Identification of vulnerable carotid plaque with CT-based radiomics nomogram

AIM

To develop and validate a radiomics nomogram for identifying high-risk carotid plaques on computed tomography (CT) angiography (CTA).

MATERIALS AND METHODS

A total of 280 patients with symptomatic (n=131) and asymptomatic (n=139) carotid plaques were divided into a training set (n=135), validation set (n=58), and external test set (n=87). Radiomic features were extracted from CTA images. A radiomics model was constructed based on selected features and a radiomics score (rad-score) was calculated. A clinical factor model was constructed by demographics and CT findings. A radiomics nomogram combining independent clinical factors and the rad-score was constructed. The diagnostic performance of three models was evaluated and validated by region of characteristic curves.

RESULTS

Calcification and maximum plaque thickness were the independent clinical factors. Twenty-four features were used to build the radiomics signature. In the validation set, the nomogram (area under the curve [AUC], 0.977; 95% CI, 0.899-0.999) performed better (p=0.017 and p=0.031) than the clinical factor model (AUC, 0.862; 95% CI, 0.746-0.938) and radiomics signature (AUC, 0.944; 95% CI, 0.850-0.987). In external test set, the nomogram (AUC, 0.952; 95% CI, 0.884-0.987) and radiomics signature (AUC, 0.932; 95% CI, 0.857-0.975) showed better discrimination capability (p=0.002 and p=0.037) than clinical factor model (AUC, 0.818; 95% CI, 0.721-0.892).

CONCLUSION

The CT-based nomogram showed satisfactory performance in identification of high-risk plaques in carotid arteries, and it may serve as a potential non-invasive tool to identify carotid plaque vulnerability and risk stratification.

[IgG4-related diseases of retroperitoneum in urinary and male reproductive system: a clinicopathological analysis of eleven cases]

Objective: To analyze the clinicopathological features of IgG4-related diseases (RD) of retroperitoneum and the urinary and male reproductive system (IgG4-RUMR). Methods: A total of 11 IgG4-RUMR cases from January 2013 to March 2021 were retrospectively collected at Peking University Third Hospital and Shandong Provincial Hospital affiliated to Shandong First Medical University. The clinicopathologic features, laboratory and imaging findings were analyzed and scored according to the 2019 ACR/EULAR classification criteria for IgG4-RD. Results: The 11 patients (male:female is 9∶2; mean age 59 years, range from 44 to 83 years) were initially admitted to the Deparment of Urology/Kidney Transplantation (10 cases) and the Department of Oncology (1 case). All patients had urogenital disorders or imaging abnormalities. Three of the 11 patients had a history of IgG4-RD such as lacrimal gland engorgement, salivary gland engorgement and IgG4-associated pancreatitis. Abnormal retroperitoneal soft tissue and hydronephrosis were found in eight cases, while epididymal and spermatic cord masses were found in one case, simple renal mass in one case, and"benign prostatic hyperplasia"in one case. In the 10 patients tested for serum IgG4, the serum IgG4 level was 0.8-14.4 g/L. Histologically, all cases showed significant lymphoplasmacytic infiltration and storiform fibrosis, and some were accompanied by obliterative phlebitis. The number of IgG4 positive plasma cells was 12-155 per high-power field, and the IgG4/IgG ratio was 15%-77%. According to the 2019 ACR/EULAR IgG4-RD classification standard 11 cases scored 20-48 points, all of which met the diagnostic criteria of IgG4-RUMR. Therapeutically, the patient with a simple renal mass underwent partial nephrectomy. The patient with prostate lesion underwent transurethral resection of prostate and was initially diagnosed as nonspecific chronic prostatitis. Later, the patient was admitted again because of salivary gland swelling, and the pathologic diagnosis was amended. The patient with epididymal and spermatic cord masses participated in a clinical trial about retroperitoneal fibrosis. The remaining eight patients received symptomatic treatment such as adhesiolysis and stent placement. All the patients were subsequently treated with glucocorticoid/immunosuppressant and symptoms relieved. Conclusions: IgG4-RUMR is uncommon. In clinical practice, information from clinical, serologic, radiologic and pathologic evaluations must be integrated. IgG4-RUMR should be considered in the differential diagnosis of urinary and male reproductive diseases. The 2019 ACR/EULAR classification criteria for IgG4-RD, while relatively complex, are objective and practical in the diagnosis of IgG4-RUMR.

Monitoring silver diamine fluoride application with optical coherence tomography

The objective of this study was to investigate the use of optical coherence tomography (OCT) for monitoring changes in the structure of caries lesions overtime after treatment with silver diamine fluoride (SDF). Artificial caries lesions were formed on dentin bovine blocks. Each block was partitioned into 5 windows: one lesion was covered by nail varnish as control (LC), one sound window was covered with nail varnish (SC), one sound window was exposed to SDF (SCT), one lesion received 2 applications of SDF (L2), while the other lesion received one application of SDF (L1). Each window was scanned using OCT before SDF application, and every week subsequently, for 12 weeks after initial SDF treatment. Parameters such as mean intensity and the width of the peak of increased reflectivity located at the sample surface and the intensity at a depth of 180-μm were monitored. High-resolution microscopy was also used to for the analysis of selected samples. Changes in the parameters measured showed significant changes on dentin lesions after SDF application. OCT resolved structural changes after SDF application as well as changes overtime. High resolution microscopy images confirm penetration of SDF into the samples. Such changes can potentially be monitored to determine if and when re-application of SDF is needed.

Micro-coil probes for magnetic intracortical neural stimulation: Trade-offs in materials and design

Neural probes for intracortical neuromodulation in the brain have advanced with the developments in micro- and nanofabrication technologies. Most of these technologies for the intracortical stimulation have relied on the direct electrical stimulation via electrodes or arrays of electrodes. Generating electric fields using time-varying magnetic fields is a more recent neuromodulation technique that has proven to be more specifically effective for the intracortical stimulation. Additionally, current-actuated coils require no conductive contact with tissues and enable precise tailoring of magnetic fields, which are unaffected by the non-magnetic nature of the biological tissue and encapsulation layers. The material and design parameter space for such micro-coil fabrication can be optimized and tailored to deliver the ideal performance depending on the parameters needed for operation. In this work, we review the key requirements for implantable microcoils including the probe structure and material properties and discuss their characteristics and related challenges for the applications in intracortical neuromodulation.

Barriers and strategies for oral medication adherence among children and adolescents with Type 2 diabetes

AIMS

Examine barriers for taking glucose-lowering oral medications, associated baseline characteristics, strategies used, and the adherence impact in the Treatment Options for Type 2 Diabetes in Adolescents and Youth (TODAY) study.

METHODS

We studied youth prescribed oral diabetes medications over two years (N = 611, 583, and 525 at 6, 12, and 24 months). Clinicians documented barriers (e.g. forgetting, routines, other concerns) in the subsample that reported missed doses (N = 423 [69.2%], 422 [72.4%], and 414 [78.9%] at 6, 12, and 24 months, respectively). Adherence strategies were also assessed (e.g. family, schedule, reminder device) using standard questions. Logistic regression was used to analyze associations with medication adherence.

RESULTS

Those missing doses were not different from the total sample (61.5% female, 13.9 ± 2.0 years, >80% racial/ethnic minorities). No baseline demographic or clinical predictors of barriers to medication adherence were identified. Among those for whom barriers were assessed, "forgetting" with no reason named (39.3%) and disruptions to mealtime, sleep, and schedule (21.9%) accounted for the largest proportion of responses. Family support was the primary adherence strategy identified by most youth (≥50%), followed by pairing the medication regimen with daily routines (>40%); the latter strategy was associated with significantly higher adherence rates (p = 0.009).

CONCLUSIONS

Family supported medication adherence was common in this mid-adolescent cohort, but self-management strategies were also in evidence. Findings are similar to those reported among youth with other serious chronic diseases. Prospective studies of multi-component family support and self-management interventions for improving medication adherence are warranted.

TRIAL REGISTRATION

ClinicalTrials.gov NCT00081328.

Abstract P6-12-11: A randomized, double-blind, placebo-controlled window of opportunity trial evaluating clinical effects of high dose vitamin D in patients with breast cancer

This abstract was withdrawn by the authors.

Association between lutein intake and lutein concentrations in human milk samples from lactating mothers in South Korea

This study was performed to investigate the association between maternal lutein intake and lutein concentrations in human milk among exclusive breast-feeding and mixed-feeding groups of lactating mothers in South Korea. From 99 women who were recruited from March to July 2015, dietary data and breast milk samples were obtained. The means of the daily lutein intakes and breast milk lutein concentrations in lactating mothers were 4.04 mg/day and 10.06 μg/dl, respectively, and they did not differ according to the type of breast-feeding. Breast milk lutein concentrations were positively correlated with the dietary lutein intake of lactating mothers after adjustment for the infant's age and supplement use by the lactating women (r=0.3337, P=0.0008). These correlations appeared in both groups. Further research is needed to identify whether breast milk lutein levels influence infant health, especially eye health.European Journal of Clinical Nutrition advance online publication, 25 May 2016; doi:10.1038/ejcn.2016.84.

Relationship between body-mass index and serum folate concentrations in pregnant women

The concentration of micronutrients impacts fetal development and pregnancy outcome and has been suggested to be negatively correlated with the body-mass index (BMI). We evaluated the relationship between BMI and the serum folate concentration in 802 and 660 Korean pregnant women in mid- and late pregnancy, respectively, who participated in a multicenter prospective study. There was a significant negative correlation between BMI value and the serum folate concentration at mid- and late pregnancy (P for trend 0.001 and 0.024, respectively). A general linear model confirmed this correlation at both time points after adjusting for gestational age and total folate intake. These findings are important as the serum folate concentration is a rate-limiting factor for placental folate transport to the fetus, and an inadequate folate supply may cause various malformations.

Dipole localization using beamforming and RAP-MUSIC on simulated intracerebral recordings

Interpreting intracerebral recordings in the search of an epileptic focus can be difficult because the amplitude of the potentials are misleading. Small generators located near the electrode site generate large potentials, which could swamp the signal of a nearby epileptic focus. In order to address this problem, two inverse problem algorithms, beamforming and recursively applied and projected multiple signal classification (RAP-MUSIC), were used with simulated intracerebral potentials to calculate equivalent dipole positions. Three dipoles were positioned in an infinite plane medium near three intracerebral electrodes. The potentials generated by the dipoles were simulated and contaminated with white noise. Initial localization simulations showed that both methods detected the sources accurately with RAP-MUSIC reporting lower orientation errors. A spatial resolution analysis for both methods was undertaken in which two dipoles were placed on a plane with the same orientation and overlapping time-courses. Beamforming was able to adequately distinguish the sources for separation distances of 1.2 cm, whereas RAP-MUSIC managed to separate the sources for dipoles as close as 0.4-0.6 cm.

Effects of the interaction between the C677T 5,10-methylenetetrahydrofolate reductase polymorphism and serum B vitamins on homocysteine levels in pregnant women

OBJECTIVE

The purpose of this study was to investigate the effect of the interaction between the C677T mutation in the 5,10-methylenetetrahydrofolate reductase (MTHFR) genotypes and serum levels of B vitamins on serum homocysteine levels in pregnant women.

DESIGN

A cross-sectional study.

SETTING

Ewha Womans University Hospital, Seoul, Korea.

SUBJECTS

A total of 177 normal pregnant women, 24.6+/-1.1 weeks of gestation, in a 6-month period during 2001-2002.

INTERVENTIONS

Serum vitamin B2, vitamin B6, and homocysteine analyses were conducted using high-performance liquid chromatography methods. Serum folate and vitamin B12 concentrations were determined using a radioimmunoassay kit. MTHFR gene mutation was investigated by the polymerase chain reaction of a genomic DNA fragment.

RESULTS

Serum homocysteine was higher in women with the T/T genotype than those with the C/T or C/C genotype of the MTHFR gene (P<0.05). Serum homocysteine was negatively correlated with serum folate in all MTHFR genotypes (P<0.001), and the correlation between the two serum levels was the strongest in the T/T genotype. Serum homocysteine was higher in the subjects with the T/T MTHFR genotype only when the serum folate was below the median level. Explanatory power of B vitamin status as predictors of serum homocysteine levels was more pronounced in the T/T genotypes (68.5%) compared with the C/T (37.9%) or C/C genotypes (20.6%).

CONCLUSIONS

Serum homocysteine levels in pregnant women varied significantly with MTHFR genotype and the serum B vitamin status. Higher serum folate, vitamin B2, and vitamin B12 concentrations may lessen the MTHFR genotypic effect on serum homocysteine levels.

Development of a Canadian standardized protocol for subtyping methicillin-resistant Staphylococcus aureus using pulsed-field gel electrophoresis

A panel of 24 methicillin-resistant Staphylococcus aureus strains was distributed to 15 laboratories in Canada to evaluate their in-house pulsed-field gel electrophoresis (PFGE) protocols and interpretation criteria. Attempts to compare fingerprint images using computer-aided analysis were not successful due to variability in individual laboratory PFGE protocols. In addition, individual site interpretation of the fingerprint patterns was inadequate, as 7 of 13 sites (54%) made at least one error in interpreting the fingerprints from the panel. A 2-day standardized PFGE protocol (culture to gel image) was developed and distributed to all of the sites. Each site was requested to use the standardized protocol on five strains from the original panel. Thirteen sites submitted gel images for comparisons. The protocol demonstrated excellent reproducibility and allowed interlaboratory comparisons with Molecular Analyst DST software (Bio-Rad) and 1.5% band tolerance.

Insulin and IGF-I inhibit calcium-dependent chloride secretion by T84 human colonic epithelial cells

D-Myo-inositol (3,4,5,6) tetrakisphosphate [Ins(3,4,5,6)P(4)] or phosphatidylinositol 3-kinase (PI 3-kinase) activity acts to inhibit calcium-dependent chloride secretion in T84 colonic epithelial cells. To further distinguish between the contributions of these two signaling pathways to the inhibition of secretion, we studied effects of insulin, because the insulin receptor links to PI 3-kinase but not to pathways postulated to generate Ins(3,4,5,6)P(4). Chloride secretion across T84 cell monolayers was studied in Ussing chambers. Activation of PI 3-kinase was assessed by Western blotting. Basolateral, but not apical, addition of insulin inhibited carbachol- and thapsigargin-induced chloride secretion in a time- and concentration-dependent fashion. Insulin-like growth factor-I (IGF-I) had similar effects. Insulin had no effect on Ins(3,4,5,6)P(4) levels, and the inhibitory effects of insulin and IGF-I on chloride secretion were fully reversed by the PI 3-kinase inhibitors wortmannin and LY-294002. Western blot analysis showed that both insulin and IGF-I recruited the 85-kDa regulatory and 110-kDa catalytic subunits of PI 3-kinase to anti-phosphotyrosine immunoprecipitates. In conclusion, insulin and IGF-I act to inhibit calcium-dependent chloride secretion through a PI 3-kinase-dependent pathway. Because insulin is released in a pulsatile fashion postprandially and IGF-I levels are elevated in pathological settings, our findings may have physiological and/or pathophysiological significance.

mu-conotoxin GIIIA interactions with the voltage-gated Na(+) channel predict a clockwise arrangement of the domains

Voltage-gated Na(+) channels underlie the electrical activity of most excitable cells, and these channels are the targets of many antiarrhythmic, anticonvulsant, and local anesthetic drugs. The channel pore is formed by a single polypeptide chain, containing four different, but homologous domains that are thought to arrange themselves circumferentially to form the ion permeation pathway. Although several structural models have been proposed, there has been no agreement concerning whether the four domains are arranged in a clockwise or a counterclockwise pattern around the pore, which is a fundamental question about the tertiary structure of the channel. We have probed the local architecture of the rat adult skeletal muscle Na(+) channel (mu1) outer vestibule and selectivity filter using mu-conotoxin GIIIA (mu-CTX), a neurotoxin of known structure that binds in this region. Interactions between the pore-forming loops from three different domains and four toxin residues were distinguished by mutant cycle analysis. Three of these residues, Gln-14, Hydroxyproline-17 (Hyp-17), and Lys-16 are arranged approximately at right angles to each other in a plane above the critical Arg-13 that binds directly in the ion permeation pathway. Interaction points were identified between Hyp-17 and channel residue Met-1240 of domain III and between Lys-16 and Glu-403 of domain I and Asp-1532 of domain IV. These interactions were estimated to contribute -1.0+/-0.1, -0.9+/-0.3, and -1.4+/-0.1 kcal/mol of coupling energy to the native toxin-channel complex, respectively. mu-CTX residues Gln-14 and Arg-1, both on the same side of the toxin molecule, interacted with Thr-759 of domain II. Three analytical approaches to the pattern of interactions predict that the channel domains most probably are arranged in a clockwise configuration around the pore as viewed from the extracellular surface.

Corneal insult affects the production and distribution of FGF-2 within the lacrimal gland

The purpose of this study was to determine the distribution of FGF-2 within rabbit lacrimal glands and to determine whether corneal insult affects that distribution. The scarified corneas of experimental animals were inoculated either with adenovirus type 5 or buffer. Control animals were either untreated, or animals whose corneas were scarified. Twenty-one days later all animals were killed and the lacrimal glands were studied by immunocytochemistry and Western blotting to detect FGF-2. In untreated control animals, FGF-2 was immunolocalized predominantly within a population of elongated cells in the basal epithelium of ducts, and to a lesser degree in the basal epithelium of the acini. The elongated immunopositive cells appear to be myoepithelial cells known to be present at these sites. Interstitial cells around ducts and acini, and the basement membranes of the ducts and acini, were also immunopositive for FGF-2. Twenty-one days after adenovirus inoculation and scarification of the cornea, immunopositivity for FGF-2 was dramatically decreased in basement membranes, but increased within myoepithelial cells of the duct epithelium. These myoepithelial cells were frequently enlarged, bulging toward the duct lumen. In animals whose corneas were inoculated with buffer and scarified, or animals whose corneas were simply scarified, the changes in the lacrimal gland were similar, but somewhat less pronounced, to those of adenovirus-inoculated animals. Western blots confirmed the presence of FGF-2 immunoreactivity in all groups. The major band in untreated controls was at 24 kD, whereas all animals with corneal scarification had major bands at 38 kD. Densitometry of Western blots demonstrated that the amount of 24 kD FGF-2 present within the lacrimal gland after corneal scarification was at least 50% less than in untreated controls, whereas 38 kD FGF-2 was at least ten-fold greater. Our findings indicate that corneal scarification results in an altered distribution of FGF-2 within the lacrimal gland, which involves a decrease in low molecular weight FGF-2 and a dramatic increase in a higher molecular weight isoform of FGF-2. FGF-2 may be released from myoepithelial cells apically (exocrine) into the tear fluid and basally (autocrine/paracrine) into the connective tissue, as well as from extracellular complexes within basal laminae.

A comparison of 12- and 15-lead ECGS in ED chest pain patients: impact on diagnosis, therapy, and disposition

The objective of this study was to investigate the diagnostic and therapeutic impact of the 15-lead electrocardiogram (15ECG) on the emergency department (ED) management of chest pain (CP) patients. The design was prospective use of 15ECG with real-time physician survey and retrospective comparison to 12-lead ECG (12ECG). The study took place in a University hospital ED. Adult CP patients participated. During the 15ECG period (June 1996 to July 1996), 595 patients (92% of CP patients) had 15ECG analysis. Diagnoses of acute coronary ischemic syndromes (ACIS) were as follows: 13 acute myocardial infarction (AMI, 7 anterior [ANT], 5 inferior [INF], 1 lateral [LAT], 2 posterior [POST], 1 right ventricular [RV]) and 136 unstable angina (USA) with 47% exhibiting ECG abnormality; the 2 POST and 1 RV AMI occurred in the setting of coexisting INF AMI. The following management strategies were used: 6 fibrinolytic therapy (TT), 4 primary angioplasty (PTCA), 67 rule-out myocardial infarction (ROMI), and 144 admission to critical care unit (CCU). During the 12ECG period (June 1995 to July 1995), 599 patients were encountered. The diagnoses of ACIS were as follows: 11 AMI (5 ANT, 4 INF, 2 LAT) and 146 USA with 51% exhibiting ECG abnormality (P = NS for diagnostic comparisons to 15ECG). The following management strategies were used: 5 TT, 5 PTCA, 59 ROMI, and 137 admission to CCU (P = NS for all treatment comparisons to 15ECG). Of 15ECG cases 81% had completed real-time physician survey, showing that the diagnosis and management ACIS were not altered by the 15ECG; physicians felt, however, that the 15ECG provided a more complete anatomic picture of the ACIS. No false-positive cases of additional lead STE were noted in this investigation except in cases involving abnormal intraventricular conduction such as the bundle branch block scenario. The 15ECG provided a more complete description of myocardial injury without altering the ED diagnosis, ED-based therapy, or hospital disposition in adult CP patients. Further study is required to identify patient subset(s) which may benefit from the 15ECG.

Dietary protein content affects the profiles of extracellular amino acids in the medial preoptic area of freely moving rats

This study examined the effect of protein consumption on extracellular amino acid concentrations in the medial preoptic area (MPOA) of rats. Rats were given free access to diets containing 0, 25 or 50 % protein for 3-h duration, starting from the onset of dark cycle (1800 h). The microdialysis probe was implanted into the MPOA at 1500 h. Dialysates were collected every 20 min from 1700 h to 2100 h. Amino acid concentrations in dialysate samples were determined by reverse phase-HPLC. Extracellular amino acid concentrations in the MPOA were elevated by protein consumption within 20 to 40 min following the start of the meal. The 50 % protein diet resulted in increased (p<0.05) alanine, glutamine, isoleucine, leucine, methionine, tyrosine and valine concentrations, when compared with both baseline and the 0% protein diet. When the 25 % protein diet was fed, amino acid concentrations in the MPOA were between those after the 0 and 50% protein diets. The ratio of tryptophan to the total branched-chain amino acids in extracellular fluid was highest after the 0% protein diet and increased with time. We conclude that extracellular amino acid profiles in the MPOA are affected by dietary protein content.

An intragastric amino acid mixture influences extracellular amino acid profiles in the lateral hypothalamic area of freely moving rats

We tested the effect of equicaloric loads of glucose (0.89 g) or a balanced amino acid mixture (0.85 g) on extracellular amino acid concentrations in the brains of freely moving rats. At 15:30 hours, the microdialysis probe was inserted into the lateral hypothalamic area of ambulatory rats, and food and water were removed. Dialysates were collected every 20 min from 1 h prior to gavage (18:00 hours) and until 3 h after the gavage. Amino acid concentrations in the dialysate were determined by reverse-phase HPLC. Following the amino acid gavage, extracellular amino acid concentrations significantly increased from baseline for alanine, isoleucine, leucine, methionine, threonine, tyrosine, and valine. Those elevations occurred within 20-40 min following the amino acid load, and lasted up to 100 min. After the glucose and water treatments, amino acid concentrations were either not affected or gradually diminished from baseline. We conclude that extracellular amino acid concentration in the lateral hypothalamus is influenced by the composition of food consumed.

Cross-Canada spread of methicillin-resistant Staphylococcus aureus via transplant organs

We report our investigation of the transmission of methicillin-resistant Staphylococcus aureus (MRSA) through transplantation. The kidneys, liver, and corneas were harvested from a child who died in Nova Scotia. Several days postmortem it was learned that culture of a premortem endotracheal tube aspirate from the donor yielded MRSA. Both kidneys were transplanted into a child in Nova Scotia and the liver into a child in Alberta. Both recipients subsequently became blood culture-positive for MRSA. One corneal ring from the donor was MRSA-positive. All four MRSA isolates were mecA-positive by polymerase chain reaction (PCR). The relatedness of the MRSA isolates was examined by restriction fragment length polymorphism (RFLP) analysis, a 16S-23S ribosomal PCR typing method, and comparison of antibiograms. Results were identical for all four MRSA isolates. These findings indicate that MRSA from the donor was transferred to recipients during implantation of harvested organs in Alberta and Nova Scotia, a cross-Canada spread.

A standardized protocol for the rapid preparation of bacterial DNA for pulsed-field gel electrophoresis

A rapid method for the preparation of bacterial DNA for pulsed-field gel electrophoresis was developed for Gram-positive and Gram-negative bacteria. This method was accomplished by reducing the time for the cell lysis reaction, restriction endonuclease digestion, and electrophoresis to 1, 1.5, and 18 h, respectively. The whole procedure from the initial bacterial culture plate to the final analysis of restriction fragments can be completed within 24 h. This rapid method was successfully achieved for Staphylococcus aureus, Enterococcus faecalis, Neisseria gonorrhoeae, Salmonella typhimurium, Serratia marcescens, and Stenotrophomonas maltophilia.

Use of hypothermic circulatory arrest for cerebral protection during aortic surgery

Optimal use of hypothermic circulatory arrest during aortic surgery requires understanding of its physiology. Research in laboratory animals and clinical observations have now documented that considerable residual cerebral metabolism remains with cooling to levels of 15-18 degrees C, especially if cooling intervals are short, reflected by persistent jugular venous desaturation. Cooling should be continued to below 15 degrees C if the duration of HCA is expected to exceed 20 minutes, and continued until jugular venous saturations exceed 95%. There is considerable laboratory evidence that even short durations of HCA are followed by a prolonged interval of increased cerebral vascular resistance during which cerebral metabolism is maintained at normal levels by markedly increased oxygen extraction. Clinical observations have now confirmed that considerable jugular venous desaturation is present in patients following HCA: it is more pronounced with prolonged HCA, and is still present as late as six hours after the start of rewarming. This reinforces the concept of a prolonged postoperative vulnerable interval following HCA, during which any compromise in oxygen delivery has the potential for producing cerebral injury. Several adjunctive measures have been shown to improve outcome following HCA. The simplest and most important is topical hypothermia: packing the head in ice during the interval of HCA. Retrograde cerebral perfusion (RCP) has also been shown to improve EEG recovery as well as histological and behavioral outcome in laboratory animals following prolonged HCA, but some of its effect may be secondary to its efficacy in keeping the brain cold, since RCP provides very low rates of flow and supports metabolism at a much lower level than antegrade perfusion at the same temperature. But despite the clear superiority of antegrade perfusion, and the documentation of some benefits of RCP in laboratory measures of cerebral protection, clinical results using RCP and ACP have not yet demonstrated the superiority of these methods over use of HCA alone, perhaps because these modalities are usually employed in patients with unusually high risk of neurological injury: those with dissection or with clot or atheroma in the aorta. Nevertheless, recent years have seen considerable reduction in mortality following aortic surgery, especially in older patients, and a trend toward a lower incidence of permanent neurologic dysfunction. The presence of preoperative rupture or hemodynamic compromise, and of clot or atheroma in the aorta, remain the most significant risk factors both for death and occurrence of stroke.

Construction of a Genomic Map of H. pylori by Pulsed-Field Gel Electrophoresis (PFGE)

The inability of conventional gel electrophoresis to separate DNA molecules exceeding 50 kb in size led to the development of pulsed-field gel electrophoresis (PFGE) by Schwartz et al, (1)in 1982. He introduced the concept of applying two alternating electric fields (i.e., pulsed-field) to separate DNA molecules greater than 50 kb embedded in an agarose gel matrix. Since then, many instruments based on this principle have been developed. For a discussion of various pulsed-field applications, see review articles by Lai et al. (2) and Crété et al. (3). It was shown that, under the influence of an electric field, a DNA molecule embedded in a gel matrix undergoes reorientation, elongation, and migration along the field toward the anode. When a second field is applied in an alternate direction, the DNA molecule must reorientate, elongate, and migrate along the direction of the new field. Larger DNA molecules will take longer to reorientate than smaller molecules; therefore the larger ones spend less time migrating down the gel than the smaller per pulse time. Consequently, larger DNA molecules will appear near the origin while the smaller molecules will migrate furthest. This principle becomes important when different fragment sizes of DNA are to be separated. PFGE has become an important tool for determining genome sizes, physical mapping of the chromosome, and localization of genes on the chromosome of prokaryotic micro-organisms.

Expanded genomic map of Campylobacter jejuni UA580 and localization of 23S ribosomal rRNA genes by I-CeuI restriction endonuclease digestion

The genomic map of Campylobacter jejuni UA580 was expanded and more precisely constructed using I-CeuI, Sal/I and SmaI restriction endonucleases in conjunction with pulsed-field gel electrophoresis (PFGE). The presence of three fragments after digestion with I-CeuI confirmed the presence of three copies of the 23S ribosomal rRNA (rrl) gene. The genome size of Campylobacter jejuni UA580 was determined to be 1725 +/- 5.9 kbp by I-CeuI with fragment sizes of 1053 +/- 4.4, 361 +/- 2.7 and 311 +/- 3.6 kbp. Analysis of a PCR product from C. jejuni UA580 23S rRNA gene showed that I-CeuI did cut within the gene. The precise locations of the three genes were determined using I-CeuI with two copies of the 23S and 5S rRNA genes located separately from the 16S rRNA gene whereas the third copy of the 23S and 5S rRNA genes had a closer linkage to a 16S rRNA gene copy. Homologous gene probes were used to map additional genes and allowed the realignment of a few previously mapped genes on the chromosome. Other strains of C. jejuni were also cut into three fragments with I-CeuI, which generated variable PFGE patterns.

Genome map of Campylobacter fetus subsp. fetus ATCC 27374

A physical map of the chromosome of Campylobacter fetus subsp. fetus was constructed by using pulsed-field gel electrophoresis of restriction fragments generated by SalI, SmaI and NotI. Digestion of the type strain ATCC 27374 with these restriction endonucleases resulted in generating 4-14 fragments. The order of the fragments was deduced from hybridization of these restriction fragments to Southern blots of pulsed-field gel electrophoresis gels generated by the other two enzymes. The estimated genome size was 1160 kb. The position of several homologous and heterologous genes was determined on the circular map. These included the 2.8-kb sapA gene, encoding the 97-kDa surface array protein. Three copies of ribosomal RNA genes for which the 16S, 23S and 5S rRNA appeared to be located in close proximity in each of the three regions. The RNA polymerase genes rpoA, rpoB, and rpoD were mapped and appeared to be situated close together in one region. The flagellin genes (flaAB) of C. jejuni and the gyrase genes gyrA and gyrB of C. perfringens and Bacillus subtilis, respectively, were used to identify the locations of flaAB, the gyrA and the gyrB genes on the ATCC 27374 chromosome.

Microdialysis as a tool to measure dietary and regional effects on the complete profile of extracellular amino acids in the hypothalamus of rats

Regional and dietary-induced changes in hypothalamic extracellular amino acid concentrations were examined. Microdialysis probes were simultaneously implanted in the hypothalamic paraventricular nucleus (PVN) and the lateral hypothalamus (LH) of anesthetized rats and perfused at a rate of 2 microliters/min. Dialysates were collected every 20 min for 1 h prior to gavage of a balanced amino acid mixture (0.85 g patterned after 1 g of chicken egg albumin) and then every 20 min for 3 h after treatment. Tail vein blood samples were also collected. Marked changes in plasma levels of most amino acids were evident immediately following the amino acid gavage. In the PVN, concentrations of isoleucine, leucine, methionine and valine all increased within 40 min, whereas significant decreases in glutamine, histidine and taurine were observed in the LH. In a separate study, PVN extracellular amino acid concentrations were examined in awake, freely-behaving rats following gavage of equicaloric loads of a balanced amino acid mixture, glucose (0.89 g) or water. Dialysate levels of glutamate, isoleucine, leucine, methionine, threonine, tyrosine and valine showed reliable increases after amino acid treatment, although the overall time course of these effects differed somewhat. The amino acid profile of the PVN was, in general, unaffected by glucose administration. These findings suggest that specific brain regions may respond uniquely to amino acid ingestion and further imply that dietary composition may influence the amino acid profiles of the extracellular fluid in brain.

Characterization of chromosomal DNA profiles from Helicobacter pylori strains isolated from sequential gastric biopsy specimens

The restriction endonuclease profiles of DNAs from Helicobacter pylori strains isolated from 20 patients in two or more consecutive biopsy specimens over a period of up to 2 years were analyzed by pulsed-field gel electrophoresis with NotI and NruI. H. pylori strains possess a high degree of genomic diversity which was not observed to occur in vivo, and attempts to observe it in vitro were not successful.

Genome conservation in Helicobacter mustelae as determined by pulsed-field gel electrophoresis

Genomic DNA from 15 strains of Helicobacter mustelae was subjected to pulsed-field gel electrophoresis (PFGE) after digestion with PacI and SfiI. H. mustelae genome DNA appeared very similar in all strains examined, whether isolated from ferrets or mink or from animals bred in either the USA or in the UK. The H. mustelae genome size was estimated to be 1.7 Mb, similar in size to that of H. pylori. A minor difference in PacI PFGE pattern and genome size was observed between rifampicin-resistant and rifampicin-susceptible derivatives of H. mustelae F251. Another minor difference in genome pattern based on PFGE with SfiI was observed between an H. mustelae strain used to experimentally infect four ferrets which resulted in loss of an SfiI site in strains obtained from the newly infected ferrets. Thus, although minor differences in PFGE pattern were noted, H. mustelae lacks the genomic diversity observed in H. pylori.

Construction of a Helicobacter pylori genome map and demonstration of diversity at the genome level

Genomic DNA from 30 strains of Helicobacter pylori was subjected to pulsed-field gel electrophoresis (PFGE) after digestion with NotI and NruI. The genome sizes of the strains ranged from 1.6 to 1.73 Mb, with an average size of 1.67 Mb. By using NotI and NruI, a circular map of H. pylori UA802 (1.7 Mb) which contained three copies of 16S and 23S rRNA genes was constructed. An unusual feature of the H. pylori genome was the separate location of at least two copies of 16S and 23S rRNA genes. Almost all strains had different PFGE patterns after NotI and NruI digestion, suggesting that the H. pylori genome possesses a considerable degree of genetic variability. However, three strains from different sites (the fundus, antrum, and body of the stomach) within the same patient gave identical PFGE patterns. The genomic pattern of individual isolates remained constant during multiple subcultures in vitro. The reason for the genetic diversity observed among H. pylori strains remains to be explained.

Genome maps of Campylobacter jejuni and Campylobacter coli

Little information concerning the genome of either Campylobacter jejuni or Campylobacter coli is available. Therefore, we constructed genomic maps of C. jejuni UA580 and C. coli UA417 by using pulsed-field gel electrophoresis. The genome sizes of C. jejuni and C. coli strains are approximately 1.7 Mb, as determined by SalI and SmaI digestion (N. Chang and D. E. Taylor, J. Bacteriol. 172:5211-5217, 1990). The genomes of both species are represented by single circular DNA molecules, and maps were constructed by partial restriction digestion and hybridization of DNA fragments extracted from low-melting-point agarose gels. Homologous DNA probes, encoding the flaAB and 16S rRNA genes, as well as heterologous DNA probes from Escherichia coli, Bacillus subtilis, and Haemophilus influenzae, were used to identify the locations of particular genes. C. jejuni and C. coli contain three copies of the 16S and 23S rRNA genes. However, they are not located together within an operon but show a distinct split in at least two of their three copies. The positions of various housekeeping genes in both C. jejuni UA580 and C. coli UA417 have been determined, and there appears to be some conservation of gene arrangement between the two species.

In vitro susceptibilities of Campylobacter jejuni and Campylobacter coli to azithromycin and erythromycin

MICs of azithromycin and erythromycin for 20 Campylobacter coli and 20 Campylobacter jejuni strains were determined. The results demonstrated that, for Campylobacter species, all high-level erythromycin-resistant strains were also resistant to azithromycin and that azithromycin did not exhibit increased potency in comparison with that of erythromycin.

Protein separation and purification in neat dimethyl sulfoxide

Pure DMSO (instead of water) is used as the reaction medium for protein separations. It is shown that common extracellular proteins (i) have high solubility in DMSO (1-50 mg/ml), (ii) do not irreversibly inactivate in this solvent, and (iii) can adsorb onto carboxymethyl cellulose in DMSO and be subsequently fully desorbed in this solvent by inorganic salts. Ion-exchange chromatography on this resin in DMSO has been used to purify bovine pancreatic trypsin and to separate it from hen egg-white lysozyme in their mixture. Another approach to protein separation in DMSO, fractional precipitation with ethyl acetate (which does not dissolve proteins), has been verified with a mixture of bovine pancreatic chymotrypsinogen and chicken egg ovalbumin.

Pulsed-field gel electrophoresis of Campylobacter jejuni and Campylobacter coli genomic DNA and its epidemiologic application

Genomic DNA from 12 different Campylobacter jejuni and 10 Campylobacter coli isolates was digested with SmaI and analyzed by pulsed-field gel electrophoresis (PFGE) and 16S rRNA hybridization studies. Although the two Campylobacter species displayed species-specific restriction and hybridization patterns, significant intraspecies differences were observed. Combined PFGE and hybridization pattern analysis failed to provide any more epidemiologic information than was obtained from PFGE restriction profiles alone. Therefore, results from these studies indicate that PFGE analysis of SmaI-restricted genomic DNA provides a reliable means of differentiating C. jejuni from C. coli and may represent a more practical approach to epidemiologic studies than combining conventional DNA restriction digestion pattern with RNA hybridization procedures.