this paradox. We demonstrate that freshly isolated RTDCs are functionally immature as defined in vitro, being surface major histocompatibility complex (MHC) II lo, endocytosishi, and mixed lymphocyte reactionlo, and these cells produce mRNA encoding interleukin (IL)-10. After ovalbumin (OVA)-pulsing and adoptive transfer, freshly isolated RTDCs preferentially stimulated Th2-dependent OVA-specific immunoglobulin (Ig)G1 responses, and antigen-stimulated splenocytes from recipient animals produced IL-4 in vitro. However, preculture with granulocyte/macrophage colony stimulating factor increased their in vivo IgG priming capacity by 2-3 logs, inducing production of both Th1- and Th2-dependent IgG subclasses and high levels of IFN-gamma by antigen-stimulated splenocytes. Associated phenotypic changes included upregulation of surface MHC II and B7 expression and IL-12 p35 mRNA, and downregulation of endocytosis, MHC II processing- associated genes, and IL-10 mRNA expression. Full expression of IL-12 p40 required additional signals, such as tumor necrosis factor alpha or CD40 ligand. These results suggest that the observed Th2 polarity of the resting mucosal immune system may be an inherent property of the resident DC population, and furthermore that mobilization of Th1 immunity relies absolutely on the provision of appropriate microenvironmental costimuli.     

The primary aortoenteric fistula in The Netherlands--the unpublished cases

OBJECTIVE: Primary aortoenteric fistula is a rare disorder of which only four patients have been reported in the Dutch literature so far. The objective of our study was to obtain more realistic figures on the incidence of this condition, with data on the clinical presentation, diagnostic procedures, treatment and results in a group of patients not previously reported as "case histories". METHODS: A questionnaire was sent to all surgical clinics in The Netherlands. Out of 180 questionnaires, 102 have been returned reporting 27 patients to which data of eight others treated in our own institution were added. RESULTS: In all but one of these 29 patients the fistula was caused by an atherosclerotic aneurysm, the one exception being caused by an ingested cocktail pin. Gastrointestinal haemorrhage was the predominant symptom, being present in 28 of the patients, while the complete triad of haemorrhage, pain and a pulsating mass was found in only eight patients. Twenty-seven patients were treated with an in situ graft of which 14 are doing well at long term follow-up. CONCLUSIONS: Primary aortoenteric fistula is far more common than one would expect from the number of patients reported in literature. A high index of suspicion based on a complete physical examination remains the key to a correct diagnosis. Direct closure of the intestine and in situ grafting of the aorta is the treatment of first choice.