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Banana lectin is unique in its recognition of the reducing unit of 3-O-beta-glucosyl/mannosyl disaccharides: a calorimetric study.

The binding of banana lectin (BanLec) to laminaribiose (Glcbeta1,3Glc) and a series of novel synthetic analogues was measured by titration calorimetry to assess the contribution of the hydroxyl groups of the reducing glycosyl moiety and its 3-O-beta-substituent to binding. Key areas of interaction involved the 1, 2, and 6 positions of the reducing-terminal hexose unit. The alpha-anomeric configuration of the reducing hexose was strongly favored over the beta-anomer. The 2-hydroxyl in the axial position (mannose) also enhanced binding, whereas the 6-hydroxymethyl group was essential, because xylopyranose in the reducing position was inactive. The 3-O-beta-glucosyl unit of methyl alpha-laminaribioside could be replaced by any of its monodeoxy derivatives. However, the 4'-deoxy derivative or axial hydroxy (galactosyl) substitution was somewhat detrimental to binding. 3-O-substitution with the (S)tetrahydropyranyl ring or a benzyl group had similar effect as 4'-deoxyglucosyl substitution. Surprisingly, p-nitrobenzyl or beta-xylosyl 3-O-substitution greatly enhanced binding of the reducing glucosyl or mannosyl derivative. Chemical syntheses of a number of novel disaccharides and analogues prepared for this study are described.

Calorimetry↗

Crystal structure of banana lectin reveals a novel second sugar binding site.

Banana lectin (Banlec) is a dimeric plant lectin from the jacalin-related lectin family. Banlec belongs to a subgroup of this family that binds to glucose/mannose, but is unique in recognizing internal alpha1,3 linkages as well as beta1,3 linkages at the reducing termini. Here we present the crystal structures of Banlec alone and with laminaribiose (LAM) (Glcbeta1, 3Glc) and Xyl-beta1,3-Man-alpha-O-Methyl. The structure of Banlec has a beta-prism-I fold, similar to other family members, but differs from them in its mode of sugar binding. The reducing unit of the sugar is inserted into the binding site causing the second saccharide unit to be placed in the opposite orientation compared with the other ligand-bound structures of family members. More importantly, our structures reveal the presence of a second sugar binding site that has not been previously reported in the literature. The residues involved in the second site are common to other lectins in this family, potentially signaling a new group of mannose-specific jacalin-related lectins (mJRL) with two sugar binding sites.

Amino Acid Sequence↗

Successful pregnancy outcome following Tompkins metroplasty done early in pregnancy.

A hysterosalpingogram revealed a septate uterus in a 29 year old nulliparous woman with a history of recurrent pregnancy loss. The patient underwent Tompkins metroplasty in the proliferative phase of the menstrual cycle. One month after the operation she presented with a delay in her menses and a positive pregnancy test. Ultrasound revealed a viable fetus commensurate with 10 weeks gestation, making the gestation period 5 weeks at the time of surgery. After reviewing the patient's menstrual history it was found that the period the patient had before surgery was on time but with unusually minimal bleeding. A repeat ultrasound scan for anomaly done 7 weeks later was commensurate with 17 weeks gestation. The patient carried her pregnancy for the first time until approximately 37 weeks when she delivered by Caesarean section a healthy female baby weighing 3700 g.

Abortion, Habitual↗

Failure of fertilization after intracytoplasmic sperm injection in a patient with Kartagener's syndrome and totally immotile spermatozoa: case report.

Patients with Kartagener's syndrome (KS) are invariably infertile with totally immotile spermatozoa. Intracytoplasmic sperm injection (ICSI) is considered to be the treatment of choice for patients with immotile spermatozoa. We report the second KS case in the literature from whom immotile spermatozoa from the ejaculate failed to fertilize mature oocytes after ICSI. The role of micromanipulation in the treatment of KS patients is discussed.

Adult↗

Assessment of reliability of microarray data and estimation of signal thresholds using mixture modeling.

DNA microarray is an important tool for the study of gene activities but the resultant data consisting of thousands of points are error-prone. A serious limitation in microarray analysis is the unreliability of the data generated from low signal intensities. Such data may produce erroneous gene expression ratios and cause unnecessary validation or post-analysis follow-up tasks. In this study, we describe an approach based on normal mixture modeling for determining optimal signal intensity thresholds to identify reliable measurements of the microarray elements and subsequently eliminate false expression ratios. We used univariate and bivariate mixture modeling to segregate the microarray data into two classes, low signal intensity and reliable signal intensity populations, and applied Bayesian decision theory to find the optimal signal thresholds. The bivariate analysis approach was found to be more accurate than the univariate approach; both approaches were superior to a conventional method when validated against a reference set of biological data that consisted of true and false gene expression data. Elimination of unreliable signal intensities in microarray data should contribute to the quality of microarray data including reproducibility and reliability of gene expression ratios.

Algorithms↗

tRNA-linked molecular beacons for imaging mRNAs in the cytoplasm of living cells.

When oligonucleotide probes are microinjected into cells to image the distribution of RNAs, they are rapidly sequestered into the nucleus. As a result, it is difficult to detect mRNAs in the cytoplasm of living cells. We were able to overcome this process by attaching tRNA transcripts to the probes. We show that when fluorescently labeled tRNAs, tRNAs with extensions at their 5' end, or chimeric molecules in which a molecular beacon possessing a 2'-O-methylribonucleotide backbone is linked to a tRNA, are injected into the nucleus of HeLa cells, they are exported into the cytoplasm. When these constructs are introduced into the cytoplasm, they remain cytoplasmic. These constructs allow the distribution of both the general mRNA population and specific mRNAs to be imaged in living cells. This strategy should also be useful for enhancing the efficacy of antisense oligonucleotides by keeping them in the cytoplasm. Our observations show that the fidelity of the tRNA export system is relaxed for unnatural tRNA variants when they are introduced into the nucleus in large amounts.

Active Transport, Cell Nucleus↗

Morphological assessment of polycystic ovary using transvaginal ultrasound.

A total of 104 patients with bilateral polycystic ovaries (PCO) diagnosed by transvaginal ultrasound were classified into four groups (A < 5 cysts, B 5-10 cysts, C > 10 cysts located under ovarian capsule, D numerous cysts distributed all over the ovary) according to the number of microcysts. Ovarian volume, clinical features (menstrual disturbance, obesity and hirsutism), endocrine levels [luteinizing hormone (LH), LH/follicle stimulating hormone ratio, testosterone, androstenedione and dehydroepiandrosterone-sulphate] and response to clomiphene were compared for each group and 17 control subjects with normal ovulatory cycles. Ovarian volume in PCO subjects was significantly larger than that in control subjects. As the number of microcysts increased, the ovarian volume enlarged and the endocrine abnormality worsened. All endocrine parameters in PCO subjects with menstrual disturbances were significantly higher than those in PCO subjects without menstrual disturbances and controls. In PCO subjects without menstrual disturbances only androstenedione was significantly higher than in controls. Among PCO subjects, the frequency of menstrual disturbances, the percentage of response to clomiphene and the pregnancy rate in groups C and D were significantly higher than in groups A and B. Therefore, screening the ovaries in infertile patients by means of transvaginal ultrasound and subsequent assessment of morphology in PCO may suggest endocrine abnormality and help in selecting the proper treatment.

Adult↗

Transvaginal ultrasound imaging, histopathology and endocrinopathy in patients with polycystic ovarian syndrome.

In order to investigate the pathological characteristics of polycystic ovaries diagnosed by transvaginal ultrasound (TVS) in patients with polycystic ovarian syndrome (PCOS) and to investigate the relationship between morphological and endocrine changes in the ovaries, 32 PCOS patients with bilateral polycystic ovaries (> 10 cysts) detected by TVS were studied; 20 ovulatory women served as controls. Ovarian tissues from wedge resection were examined histologically. A comparative histological and TVS study of ovarian morphology was made, and the relationship between the number of small cysts and the endocrine profile was examined. The position and size of small cysts on TVS agreed with those observed histologically. There was a significant correlation between the number of small cysts on TVS and the number of atretic follicles with hypertrophied and luteinized inner theca cells, and thickened ovarian capsules. Numerous atretic follicles and thickened ovarian capsules were observed in 97 and 64% of ovaries respectively, from PCOS patients. In patients with PCOS, a significant positive correlation was noted both between the number of small cysts and delta 4-androstenedione (ASD), and between ASD and the luteinizing hormone/follicle-stimulating hormone (LH/FSH) ratio. Furthermore, testosterone, ASD and the number of small cysts on TVS were significantly higher in PCOS patients with ovarian thickened tunica compared to PCOS patients without ovarian thickened tunica. TVS images of ovaries in patients with PCOS correlated with the histopathological and endocrine features. It is suggested that an increase in intra-ovarian small cysts leads to increased production of ovarian androgen, in turn influencing the secretion of gonadotrophin, and is correlated with ovarian capsular thickness.

Adult↗

Suppressed expression of the urea cycle enzyme genes in the liver of carnitine-deficient juvenile visceral steatosis (JVS) mice in infancy and during starvation in adulthood.

Systemic carnitine-deficient juvenile visceral steatosis (JVS) mice exhibit decreased expression of some liver-selective genes including those for the urea cycle enzymes during the infantile period. At 25 days, carbamoylphosphate synthetase (CPS) mRNA level was remarkably low in the liver of JVS mice, and the HNF-4 and C/EBP-alpha mRNA contents were also reduced. HNF-3 alpha and C/EBP-beta mRNAs were slightly higher in the liver of JVS mice, and HNF-1 mRNA remained normal. These results, together with the developmental changes of these transcription factor mRNA levels, suggest that HNF-4 and C/EBP-alpha are involved in the suppression of CPS expression. If JVS mice survived the crisis at 4-5 weeks, their body weight caught up with that of control mice around 7 weeks. The steady-state levels of CPS and argininosuccinate synthetase (ASS) mRNAs in the liver of JVS mice were normalized by no later than 8 weeks. Starvation for 48 h caused an increase of about twofold in CPS and ASS mRNA levels in the liver of control mice, while the same treatment failed to increase their levels in the liver of JVS mice. The starvation similarly caused increases in HNF-4 and C/EBP-beta mRNA levels in the liver of both control and JVS mice, but the increases were significantly less in JVS mice than in control mice. Thus, the lack of induction of CPS and ASS mRNAs during development and under starvation in JVS mice correlated with the lower induction of HNF-4 and C/EBP-alpha mRNAs, and of HNF-4 and C/ EBP-beta mRNAs, respectively. Furthermore, all these changes seemed to correlate with the presence of fatty liver and the high serum free fatty acid levels, suggesting that disturbance of fatty acid metabolism affects nitrogen metabolism at least in part via altered gene expression of transcription factors such as HNF-4, C/EBP-alpha, and C/EBP-beta.

Age Factors↗

Assessment of gamma dose rate over a suspected uranium mineralisation area of Jebel Mun, Western Sudan.

This study was conducted at the request of authorities in western Darfour State, to address the public concern about the levels of radioactivity in the area of Jebel Mun situated at Sudan-Chad international boundaries. It has been identified as a high background radiation area through aerial geological surveys conducted in late 1970s. The ambient gamma dose in the area was measured with the aid of a hand-held dose rate meter (Mini-Rad, Series 1000) and the surface rock samples were collected and analysed for their radioactivity content using a high-resolution gamma spectrometry equipped with HPGe with relative efficiency of 18%. The activity concentrations of 238U, 232Th and 40K were found to range from 39-253 Bq.kg(-1), 41-527 Bq.kg(-1) and 77-3027 Bq.kg(-1), respectively. From the values of the standard deviation it was concluded that the activity concentration of the considered primordial radionuclides was highly scattered (localised) which in turn indicates non-uniformity in the geological features and/or formations. 238U activity concentration corresponds to equivalent mass concentration of 7.77+/-6.12 ppm (3.19-20.73 ppm), which is of no economic importance. Samples are enriched in thorium relative to uranium as reflected by the Th:U mass ratio which ranges from 3 to 17. The absorbed dose rate in air as estimated from the measured activity concentrations of the primordial radionuclides using the DRCFs (dose rate conversion factors) falls within the range of 70-522 nGy.h(-1) with an average of 221+/-130 nGy.h(-1). It corresponds to an annual effective dose equivalent averaged of 0.27 mSv. The regression analysis has shown that the correlation between calculated and the measured ambient dose rate is marginally significant (r2 = 0.59). The 232Th series is the major producer of the surface radioactivity followed by 40K as they contribute 48% and 32% of the total absorbed dose, respectively.

Environmental Exposure↗

Haemophilus type B meningitis in Saudi children under 5 years old.

This study was designed to determine the magnitude of bacterial meningitis in general and Hib meningitis in particular among children below the age of 5 years. A population-based, prospective descriptive and analytical study was conducted in five regions, one each in northern, southern, eastern, western, and central parts of Saudi Arabia. Active surveillance for cases of bacterial meningitis among the study population, which comprised 171,818 children under 5 years of age, was implemented. A total of 208 cases of meningitis were identified, of which 141 (67.8 per cent) were identified with a definite causative organism. The remaining 67 cases (32 per cent) were labeled as aseptic meningitis. The overall incidence of meningitis was 60.53/10(5) in under-fives with a disease spectrum similar to that reported in studies conducted in other countries. The three leading causes of meningitis were Hib (Haemophilus influenzae type B), MCM (Neisseria menigitides) and SPN (Streptococcus pneumoniae). Hib meningitis constituted 28 per cent of cases with an incidence rate of 16.88/10(5) children. There was a marked regional variation in Hib incidence. MCM was the second leading cause (18 per cent) of meningitis with an incidence of 10.77/10(5) while SPN comprised 11 per cent of cases and its incidence was 9.69/10(5). Almost all MCM cases were related to meningitis outbreaks that occurred in Saudi Arabia during two successive Hajj seasons (2000-2001). Hib cases showed a bimodal seasonality, one peak during March-May, the other during September-November. The fact that this study is the first national base-line data on meningitis in general and Hib incidence in particular, has augmented further justification for introducing Hib vaccine within the national Expanded Program on Immunization (EPI). Based on the experience gained during this study regarding surveillance of meningitis disease, optimal methods to strengthen meningitis surveillance were identified. A model of Meningitis Diseases Surveillance was generated that can be tested and then generalized. The study has documented beyond doubt the impact of Hajj seasons on MCM disease occurrence and further justifies the rigorous control and preventive measures being taken in this aspect.

Child, Preschool↗

Retrospective measles outbreak investigation: Sudan, 2004.

Recent population-based studies of measles incidence and deaths in Sudan are not available. To determine the epidemiology and case-fatality rate (CFR) of measles, we conducted a retrospective outbreak investigation in two states in northern Sudan. Of 1144 case-patients identified, 92% were <15 years; 48.6% were vaccinated; and 62% received vitamin A before illness. Ten measles-associated deaths were identified (CFR 0.9%; 95% confidence interval 0.16-1.91). CFR determined by this investigation is lower than expected for the region but remains 10 times higher than that in developed countries. Measles control should be strengthened by improving vaccine coverage, measles surveillance and case-management.

Adolescent↗

Evidence that aquaporin 1 is a major pathway for CO2 transport across the human erythrocyte membrane.

We report here the application of a previously described method to directly determine the CO2 permeability (P(CO2)) of the cell membranes of normal human red blood cells (RBCs) vs. those deficient in aquaporin 1 (AQP1), as well as AQP1-expressing Xenopus laevis oocytes. This method measures the exchange of (18)O between CO2, HCO3(-), and H2O in cell suspensions. In addition, we measure the alkaline surface pH (pH(S)) transients caused by the dominant effect of entry of CO2 vs. HCO3(-) into oocytes exposed to step increases in [CO2]. We report that 1) AQP1 constitutes the major pathway for molecular CO2 in human RBCs; lack of AQP1 reduces P(CO2) from the normal value of 0.15 +/- 0.08 (SD; n=85) cm/s by 60% to 0.06 cm/s. Expression of AQP1 in oocytes increases P(CO2) 2-fold and doubles the alkaline pH(S) gradient. 2) pCMBS, an inhibitor of the AQP1 water channel, reduces P(CO2) of RBCs solely by action on AQP1 as it has no effect in AQP1-deficient RBCs. 3) P(CO2) determinations of RBCs and pH(S) measurements of oocytes indicate that DIDS inhibits the CO2 pathway of AQP1 by half. 4) RBCs have at least one other DIDS-sensitive pathway for CO2. We conclude that AQP1 is responsible for 60% of the high P(CO2) of red cells and that another, so far unidentified, CO2 pathway is present in this membrane that may account for at least 30% of total P(CO2).

Animals↗

Effect of the administration of recombinant activated factor VII (rFVIIa; NovoSeven) in the management of severe uncontrolled bleeding in patients undergoing heart valve replacement surgery.

Recombinant activated factor VII (rFVIIa; NovoSeven, Novo Nordisk A/S, Bagsvaerd, Denmark) is being increasingly used to secure haemostasis in difficult clinical situations. The role of rFVIIa in the treatment of patients undergoing open-heart surgery for valvular heart disease was evaluated in an open pilot study. Study objectives included evaluation of blood loss, haemostatic effect and safety and laboratory parameters following rFVIIa administration. To date, we have treated five patients (one child aged 2.5 years and four adults) undergoing surgical procedures including arterial switch, closure of atrial septal defect and De Vega's procedure (mitral valve replacement with tricuspid valve repair). Four patients received rFVIIa intraoperatively, while the fifth received it postoperatively. Satisfactory haemostasis was achieved with a single dose (30 microg/kg) of rFVIIa. Four hours after treatment mean blood loss was 262.5 ml for adults (220-334 ml) and 85 ml for the child. No significant adverse events were reported. Laboratory parameters indicated a mean 18.5-fold (range 3.7-42) increase in FVII levels at 30 min postinjection and a mean reduction of 12 s (range 3-39 s) in prothrombin time. In conclusion, rFVIIa represents an effective and well-tolerated treatment for serious bleeding episodes both during cardiac surgery and postoperatively.

Adult↗

Gender differences in interpupillary distance among Arabs.

Information about the normal values of interpupillary distance (IPD) for a particular age group, sex, and ethnic background has important clinical implications. Normative values of IPD could be useful in the diagnosis of certain syndromes and also in surgery after facial trauma. Our main reason for carrying out this study was to provide normal values and ranges of IPD for the male Arab population. The distance between the temporal limbus of one eye and the nasal limbus of the other was measured by a ruler. We have provided average values and range of values of normal IPD for Arab boys, young adults, and older adults. Arab males have IPD on the average 2.0 mm wider than females. Different experimental techniques and ages of subjects make conclusive statements about the ethnic variation of IPD difficult.

Adolescent↗

Haemophilus influenzae meningitis in Malaysia.

OBJECTIVE: To determine the pattern of postneonatal childhood meningitis in Malaysia. METHODS: Retrospective cross-sectional study involving five pediatric departments in Malaysia. RESULTS: There were 435 cases of clinical meningitis admitted to the five centers. More than 90% of the patients were <5 years old, and one-half were <6 months of age. The estimated overall incidence of childhood meningitis in the first 5 years of life was 76.7 per 100000 per year. However, of the 435 cases only 71 (16.3%) fulfilled laboratory diagnostic criteria and in only 58 of these was an organism isolated. Nearly one-half (48%) of all bacteriologically proved cases were caused by Haemophilus influenzae type b (Hib). The mortality rate was 12.5% and 21 patients (30%) suffered neurologic sequelae. CONCLUSIONS: More than one-half of all cases of culture-positive childhood bacterial meningitis were caused by Hib, although successful isolation of a pathogen occurred in only a small proportion of cases. For this reason the true incidence of Hib meningitis in Malaysia remains unknown. These findings are consistent with previous studies in Malaysia.

Child↗