IsK and KvLQT1: mutation in either of the two subunits of the slow component of the delayed rectifier potassium channel can cause Jervell and Lange-Nielsen syndrome

The Jervell and Lange-Nielsen syndrome (JLNS) comprises profound congenital sensorineural deafness associated with syncopal episodes. These are caused by ventricular arrhythmias secondary to abnormal repolarisation, manifested by a prolonged QT interval on the electrocardiogram. Recently, in families with JLNS, Neyroud et al. reported homozygosity for a single mutation in KVLQT1 , a gene which has previously been shown to be mutated in families with dominantly inherited isolated long QT syndrome [Neyroud et al . (1997) Nature Genet ., 15, 186-189]. We have analysed a group of families with JLNS and shown that the majority are consistent with mutation at this locus: five families of differing ethnic backgrounds were homozygous by descent for markers close to the KVLQT1 gene and a further three families from the same geographical region were shown to be homozygous for a common haplotype and to have the same homozygous mutation of the KVLQT1 gene. However, analysis of a single small consanguineous family excluded linkage to the KVLQT1 gene, establishing genetic heterogeneity in JLNS. The affected children in this family were homozygous by descent for markers on chromosome 21, in a region containing the gene IsK . This codes for a transmembrane protein known to associate with KVLQT1 to form the slow component of the delayed rectifier potassium channel. Sequencing of the affected boys showed a homozygous mutation, demonstrating that mutation in the IsK gene may be a rare cause of JLNS and that an indistinguishable phenotype can arise from mutations in either of the two interacting molecules.     

Patient preference for self-collected cultures for group B streptococcus in pregnancy

The purpose of this study was to examine the factors which affect the level of fatigue among patients participating in clinical trials in which this symptom had been assessed with the EORTC QLQ-C30. Data were assembled from 2390 patients in ten clinical trials in which the QLQ-C30 had been used to assess baseline and on-study quality of life. The relationship between the level of fatigue reported by the patients on the fatigue scale of this questionnaire and patient and disease characteristics was assessed in univariate and multivariate cross-sectional analyses. In addition, changes in fatigue scores were compared in a longitudinal analysis among patients on two arms of an anti-emetic trial whose emesis control was markedly different. Baseline fatigue levels differed substantially among patients taking part in the different trials. Factors associated with greater fatigue severity on univariate analysis included: female gender, presence of metastatic disease, and poorer performance status. In addition, on multivariate analyses the oldest patients were found to have less fatigue, as were patients with breast cancer, while patients with ovarian and lung cancer experienced greater fatigue. Patients on the arm of the anti-emetic trial in which emesis was better controlled showed significantly less increase in fatigue after receiving chemotherapy. The fatigue scale of the QLQ-C30 appears to provide a useful approach to assessing this important symptom. The relationships found between fatigue and patient and disease characteristics need further exploration as does the degree to which the QLQ-C30 fully captures this dimension of quality of life.     

Cloning, tissue expression, and chromosomal localization of the mouse IRS-3 gene

Insulin receptor substrate (IRS) proteins are key regulators of basic functions such as cellular growth and metabolism. They provide an interface between multiple receptors and a complex network of intracellular signaling molecules. Two members of this family (IRS-1 and IRS-2) have been identified previously. In this investigation, we analyzed a mouse expressed sequence tag clone that proved to be a new member of the IRS family. Sequence analysis of this clone and comparison with the sequences deposited in GenBank demonstrates this protein may be the murine homolog of rat IRS-3, recently purified and cloned from rat adipocytes. Accordingly, we have named our protein mouse IRS-3. The expressed sequence tag clone contains the complete coding sequence of 1485 bp, encoding a protein of 495 amino acids. Sequence alignment with the other members of the IRS family shows that this protein contains pleckstrin homology and phosphotyrosine-binding domains that are highly conserved. In addition, there is conservation of many tyrosine phosphorylation motifs responsible for interactions with downstream signaling molecules containing SH2 domains. The murine IRS-3 messenger RNA (2.4 kilobases in length) is expressed in many tissues, with highest levels in liver and lung. Mouse IRS-3 is highly expressed in the first part of the embryonic life, when IRS-1 messenger RNA is barely detectable. Unlike the genes encoding IRS-1 and IRS-2, the IRS-3 gene contains an intron (344 bp in length) in the region between the pleckstrin homology and the phosphotyrosine-binding domains. Fluorescent in situ hybridization localized the mouse IRS-3 gene on the telomeric region of chromosome 5G2. Cloning of the murine IRS-3 gene will make it possible to apply genetic approaches to elucidate the physiological role of this new member of the IRS family of proteins.     

The inactivated plasmid inititator protein RepC/RepC* may have a regulatory role

During replication of the plasmid pT181, the initiator protein RepC is modified by the addition of an oligodeoxynucleotide, giving rise to a new form, RepC*. Here we show that during in vitro replication, RepC* is radioactively labeled, suggesting that the source of the RepC* oligodeoxynucleotide is the newly synthesized pT181 DNA. The RepC/RepC* heterodimer retains its ability to bind the pT181 double-strand origin and, therefore, it may act as a competitive inhibitor of the RepC homodimer during replication.     

Antigenic variants of Plasmodium chabaudi chabaudi AS and the effects of mosquito transmission

Previous results, using a passive transfer assay, have shown that recrudescences of Plasmodium chabaudi chabaudi AS strain are antigenically different from the infecting parental population and also that the recrudescence appears to be a mix of antigenic types. This present study examines further these recrudescent populations using an indirect fluorescent antibody test on live, schizont-infected red blood cells. This analysis shows that ten clones derived from a recrudescence are all antigenically different from the parent population and that some are different from each other. The use of this method to examine the antigenic types of recrudescent clones after transmission through mosquitoes also demonstrates a resulting change in antigenicity. Such results showing a link between mosquito transmission and varying antigenicity may have important implications in terms of immunity and vaccine development.     

Activation of 5-HT2 receptors facilitates depolarization of neocortical neurons by N-methyl-D-aspartate

We prospectively studied 63 children with transient hyperglycemia to determine their risk of acquiring insulin-dependent diabetes mellitus (IDDM) and to evaluate the predictive value of immunologic markers of prediabetes and of the intravenous glucose tolerance test. Children with transient hyperglycemia were identified by a prospective systematic review of the laboratory reports of a large children's hospital and an office-based pediatric practice and by referral from pediatricians. Transient hyperglycemia occurred in 0.46% of children seen in the children's hospital and in 0.013% of children attending a pediatric office practice. Insulin-dependent diabetes mellitus developed within 18 months of identification in 32% of children in whom transient hyperglycemia was discovered in the absence of a serious illness, compared with 2.3% of children identified during a serious illness (relative risk, 13.9; 95% confidence interval, 1.56 to 123.5). Islet cell antibodies and competitive insulin autoantibodies each had a 100% positive predictive value for IDDM; the negative predictive value of islet cell antibodies and competitive insulin autoantibodies was 96% and 98%, respectively. The stimulated insulin release during an intravenous glucose tolerance test, adjusted for age, had the highest overall accuracy of prediction. All children less than 6 years of age with stimulated insulin release levels < 85 pmol/L (12 microU/ml) subsequently had IDDM, as did an 11-year-old child whose stimulated insulin release level was below the 1st percentile of 170 pmol/L (24 microU/ml). To date, no child whose stimulated insulin release level was above the 5th percentile has had IDDM. We conclude that when transient hyperglycemia occurs during a serious intercurrent illness, the risk of progression to IDDM is low. In contrast, one third of children in whom transient hyperglycemia is identified without a serious illness can be expected to have IDDM within 1 year. A combination of islet cell antibodies, competitive insulin autoantibodies, and stimulated insulin release levels during an intravenous glucose tolerance test can accurately distinguish children with prediabetes from those with presumed benign transient increases in plasma glucose concentrations.     

Thermally-induced changes in the metabolism of the eye of the crayfish Paranephrops planifrons: respiration and substrate utilization at three distinct temperatures

Gleason's score (GS) has been reported to be the most valuable prognostic factor in cases of prostate cancer. GS is solely dependent on the histological architecture of the prostate cancer, but, it seems doubtful that histological patterns are sufficient for evaluating the degree of malignancy of prostate cancer. We previously reported that the estimation of volume-weighted mean nuclear volume (MNV) might be a more useful prognosticator for prostate cancer than subjective histological grading. However, the previous study was conducted on patients treated in a single hospital, and the number of subjects was too small to draw a definitive conclusion. In this study, we analyzed a larger number of subjects at another institution using a blinded study design. A retrospective prognostic study of 195 patients with prostate cancer diagnosed between January 1966 and December 1988 at Kyoto University Hospital, and treated by conservative therapy, was conducted. Unbiased estimates of MNV were compared with the clinical stage and histological grading according to GS with regard to the prognostic value. Univariate analysis revealed that estimates of MNV, clinical stage, and GS all correlated significantly with disease-specific survival in cases of prostate cancer. Multivariate analysis of all cases also revealed that all of these factors were significant independent prognosticators of disease-specific survival. However, focusing on clinically localized cases (stages A, B, and C), multivariate analysis revealed that the estimation of MNV was the only powerful prognosticator of prostate cancer. This study indicates that the estimation of MNV is prognostically equal or superior to GS in cases of prostate cancer. We emphasized that the estimates of MNV is a more objective method for histological grading to predict the malignant potential of prostate cancer.     

Purification and characterization of a human bradykinin binding protein from inflammatory cells

Bradykinin (BK) is a potent mediator with a broad spectrum of pharmacological and inflammatory actions which are exerted through cell surface receptors. We report here the affinity chromatographic purification of a novel 14 kDa BK binding protein from human blood neutrophils and also peripheral blood mononuclear cells (PBMC), 80% of which are lymphocytes. Radioreceptor crosslinking experiments using bifunctional crosslinkers and radiolabelled BK identified a 14 kDa protein in these cell types both on the cell surface, in glycerol purified plasma membranes and in detergent solubilized cell extracts. Purification by BK affinity chromatography from a variety of BK responsive human cell types i.e. CCD-16Lu lung fibroblasts, HL60 promyelocytes, U937 myelomonocytes and Jurkat T lymphocytes also demonstrated a 14 kDa protein. Purified material obtained from three different BK affinity columns all demonstrated three major proteins at 190, 50 and 14 kDa when eluted with either excess BK or mild acid. Neutrophil fractions from detergent solubilized cell extracts contained an additional 150 kDa protein when eluted with mild acid. Neutrophil and PBMC crude plasma membrane BK affinity column purifications yielded only a single 14 kDa protein. Radioreceptor dot assays of the purified neutrophil eluates containing the 14 kDa protein revealed specific binding to [125I]-BK with a 160 fold excess signal ratio over the original membrane extract. Our data indicates that we have successfully isolated a 14 kDa novel human BK specific binding protein expressed on the surface of inflammatory cells.     

Zidovudine pharmacokinetics in premature infants exposed to human immunodeficiency virus

We used population analysis techniques to determine zidovudine (ZDV) pharmacokinetic parameters in 15 preterm neonates (mean gestational age, 29.4 weeks; mean birth weight, 1,230 g) at a mean age of 5.5 days. The values of the pharmacokinetic parameters were as follows: clearance, 2.53 +/- 0.44 ml/min/kg; volume of distribution, 1.59 +/- 0.51 liters/kg; and half-life, 7.2 +/- 1.5 h. For seven infants studied a second time, at a mean age of 17.7 days, an increase in the mean clearance (2.33 versus 4.35 ml/min/kg; P = 0.024) and a decrease in the half-life (7.3 versus 4.4 h; P = 0.003) were found. The ZDV clearance is low and the half-life is prolonged in premature neonates, but the clearance increases and the half-life decreases with postnatal age. Potentially toxic concentrations may accumulate in serum if the standard dosage for full-term infants is used. We suggest that initial ZDV dosing should be reduced to 1.5 mg every 12 h for preterm neonates.     

The trans-syn-I thymine dimer bends DNA by approximately 22 degrees and unwinds DNA by approximately 15 degrees

Chromium metabolism of lactating women was evaluated by measuring diet, breast milk, urine, and serum chromium in 17 subjects 60 d postpartum. Breast milk chromium concentration was similar for the 3 d of collection with a mean +/- SE concentration of 3.54 +/- 0.40 nmol/L (0.18 ng/mL). Dietary intake and urinary chromium values were also similar for each of the 3 collection days. Total chromium intake of lactating mothers (0.79 +/- 0.08 mumol/d) was greater than that of reference female subjects (0.48 +/- 0.02). There was a significant correlation (r = 0.84) between serum chromium and urinary chromium excretion. If a breast milk volume of 715 mL is assumed, chromium intake of exclusively breast-fed infants is < 2% of the estimated safe and adequate daily intake of 10 micrograms. In summary, breast milk chromium content is independent of dietary chromium intake and serum or urinary chromium values. Chromium intake also did not correlate with serum or urine chromium but there was a significant relationship between serum and urinary chromium concentrations.