Naringin and naringenin inhibit nitrite-induced methemoglobin formation

Naringin and naringenin protect hemoglobin from nitrite-induced oxidation to methemoglobin. The protection is not observed when naringin and naringenin are added after the autocatalytic stage of the oxidation of hemoglobin by nitrite. The ability of naringin and naringenin to scavenge oxygen free radicals may be responsible for the action because superoxide, hydroxyl and other free radicals are implicated in promoting the autocatalytic stage of oxidation of hemoglobin by nitrite. Both compounds showed less ability to protect intact erythrocytes suggesting that they may not cross the erythrocyte membrane in sufficient amounts. Naringenin was more effective than naringin, probably because of the extra phenolic group in the aglycone.

Differences in early virus loads with different phenotypic variants of HIV-1 and SIV(cpz) in chimpanzees

OBJECTIVE

A comparative study of the replication kinetics of different HIV-1 variants (including SIV(cpz)) was undertaken to determine which viral characteristics were associated with sustained plasma viraemia in chimpanzees.

DESIGN

Plasma samples from chimpanzees infected with six different HIV-1 clade B isolates were compared with plasma samples from SIV(cpz-ant)-infected chimpanzees.

METHODS

A pan-clade quantitative competitive reverse transcriptase-polymerase chain reaction assay was developed based on conserved primer sequences recognizing M, N and O human lentiviruses as well as different SIV(cpz) isolates.

RESULTS

Important differences between early kinetics in the human lentivirus isolates as well as compared with the chimpanzee isolate SIV(cpz-ant) were observed. R5-dependent non-syncytium-inducing (NSI) isolates (5016, Ba-L, SIV(cpz)) were found to have relatively higher viral loads than the syncytium-inducing (SI), X4-dependent primary (SF2), T cell-adapted (IIIB) or X4/R5 (Han2, DH12) SI primary isolates.

CONCLUSION

Infection of chimpanzees with NSI R5-utilizing isolates correlated with persistent viraemia (approximately 10(4) RNA equivalents/ml) in contrast to transient viraemia observed after infection with SI X4-utilizing isolates.

Diversity of Salmonella serotypes in cull (market) dairy cows at slaughter

OBJECTIVE

To determine the diversity of Salmonella serotypes isolated from a large population of cull (market) dairy cows at slaughter.

DESIGN

Cross-sectional study.

SAMPLE POPULATION

Salmonella organisms isolated from the cecal-colon contents of 5,087 market dairy cows.

PROCEDURE

During winter and summer 1996, cecal-colon contents of cull dairy cows at slaughter were obtained from 5 US slaughter establishments. Specimens were subjected to microbiologic culturing for Salmonella spp at 1 laboratory. Identified isolates were compared with Salmonella isolation lists published by the Centers for Disease Control and Prevention (CDC) and the National Veterinary Services Laboratory (NVSL) for approximately the same period. The Simpson diversity index was used to calculate the likelihood that Salmonella isolates selected randomly by establishment were different.

RESULTS

Of 58 Salmonella serotypes identified, Salmonella ser. Montevideo was the most prevalent. Two of the top 10 CDC serotypes identified from in 1996, Salmonella ser. Typhimurium and S Montevideo, appeared on our top 10 list; 8 of the top 10 were found on NVSL listings. Thirty-one of 59 S. Typhimurium isolates were identified as DT104 and found at a west slaughter establishment, 30 during the winter and 1 during the summer. The greatest diversity of serotypes was at a southeast establishment during the summer; the least diversity was at a central establishment in the winter.

CONCLUSIONS AND CLINICAL RELEVANCE

58 Salmonella serotypes were isolated from market dairy cows at slaughter and could pose a threat for food-borne illness. Salmonella Montevideo was the most frequently isolated serotype and may contribute substantially to salmonellosis in dairy cattle.

Prevalence of Salmonella spp in cull (market) dairy cows at slaughter

OBJECTIVE

To determine the prevalence of Salmonella spp in the cecal-colon contents of cull (market) dairy cows at slaughter because of potential public health ramifications.

DESIGN

Survey study.

SAMPLE POPULATION

Cecal-colon contents collected from 5,087 cull (market) dairy cows at slaughter at 5 slaughter establishments across the United States.

PROCEDURE

During 2 periods of the year, winter (January and February) and summer (July through September), 5 cull (market) cow slaughter establishments in the United States--west (WE), southeast (SEE), central (CE), north central (NCE), and south central (SCE)--establishments were visited, and cecal-colon contents of cull dairy cows were obtained at the time of slaughter. Samples were examined by microbiologic culture at a single laboratory for Salmonella spp.

RESULTS

Salmonella spp were detected in 23.1% of cecal-colon content samples from cull dairy cows across the 5 slaughter establishments. The highest site prevalence (54.5%) was detected at the WE during the summer period, whereas the lowest was found at the CE during the summer (4.3%) and at the NCE during the winter (4.5%). Considerable variation in the daily prevalence of Salmonella spp was found, particularly at the WE and the SCE. Salmonella spp were isolated from 93% of cecal-colon contents collected on a summer day at the WE.

CONCLUSIONS AND CLINICAL RELEVANCE

Results strongly suggest that there is a high prevalence of Salmonella spp in cull dairy cows at slaughter, which could burden Hazard Analysis Critical Control Point programs implemented in slaughter establishments. Procedures to reduce Salmonella load at the dairy farm and during transport to slaughter could reduce the risk of spread during the slaughter process.

Helical CT angiography in evaluation of live kidney donors

BACKGROUND

Live kidney donor evaluation mandates anatomical and functional assessment of the donor kidney. Helical computed tomography (CT) with advanced 3-D techniques provides detailed description of the vascular, parenchymal, and collecting system.

METHODS

We compared the accuracy of helical CT angiography with intra-operative findings in the evaluation of 102 live kidney donors.

RESULTS

Identification of vascular anomalies was best on direct viewing of the axial images using interactive scrolling through the images and cine-loop paging. In 204 kidneys evaluated, a single renal artery was present in 74.5% and a single renal vein in 87.5%. Multiple renal arteries were more common on the left side (31%) vs the right side (20%). Early branching of the arteries was seen with equal frequency (approximately equal to 10%) on either side. Multiple renal veins were more often on the right side (20%) vs the left side (5%), and one patient was found to have double inferior vena cava. CT angiographic findings were concordant with the intra-operative findings in 97% of the cases, missing a small renal vein, an accessory artery that was visualized in retrospect, and a very early branch that was read as accessory artery. CT also revealed cortical cysts (four cases), duplex collecting system (two cases), hydronephrosis (one case), renal stone (one case), and liver haemangioma (two cases).

CONCLUSION

CT angiography is highly accurate for detecting vascular anomalies, and providing anatomical information. It may serve as the primary tool for donor evaluation.

Flagellin, a novel mediator of Salmonella-induced epithelial activation and systemic inflammation: I kappa B alpha degradation, induction of nitric oxide synthase, induction of proinflammatory mediators, and cardiovascular dysfunction

Gram-negative sepsis is mediated by the actions of proinflammatory genes induced in response to microbes and their products. We report that flagellin, the monomeric subunit of flagella, is a potent proinflammatory species released by Salmonella. Flagellin (1 microgram/ml) induces IkappaBalpha degradation, NF-kappaB nuclear translocation, and inducible NO synthase expression in cultured intestinal epithelial cells (IEC). Aflagellic Salmonella mutants do not induce NF-kappaB activation or NO production by cultured IEC. Antiserum to flagellin blocks NO production in IEC induced by medium conditioned by a variety of motile Gram-negative enteric pathogens (Escherichia coli, Salmonella muenchen, Serratia marcescens, Proteus mirabilis, and Proteus vulgaris). Flagellin, when injected systemically (approximately 10 microgram/mouse), induces systemic inflammation characterized by the systemic expression of a range of proinflammatory cytokines and chemokines and of inducible NO synthase. At higher doses (approximately 300 microgram/mouse), flagellin induces shock, characterized by hypotension, reduced vascular contractility in mice, and death. The effects of flagellin do not diminish in C3H/HeJ LPS-resistant mice, indicating that the Toll-like receptor-4 receptor is not involved in flagellin's actions. In LPS-resistant mice, i.p. injection of S. dublin flagellin or medium conditioned by wild-type S. dublin induces serum IFN-gamma and TNF-alpha, whereas medium conditioned by aflagellic mutants has no effect. Flagellin can be detected in the blood of rats with septic shock induced by live bacteria at approximately 1 microg/ml. We propose that flagellin released by Gram-negative pathogens may contribute to the inflammatory response by an LPS- and Toll-like receptor-4-independent pathway.

Results of preliminary clinical trials of the positron emission mammography system PEM-I: a dedicated breast imaging system producing glucose metabolic images using FDG

Early detection of breast cancer is crucial for efficient and effective treatment. We have developed an instrument for positron emission mammography (PEM) called PEM-I that performs high-resolution metabolic imaging of breast cancer. Images of glucose metabolism are obtained after injection of 75 MBq FDG. The PEM detectors are integrated into a conventional mammography system, allowing acquisition of the emission images immediately after the mammogram, without subject repositioning, and accurate coregistration of images from the 2 modalities. In this article, we present the results of the first clinical pilot study with the instrument.

METHODS

Sixteen subjects (age range, 34-76 y) were studied. All subjects were nondiabetic, nonpregnant, and without a history of cancer. They had recently been found to have suggestive mammography findings or a palpable breast mass and underwent lumpectomy or mastectomy within 2 wk of the study. Results from the PEM study were compared with those from mammography and pathology. A PEM test was classified positive (indicating the presence of cancer) if significant focal uptake was seen in the image or if the counting rate in the breast with suggestive findings was significantly higher than in the contralateral breast.

RESULTS

Of the 16 subjects studied, 14 were evaluable. Ten cancerous tumors and 4 benign tumors were confirmed by pathologic examination after complete removal of the tumor. PEM correctly detected the presence of disease in 8 of 10 subjects. Findings were false-negative in 2 instances and false-positive in none, giving the instrument 80% sensitivity, 100% specificity, and 86% accuracy.

CONCLUSION

Our preliminary results suggest that PEM can offer a noninvasive method for the diagnosis of breast cancer. Metabolic images from PEM contain unique information not available from conventional morphologic imaging techniques and aid in expeditiously establishing the diagnosis of cancer. In all subjects, the PEM images were of diagnostic quality, with an imaging time of 2-5 min.

Positron emission mammographic instrument: initial results

Performance characteristics of a positron emission mammographic (PEM) instrument were studied. This dedicated metabolic breast imaging system has spatial resolution of 2.8-mm full width at half maximum (FWHM), coincidence resolving time of 12-nsec FWHM, and absolute efficiency of 3%. Hot spots with diameter of 16 mm in a phantom with signal-to-background activity ratio of 6:1 were distinguishable with a scanning time of 5 minutes.

Specialty care for patients with epilepsy must become standard of care. Promotion of Specialty Care for Epilepsy Group

Epilepsy is a complex, common disorder with severe consequences for patients. The authors believe that a significant percentage of patients are receiving suboptimal care. The national standard of care needs to be upgraded to include the notion that patients with less than total seizure control or those suffering from any medication side-effects should be given the opportunity to receive specialty care by physicians with specific expertise in the field of epilepsy.

Clustering of trisomy 18 in Kuwait: Genetic predisposition or environmental?

BACKGROUND

This study describes 59 newborns with regular trisomy 18 (EdwardsA centAA syndrome, T18) who were ascertained clinically and cytogenetically at the Kuwait Medical Genetic Centre from 1994 to 1997, out of 118 T18 cases identified from 1980 to 1997.

MATERIALS AND METHODS

T18 cases were ascertained clinically and cytogenetically shortly after birth. In addition to assessing the T18 birth prevalence rate and confidence limits during the years 1994-1997, we investigated the possible etiological factors by a case-control study with normal healthy newborns. Studied factors included gender, parental age, birth order, abortion, clinical variables (presentation, amniotic fluid and mode of delivery), and survival.

RESULTS

The average T18 birth prevalence rate during the period was 8.95 per 10,000 live births (95% confidence limits 6.66-11.23). The T18 cases were mostly females, with a male:female ratio of 1:2.1, and the majority (53%) died before the second week of life. Maternal age above 30 years was found to be a significant factor for T18.

CONCLUSION

This high T18 birth prevalence rate suggests clustering of T18 in the highly inbred population of Kuwait. Such clustering may indicate a possible environmental, and to a lesser extent, genetic predisposition to aneuploidy nondisjunction.

Technique to obtain positron emission mammography images in registration with x-ray mammograms

X-ray mammograms reveal abnormal tissue densities, while metabolic images identify regions of abnormal metabolism. Conventional nuclear medicine and radiologic breast images must be acquired at different times with different patient positions making coregistration difficult. Accurate coregistration of metabolic and x-ray images of the breast is likely to be important when acquiring information about the location and diagnosis of suspicious lesions or tumors. Our PEM-1 (positron emission mammography) system detects metabolic activity within the breast. The two planar detectors are integrated into a conventional x-ray mammography unit. This arrangement simplifies the image registration process by allowing a breast metabolic image to be acquired immediately after performing an x-ray mammogram. The patient is not moved between procedures. A coregistration tool has also been developed. A thin plastic sheet with a wire frame protrudes from the side of the upper PEM detector. With the tool positioned over the suspicious area of the breast, a magnified film density image is made using the available x-ray equipment. A radio-opaque rectangular outline of the wire frame is visible on the film image. During a positron emission metabolic scan, detectors acquire a 49 x 59 mm2 image of the same region. The PEM detectors can be positioned anywhere along the width of the breast. This provides an image of a particular region of interest. Several contiguous images may be combined to provide a complete scan.

Differential promoter usage in prolactin receptor gene expression: hepatocyte nuclear factor 4 binds to and activates the promoter preferentially active in the liver

Characterization of the rat PRL receptor (PRLR) gene has revealed three separate untranslated exon 1 sequences, each associated with a different transcription start site and 5'-flanking sequence. We show by RT-PCR that exon 1A is expressed primarily in liver but is also detectable in ovary and mammary gland. Exon 1B expression is observed exclusively in the ovary, whereas exon 1C is expressed in all three tissues. Transient transfection of luciferase reporter constructs containing parts of the 5'-flanking regions (0.3-1.1 kb) of exon 1A, 1B, and 1C, respectively, showed activity of the 1A promoter in Chinese hamster ovary (CHO) cells, the human hepatoma cell line, HepG2, and the rat hepatoma cell line, H4II, which was 10- to 14-fold increased compared with the activity of the promoter-less luciferase vector. No activity of the 1A promoter was detected in the human mammary cell line, T-47D. Relative to a vector containing the Simian virus 40 (SV40) promoter, the 1A promoter had 20% activity in H4II cells and 1-3% activity in CHO and HepG2 cells. The 1B promoter produced a 6.1-fold increase of luciferase activity in CHO cells (approximately 2% of the SV40 promoter), whereas no significant activity was detected in HepG2, H4II, and T-47D cells. The 1C promoter was strongly active in T-47D cells (approximately 64-fold over control) and moderately active in the other cell lines tested (9- to 13-fold over control). 5'-Deletion analysis of the 1A promoter revealed that a fragment containing -83/ +81 bp, relative to the transcription start site, was sufficient to drive transcription in hepatoma cells, whereas this construct was inactive in CHO cells. Cotransfection of CHO cells with the -83/+81 construct and an expression vector encoding the liver-enriched transcription factor, hepatocyte nuclear factor 4 (HNF4), revealed a dose-dependent transactivation of the proximal 1A promoter with a maximal stimulation of approximately 10-fold. Electrophoretic mobility shift assays showed binding of HNF4 to the sequence -14/+24 of the 1A promoter, and mutational analysis revealed that the sequence GGGCAAAGTCA at position +11/+21 is required for this binding. We conclude that the 1A, 1B, and 1C promoters of the PRLR gene are used in a cell type- dependent way that may play a role in differential hormonal regulation of the gene. In particular, we have shown that HNF4 operates on the proximal 1A promoter and may be responsible, in combination with other factors, for the increased activity of this promoter in adult female liver.

Characterization of crystals of the thermostable DNA polymerase I from Thermus aquaticus

Thermus aquaticus DNA polymerase I is an enzyme that is of both physiological and technological interest. It carries out template-directed polymerization of DNA at elevated temperatures and is widely used in polymerase chain reaction (PCR). We have obtained crystals of the enzyme that diffracts X-rays to at least 3.0 A resolution in a cubic space group. Determination of the three-dimensional structure of the native enzyme along with those of relevant complexes will greatly enhance our knowledge of molecular events involved in DNA replication, will permit improvements in PCR, and will add to our knowledge of the structural bases of thermostability in proteins.

Comparative genotoxicity of 2,3'-O-cyclocytidine, beta-xylocytidine and 1-beta-D-arabinofuranosylcytosine in human tumor cell lines

We have investigated the genotoxicity of two 3'-derivatives of cytidine, 2,3'-O-cyclocytidine (3'-cycloC) and beta-xylocytidine (xyloC), in human leukemia and solid tumor cell lines. Both derivatives were found to be cytotoxic at micromolar concentrations. For example, in the alveolar tumor cell line A549 which was included in all experiments as a reference, drug concentrations required to induce 50% inhibition of cell growth (D50 values) equalled 55 microM for 3'-cycloC and 80 microM for xyloC. Compared with the response of this reference cell line, none of the solid tumor cell lines tested--representing five different malignancies--displayed significant hypersensitivity to these drugs, while the acute lymphoblastic leukemia cell lines proved to be hypersensitive (range of D50 values, 5-13 microM). To gain insight into the modes of cytotoxic action of xyloC and 3'-cycloC, we compared the effect on DNA metabolism of these compounds with that of 1-beta-D-arabinofuranosylcytosine (araC), a potent inhibitor of semi-conservative DNA replication and long-patch excision repair. As seen with araC, the xylo compound strongly inhibited both DNA replicative synthesis and the repair of DNA damage induced by UV light and 60Co gamma-radiation. In gamma-irradiated A549 cells, the extent of repair inhibition by 1 mM xyloC was approximately 40% of that inhibited by araC, and concomitant exposure of the irradiated cultures to xyloC plus araC gave rise to a synergistic response. Since araC was employed at a concentration (0.1 mM) which produced a maximal effect on DNA repair when applied alone, the observed synergistic response implies that the mode of action of xyloC on DNA repair is different from that of araC. In contrast to that observed with xyloC, 3'-cycloC proved to be a very weak inhibitor of DNA replication and repair, strongly suggesting that the genotoxic action of the latter analog may be through a mechanism other than inhibition of DNA synthesis.

Feasibility study for positron emission mammography

A feasibility study is presented for a small, low-cost, dedicated device for positron emission mammography. Two detector arrays above and below the breast would be placed in a conventional mammography unit. These detectors are sensitive to positron annihilation radiation, and are connected to a coincidence circuit and a multiplane image memory. Images of the distribution of positron-emitting isotope are obtained in real time by incrementing the memory location at the intersection of each line of response. Monte Carlo simulations of a breast phantom are compared with actual scans of this phantom in a conventional PET scanner. The simulations and experimental data are used to predict the performance of the proposed system. Spatial resolution experiments using very narrow bismuth germanate BGO crystals suggest that spatial resolutions of about 2 mm should be possible. The efficiency of the proposed device is about ten times that of a conventional brain scanner. The scatter fraction is greater, but the scattered radiation has a very flat distribution. By designing the device to fit in an existing mammography unit, conventional mammograms can be taken after the injection of the radio-pharmaceutical allowing exact registration of the emission and conventional mammographic images.

Effect of fluoride dentifrices on salivary fluoride levels in children

Fluoride dentifrices are well accepted for their caries preventive effects. The fluoride concentration in the oral fluids after tooth brushing with fluoride dentifrices may have an important relationship to the caries reducing capacity. The present study was aimed to clinically evaluate the salivary fluoride retention of dentifrices containing low fluoride concentration in 50 children, aged 7-9 years before, during and after the use of fluoride toothpaste. Estimation of fluoride in saliva was done using a Orion microprocessor ion analyser with a fluoride specific ion electrode. The results of the present study suggest that there is considerable salivary fluoride retention after brushing with fluoride dentifrices. The retention of fluoride in the saliva at a higher level even with the low fluoride concentration, proves the similar cariostatic effect as of higher concentration.

Hypernatraemic dehydration in the Hail region of Saudi Arabia

Infants presenting with hypernatraemic dehydration were studied prospectively in order to describe its incidence and the predisposing factors. Five hundred and twenty children with gastroenteritis were admitted to the Paediatric Unit of Hail General Hospital over a 1-year period from 1 June 1985 to 1 June 1986. Twenty-five children (4.8%) had hypernatraemia (Na+ greater than 150 mmol/l) and all 25 were under 1 year of age, 23 (92%) being under 6 months. Twenty (80%) came from families living in the villages and had a poor educational background. All the babies were bottle-fed. The majority of the mothers did not know how to prepare food hygienically and with the appropriate water/milk proportions. Most of the infants presented with high fever (+39 degrees C) and the majority were underweight for their age. Two babies died and one had evidence of neurological damage. This study indicates that the incidence of hypernatraemic dehydration is significant in this region and causes serious morbidity and mortality. It confirms the importance of breast-feeding and the need to educate the public in the proper preparation of bottle feeds when breast-feeding is not possible.