Detection and characterization of a ring chromosome in the fission yeast Schizosaccharomyces pombe

NotI and SfiI genomic restriction maps were used to detect and characterize a ring chromosome II in a Schizosaccharomyces pombe strain with a meiotic defect on chromosome II. The ring chromosome was formed by an intrachromosomal fusion near, or at, the very ends of chromosome II.

Cloning of an ovine 11 beta-hydroxysteroid dehydrogenase complementary deoxyribonucleic acid: tissue and temporal distribution of its messenger ribonucleic acid during fetal and neonatal development

Glucocorticoids promote the development of many organ systems vital for extrauterine survival, and fetal cortisol provides the trigger for birth in sheep. The activity of glucocorticoids may be influenced at a cellular level by 11 beta-hydroxysteroid dehydrogenase (11 beta-HSD), which is responsible for the interconversion of cortisol and cortisone. To examine 11 beta-HSD gene expression during fetal development, two overlapping clones which yield a 1.4 kilobase (kb) complementary DNA encoding sheep 11 beta-HSD from a liver library were isolated by using a rat 11 beta-HSD cDNA as the probe. This cDNA contains a 879 base pair open reading frame for a protein of 292 amino acids that has more than 70% sequence identity to rat and human 11 beta-HSDs. To define the tissue distribution of 11 beta-HSD messenger RNA in sheep, selected tissues were collected from one fetus at day 130 and term (approximately 145 days), and from a nonpregnant ewe. Cellular RNA was extracted and subjected to Northern blot analysis, and a single 1.8 kb transcript was detected in the fetal and adult liver, lung, hypothalamus, anterior pituitary, and placenta. This was undetectable in adrenals and kidneys, but a smaller (1.5 kb) transcript was present in fetal and adult kidney RNA. The relative abundance of 11 beta-HSD mRNA was greatest in fetal and adult livers, and it was much higher in adult liver, lung, and kidney than in the corresponding fetal tissues. To examine whether 11 beta-HSD gene expression is developmentally regulated in the fetal sheep, liver, lung, and kidney tissues were taken from fetuses at day 60-70, day 100-110, day 125-130, at term, and from newborn lambs (24-48 h old). In the lung and kidney, the relative abundance of 11 beta-HSD mRNA did not change from day 60 to term but increased in the lungs of newborn lambs. In contrast, 11 beta-HSD mRNA levels in the liver increased between day 125 and term and rose further in the newborn. Collectively, these results demonstrate that 11 beta-HSD gene expression in sheep is regulated in a tissue-specific and developmentally programmed manner.

VDE endonuclease cleaves Saccharomyces cerevisiae genomic DNA at a single site: physical mapping of the VMA1 gene

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Immuno-PCR: very sensitive antigen detection by means of specific antibody-DNA conjugates

An antigen detection system, termed immuno-polymerase chain reaction (immuno-PCR), was developed in which a specific DNA molecule is used as the marker. A streptavidin-protein A chimera that possesses tight and specific binding affinity both for biotin and immunoglobulin G was used to attach a biotinylated DNA specifically to antigen-monoclonal antibody complexes that had been immobilized on microtiter plate wells. Then, a segment of the attached DNA was amplified by PCR. Analysis of the PCR products by agarose gel electrophoresis after staining with ethidium bromide allowed as few as 580 antigen molecules (9.6 x 10(-22) moles) to be readily and reproducibly detected. Direct comparison with enzyme-linked immunosorbent assay with the use of a chimera-alkaline phosphatase conjugate demonstrates that enhancement (approximately x 10(5)) in detection sensitivity was obtained with the use of immuno-PCR. Given the enormous amplification capability and specificity of PCR, this immuno-PCR technology has a sensitivity greater than any existing antigen detection system and, in principle, could be applied to the detection of single antigen molecules.

A Leu----His substitution at residue 93 in human corticosteroid binding globulin results in reduced affinity for cortisol

A steroid binding capacity assay and a radioimmunoassay were both used to measure corticosteroid binding globulin (CBG) in serum samples from 22 patients with sepsis. An approximately 50% discordancy between the two values in one patient suggested the presence of a CBG variant with reduced affinity for cortisol, and this was confirmed by Scatchard analysis. We therefore used the polymerase chain reaction to amplify exons that encode for human CBG from the genomic DNA of this patient. This revealed two mutations within the coding sequences: one of which results in a Leu----His substitution at residue 93 and another which encodes a Ser----Ala substitution at residue 224 of the human CBG polypeptide. To assess the impact of each substitution on the steroid binding affinity of CBG, each mutation was introduced separately into a normal human CBG cDNA, and the normal and mutated cDNAs were expressed in Chinese hamster ovary cells. Scatchard analysis of the CBG produced in culture indicated that the His93 mutation (Kd = 2.24 +/- 1.75 nM) reduced the cortisol binding affinity of CBG (mean +/- SD) significantly (P less than 0.024) when compared to normal CBG (Kd = 0.64 +/- 0.31 nM), while the Ala224 mutation (Kd = 0.63 +/- 0.33 nM) did not influence cortisol binding affinity. We therefore conclude that residue 93 may play an important role in determining the structure of the CBG steroid binding site.

Service increment for teaching and research (SIFTR): the Southampton experience

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Affinity capture electrophoresis for sequence-specific DNA purification

A new method, affinity capture electrophoresis (ACE), has been developed for the sequence-specific isolation of DNA. The target DNA is complexed with a biotinylated probe and electrophoresed in a gel equipped with a trap of immobilized streptavidin. This selectively captures the target molecule and its biotinylated probe, while other nontarget molecules pass through the trap. The target DNA is subsequently recovered from the trap by destroying the interaction between the target DNA and the biotinylated probe. Two variations of this technique, one using triple-helix formation and the other using hybridization with a uracil-containing DNA probe at the end of the target fragment, proved effective in model experiments. Since this technique requires no denaturation and handles DNA inside an agarose gel matrix, it is, in principle, applicable to the isolation of very large DNAs.

The Escherichia coli chromosome contains specific, unmethylated dam and dcm sites

The Escherichia coli chromosome encodes two methylases, dam and dcm, which recognize the sequences GATC and CC(A/T)GG, respectively. Specific dam and dcm sites on the E. coli chromosome were found to be unmethylated in vivo by using pulsed-filed gel electrophoresis experiments scanning megabase regions of DNA. Some sites were totally unmethylated. The dam sites display variable methylation depending on the local sequence, and, in general, their methylation shows complex modulation by growth conditions and growth rate, suggesting multiple protection mechanisms. Sites resistant to complete dam or dcm methylation appear to be distributed throughout the chromosome. These unusual sites may identify regions of the chromosome with interesting biological functions.

SwaI, a unique restriction endonuclease from Staphylococcus warneri, which recognizes 5'-ATTTAAAT-3'

A novel class-II restriction endonuclease designated SwaI was purified from Staphylococcus warneri. This enzyme cleaves adenovirus 2 DNA, SV40 DNA and M13mp7 at one site each, but does not cleave lambda, PhiX174, pBR322 or pBR328 DNA. SwaI recognizes the octanucleotide sequence 5'-ATTTAAAT-3', cleaving in the center of the recognition sequence creating blunt ended DNA fragments. SwaI was used to digest chromosomal DNA from various microorganisms and human cells.

A contiguous Not I restriction map of band q22.3 of human chromosome 21

A contiguous high-resolution NotI restriction map of the distal region of the long arm of human chromosome 21 was constructed by three strategies: linking clones to identify adjacent pieces of DNA, partial digestion to identify neighboring fragments, and cell line polymorphisms to prove identity or adjacency of DNA fragments. Twenty-nine single-copy DNA probes and five linking clone probes were used to determine the order of 30 Not I fragments, covering 10 megabases of DNA in band q22.3. Smaller Not I fragments occur preferentially in this region, suggesting that band q22.3 is unusually rich in genes, since Not I sites occur almost exclusively in CpG islands. Comparison of the physical map and genetic maps in this region reveals a 10-fold higher than average recombination frequency.

Hormonal regulation of corticosteroid-binding globulin biosynthesis in the male rat

Corticosteroid-binding globulin (CBG) is an acidic glycoprotein produced primarily by the liver and is the major glucocorticoid transport protein in rat blood. Various hormone treatments are known to modify plasma CBG levels and may thereby influence the bioavailability of glucocorticoids. We have, therefore, examined serum CBG and hepatic CBG mRNA levels in male rats after sc steroid (25 micrograms/100 g BW twice daily of dexamethasone, prednisolone, corticosterone, estrone, estradiol, ethinyl estradiol, progesterone, or 5 alpha-dihydrotestosterone) or T4 (10 micrograms/100 g BW twice daily) administration. After dexamethasone treatment, serum CBG levels decreased significantly (P less than 0.002) within 48 h and were 26% of those in vehicle-treated animals by 72 h. At this time, CBG mRNA was undetectable in liver RNA extracts by Northern blotting or solution hybridization, and nuclear run-off experiments indicated that dexamethasone reduces CBG gene transcription in the liver by at least 14-fold. Treatment with ethinyl estradiol also reduced serum CBG levels significantly (P less than 0.015) compared to pretreatment values. No other significant changes in serum CBG levels were observed after any other steroid hormone treatment, and alterations in hepatic CBG mRNA levels were only observed after dexamethasone treatment. T4 administration for 72 h increased serum CBG and hepatic CBG mRNA levels by 66% and 39%, respectively, but did not influence the rate of CBG gene transcription. Thus, increased CBG biosynthesis after thyroid hormone treatment appears to be due to an increase in CBG mRNA stability. No change in the Concanavalin-A-binding properties of CBG molecules was observed after treatment with either dexamethasone or T4, and this suggests that these hormones do not influence the type of oligosaccharide chains associated with this protein. We, therefore, conclude that dexamethasone and T4 regulate hepatic CBG biosynthesis in the rat by modulating CBG mRNA synthesis and stability, respectively.

Multiple cystine stone formations on an indwelling ureteral stent treated by extracorporeal shock wave lithotripsy

Multiple large cystine stones formed on an indwelling ureteral stent used in the medical management of a 12-year-old boy with obstructing renal stones and cystinuria. Extracorporeal shock wave lithotripsy fragmented the cystine stones and allowed for extraction of the stent by cystoscopy.

Is there a role for fluconazole in the treatment of vulvovaginal candidiasis?

OBJECTIVE

To review the data describing the use of fluconazole in the treatment of vulvovaginal candidiasis (VVC).

DATA IDENTIFICATION

A MEDLINE search of the English-language literature and a bibliographic review of pertinent articles examining the use of fluconazole in the treatment of VVC.

STUDY SELECTION AND DATA EXTRACTION

Relevant open and controlled studies reporting on the efficacy, associated adverse effects, or both of fluconazole for the treatment of VVC are reviewed. Appropriate conclusions and/or data are extracted from each article and described.

DATA SYNTHESIS

Studies comparing fluconazole with ketoconazole and topical antifungal agents such as clotrimazole and miconazole have shown fluconazole to be equally efficacious with minimal adverse effects. Most of these trials used single-dose fluconazole, which would theoretically lead to a high degree of medication compliance. Fluconazole also has shown promise at diminishing VVC relapse or recurrence, possibly because of more complete vaginal and rectal eradication of Candida species. Pharmacoeconomically, single-dose fluconazole therapy is cost-effective; however, the recent approval of miconazole and clotrimazole by the Food and Drug Administration for over-the-counter use may limit this potential advantage.

CONCLUSIONS

Until additional data are available, fluconazole may be considered a treatment alternative for women with VVC who experience frequent relapses or recurrences, or for those who are noncompliant with standard therapy.

The effect of DNA concentration on mobility in pulsed field gel electrophoresis

The effect of DNA concentration on pulsed field gel electrophoretic mobility was studied for human genomic DNA prepared in agarose inserts at 8-800 micrograms/ml and digested to completion with Not I. An eighth of each 100 microliter insert was used to produce DNA loads of 0.1 to 10 micrograms per lane. The mobility of single copy restriction fragments, as detected by hybridization, was largely concentration independent when DNA concentrations were 80 micrograms/ml or less. However, at DNA concentrations of 200 micrograms/ml and greater, dramatic effects of DNA concentration are evident. In the worst case, at 800 micrograms/ml, the apparent size of a DNA fragment is almost 2.5 times its true size. At constant DNA concentrations, increasing the DNA mass loads by loading larger insert slices had no further effect on DNA electrophoretic mobility, although the bands were broader for bigger insert slices. Thus, for precise and accurate sizing in pulsed field gel electrophoresis the DNA concentration in agarose inserts should not be greater than 80 micrograms/ml (10(7) diploid human cells/ml agarose insert).

Long-distance restriction mapping of the proximal long arm of human chromosome 21 with Not I linking clones

Human chromosome 21 is the smallest of the 22 autosomes and 2 sex chromosomes. Hybridization of the human repetitive sequence Alu to pulsed-field gel-fractionated Not I-digested genomic DNA from a human-mouse hybrid cell line containing chromosome 21 as the sole human component identified chromosome 21 Not I restriction fragments. A Not I restriction map of regions of the chromosome was constructed, by identifying neighboring Alu bands with Not I linking clones. This approach simplifies the task of physical mapping and avoids ambiguities in Not I fragment assignments that arise from gel-to-gel mobility variations. A contiguous map was constructed with six Not I linking clones that covers at least the proximal one-third of the long arm of chromosome 21 and spans 20 megabases. A more detailed restriction map revealed 11 likely CpG islands in this region and localized 11 additional DNA markers.

Caldesmon content of mammalian smooth muscles

In the present study we have used a quantitative immunoblotting method to measure the caldesmon content of a variety of smooth muscles with distinctly different contractile phenotypes. Two tonic vascular smooth muscles and several phasic smooth muscles were examined. The caldesmon, actin and myosin contents of each muscle type were measured. Smooth muscle from large arteries (i.e. bovine aorta and porcine carotid artery) had the lowest caldesmon content and phasic muscles (e.g. rat uterus and guinea pig taenia coli) had the highest. The molar ratio of monomeric caldesmon to monomeric actin was 1:205 for the aorta and carotid artery versus 1:22-28 for the taenia coli and uterus. The molar ratio of caldesmon to monomeric myosin heavy chain was 1:9 for the aorta and carotid versus 1:2 for the uterus and taenia coli. The caldesmon contents of canine trachealis and rabbit ileum were intermediate between these extremes. Evidence was found for the presence of both tissue- and species-specific caldesmon isoforms. The relatively high caldesmon content in rat uterus and guinea pig taenia coli suggests the possibility that the contractile phenotype associated with phasic smooth muscles may be dependent on the presence of caldesmon.

Distribution of interspersed repeats (Alu and Kpn) on NotI restriction fragments of human chromosome 21

Interspersed repeated sequences (Alu and Kpn) were used as probes to detect a set of Not I restriction fragments of human chromosome 21 from the hybrid cell line WAV17. Forty different Not I fragments, ranging in size from less than 0.05 megabase (Mb) to 7.0 Mb, were identified. The total length of these fragments was 47.3 Mb. This length provides an estimate of the minimum size of the chromosome and a minimum number of fragments to be ordered to create a complete restriction map. The average length Not I fragment is 1.2 Mb. Alu and Kpn fragments are not always coincident: a 2.9-Mb fragment is detected with Kpn but not with Alu, and 13 fragments, ranging from less than 0.05 Mb to 5.6 Mb, are detected with Alu but not with Kpn; the 26 remaining fragments, covering 75% (35.3 Mb) of the total length, are detected with both repetitive probes. The presence of so many noncoincident fragments and the high variation of the hybridization signal intensities of the fragments suggest a very nonuniform distribution of Kpn and Alu repeats.

Hypothyroidism producing reversible dementia. A challenge for medical rehabilitation

The evaluation of dementia for reversible causes should not be overlooked. Hypothyroidism is a reversible cause for dementia. Mental status is one of the important factors to be assessed prospectively to determine whether a patient is likely to benefit from intensive inpatient rehabilitation. Because of the negative effect of dementia on the learning process during intensive inpatient medical rehabilitation, it alone may be a sufficient reason to consider alternatives to intensive inpatient rehabilitation. On our rehabilitation unit, hypothyroidism causing confusion was recognized and corrected in two patients. The thyroid-stimulating hormone test is suggested as a screening tool.

Residues 20, 22, and 26 determine the subtype specificities of staphylococcal enterotoxins C1 and C2

Nonconserved residues of staphylococcal enterotoxin C1 (SEC1) were converted to their counterparts in SEC2. The mutants that resulted were examined for reactivity with monoclonal antibodies (MAbs). Substitution at position 20, 22, or 26 interfered with binding of an SEC1-specific MAb. SEC1 mutants with substitutions at all three positions reacted only with an SEC2-specific MAb. Antibody-binding patterns were not associated with isoelectric point differences. All mutants retained biological activity.

Sequence-specific DNA purification by triplex affinity capture

A DNA isolation procedure was developed by using triple-helix formation and magnetic separation. In this procedure, target DNA is captured by a biotinylated oligonucleotide via intermolecular triplex formation, bound to streptavidin-coated magnetic beads, and recovered in double-stranded form by elution with a mild alkaline buffer that destabilizes the triple helix. The effectiveness of the procedure was demonstrated by a model experiment with an artificially reconstructed library and, also, by the isolation of (dT-dC)n.(dG-dA)n dinucleotide repeats from a human genomic library. This procedure provides a prototype for other triplex-mediated DNA isolation technologies.

Estimation of the mean effective organ doses for total body irradiation from Rando phantom measurements

For the total body irradiation (TBI) procedure, it is necessary to compare the mean dose obtained from the tissue or organs and the estimated dose equivalent value from the computer program. Due to the easy-access of the Rando phantom and repeatability of TLDs and its output, the results from the experiment are quite encouraging for the verification of the dose distributions from total body irradiation at the given prescribed monitor units. The estimation of effective dose equivalent particularly across the lung sections was studied by combinations of using arms as the scatter volume to compensate for the inhomogeneity across the breast portion, as well as using the spoiler for skin-sparing purposes. The results were based upon various beam quality such as 4 MV, 6 MV, and 10 MV X rays. One series of experiments performed for this survey to ascertain the dose equivalent of the tissues was conducted. This paper describes the method and procedure for comparison between the measured data and computed data as a reference in the dosimetry of total body irradiation. Comparison of the measured and computed data for the largest collimated field shows that the calculated dose rates do not differ by more than 2% from the measured data. Because uncertainty is inherent in non-patient-like phantoms, the calculated data may be served as a reference for the dosimetry. For the total body irradiation setup, considering the radiation field size and treatment distances commonly employed, we conclude that the best combination of the patient setup will be (1) laying both arms down as compensation for lung inhomogeneity, and (2) the spoiler, which is made of acrylic about 8 mm thick and functions like a bolus, is needed to reduce the skin sparing effects and contribute the uniform dose distribution. The beam spoiler with the frame stands near the patient during the treatment.

Determination of ligand-binding specificity by alternative splicing: two distinct growth factor receptors encoded by a single gene

Expression cDNA cloning and structural analysis of the human keratinocyte growth factor receptor (KGFR) revealed identity with one of the fibroblast growth factor (FGF) receptors encoded by the bek gene (FGFR-2), except for a divergent stretch of 49 amino acids in their extracellular domains. Binding assays demonstrated that the KGFR was a high-affinity receptor for both KGF and acidic FGF, while FGFR-2 showed high affinity for basic and acidic FGF but no detectable binding by KGF. Genomic analysis of the bek gene revealed two alternative exons responsible for the region of divergence between the two receptors. The KGFR transcript was specific to epithelial cells, and it appeared to be differentially regulated with respect to the alternative FGFR-2 transcript. Thus, two growth factor receptors with different ligand-binding specificities and expression patterns are encoded by alternative transcripts of the same gene.