Malignant mesothelioma of the tunica vaginalis testis.
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Aged↗
Biomedical subjects
N Hasan
Publications and source records attributed to N Hasan.
Intralobar bronchopulmonary sequestration: antenatal diagnosis.
A child with the antenatal diagnosis of pulmonary cystic adenomatoid malformation underwent thoracotomy and an intralobar bronchopulmonary sequestration was found. Histological examination of the resected specimen showed cystic adenomatoid malformation within the sequestered segment.
Child, Preschool↗
Signet ring cell differentiation in adenocarcinoma of the prostate: a study of five cases.
Signet ring cell differentiation in adenocarcinoma of the prostate is uncommon. In a review of 200 cases of prostatic carcinoma, we identified five cases with this change, all in moderately to poorly differentiated prostatic carcinomas. The signet ring cells in prostatic carcinoma contain an intracytoplasmic lumen, shown on electronmicroscopy to be lined by microvilli. Transition stages were seen from solid to acinar to signet ring cells to mucinous variants. We believe that this change is part of the spectrum of appearances of prostatic carcinoma and should not be regarded as a subtype of specific significance.
Adenocarcinoma↗
Tuberculosis of striated muscle.
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Bacteremia↗
Integration host factor (IHF) binds to many sites in the A + T-rich b2 region of phage lambda DNA.
Computer analysis of almost the entire b2 region of lambda phage (nt 22346-27475) revealed 23 consensus-like ihf sites, with eleven pointing in one direction and twelve in the opposite direction [27 bp; Kur et al., Gene 81 (1989) 1-15]. To confirm the significance of this finding experimentally, the region was subdivided into 21 fragments and examined for integration host factor (IHF) binding by gel retardation and a variety of footprinting methods. Out of 21 fragments examined 13 were found to be retarded on gels in the presence of IHF and to contain one to three ihf sites each. All sites which differ by up to 2 bp from our 27-bp consensus ihf sequence can bind IHF in vitro. However, three of the computer-predicted sites overlap with sites of opposite orientation; therefore we could not determine at the present time which of the two antiparallel sequences binds IHF. We have compared the predictive values of various kinds of consensus sequences and show that our 27-bp consensus ihf sequence agrees best with the experimental data. It was demonstrated by Kur et al. [Virology 168 (1989) 236-244] that the IHF protein represses transcription from promoters located close to the right terminus of the b2 region, within the phage lambda attachment site. We discuss the possibility that some of the IHF-binding sites could be instrumental in repressing in vivo transcription from the A + T-rich b2 region during the lambda prophage state [Rosenvold et al., Virology 107 (1980) 476-487].
Amino Acid Sequence↗
Retroperitoneal jejunal diverticulum: cause of intestinal obstruction.
A 3-week-old boy presented with repeated episodes of vomiting and constipation. At laparotomy a jejunal diverticulum arising from its antimesenteric border and extending retroperitoneally was found. The narrow neck of diverticulum caused a situation similar to a Richter's hernia. The fundus of diverticulum was attached to the upper pole of left kidney. A retroperitoneal jejunal diverticulum is a new addition to the cause of neonatal intestinal obstruction.
Diverticulum↗
Dose-dependent vitamin D3, 25-hydroxyvitamin D3 and 1,25-dihydroxyvitamin D3-induced hypercalcemia and hyperphosphatemia, and the correlative changes in the activity of ultimobranchial and parathyroid glands of the toad, Bufo andersoni Boulenger.
Vitamin D3, 25(OH) vitamin D3 and 1,25 (OH)2D3 were administered daily to unfed male Bufo andersoni for 15 days which resulted in a significant hypercalcemia and hyperphosphatemia in a dose-dependent fashion. 1,25(OH)2D3 is more potent than the other metabolites. The treatment activated ultimobranchial gland but induced degenerative changes in parathyroid of the toads.
Animals↗
Class-IIS restriction enzymes--a review.
Class-IIS restriction enzymes (ENases-IIS) interact with two discrete sites on double-stranded DNA: the recognition site, which is 4-7 bp long, and the cleavage site, usually 1-20 bp away from the recognition site. The recognition sequences of ENases-IIS are totally (or partially) asymmetric and all of the characterized ENases-IIS are monomeric. A total of 35 ENases-IIS are described (80, if all isoschizomers are taken into consideration) together with ten related ENases (class IIT), and 15 cognate methyltransferases (MTases-IIS). The physical, chemical, and molecular properties of the ENases-IIS and MTases-IIS are reviewed and many unique applications of this class of enzymes are described, including: precise trimming of DNA; retrieval of cloned fragments; gene assembly; use as a universal restriction enzyme; cleavage of single-stranded DNA; detection of point mutations; tandem amplification; printing-amplification reaction; and localization of methylated bases.
Base Sequence↗
Calcium pyrophosphate dihydrate deposition disease: morphological and microanalytical features.
The light microscopic and polarization appearances of calcium pyrophosphate dihydrate crystal deposits in tissues are reviewed. In routine sections haematoxylinophilic crystalline deposits with a feathery or brush-like pattern are typical of calcium pyrophosphate dihydrate. Short rhomboidal crystals showing positive birefringence are seen on polarization; X-ray microanalytical and infrared spectroscopic data support the specificity of these appearances. The appearances of the crystal deposits in decalcified specimens are also described. We include six cases of calcium pyrophosphate dihydrate deposition within periarticular bone; to the best of our knowledge this has not previously been described.
Aged↗
Alterations in the p'R promoter of coliphage lambda modify both its activity and interaction with the integration host factor (IHF).
A limited number of deletion/insertions and a point mutation in the -35 region of the p'R promoter of phage lambda were examined and found to influence both transcription and its repression by the integration host factor (IHF). Positive effects on transcription (in the absence of IHF) are small (up to 1.4-fold) and are caused by a deletion-substitution upstream of the -35/ihf site. Up to three base changes in the -35 promoter element seem to be tolerated, with only a small negative effect on transcription. In some cases, effective transcription requires supercoiling of such mutant template. Since an ihf sequence overlaps the -35 region of p'R, IHF represses transcription. Repression is correlated with IHF binding and consequent DNA bending, as assessed by gel retardation experiments. Nine p'R mutants were tested for their IHF binding and repression; the results confirm the consensus sequence, 5'-W2WWWWN7WWWWCARNWN2TTR derived from the hydroxyl radical footprinting, where the bold letters indicate the IHF-protected bases and W is A or T, R is A or G and N represents A, T, G or C. Perhaps surprisingly, some mutations just upstream or downstream of this ihf sequence also affect IHF binding, as observed not only for the pR'/ihf but also for the att H' site of lambda. Supercoiling in some cases permits the IHF-mediated repression to be overcome, probably by increasing the RNA polymerase binding and/or decreasing the interaction with IHF. All our data are consistent with a model which assumes that IHF initially binds to one or two ihf contact points depending on preexisting DNA topology, bends DNA, and completes the remaining contacts while finally adjusting the DNA conformation to establish the best fit within the minor groove of the double helix. Effective IHF repression of transcription would thus depend on several factors, including: (1) the sequence, and (2) the initial conformation of the ihf site, together with (3) the capacity of IHF to compete with RNA polymerase for the overlapping binding sites.
Bacterial Proteins↗
The role of the direct repeat in qut-controlled antitermination in phage lambda.
For antitermination of transcription from the late p'R promoter of phage lambda, a cis-acting qut sequence, which overlaps with p'R, is required, together with the product of lambda gene Q. Using our BspMI-mediated multicycle technique for generation of precise deletions, we have confirmed that deletions removing DNA downstream of +18 bp (counted from the p'R-controlled transcriptional start point s'R = +1) do not affect the efficiency of qut antitermination; at the same time we found that deleting one more bp (shifting the right-hand boundary to bp +17) reduces antitermination by only 20%. Deleting another 5 or 6 bp (+11 or +12 bp right-hand qut boundary), decreases antitermination by about 80%. These deletions reduce the 9/10-bp-direct repeat (5'-TGGGT(A or T)AATT)2 in qut to only the five italicized bp. Similar strong reduction in antitermination (by about 68%) was obtained with +16 bp qut boundaries, in constructs which also contained 2- or 3-bp insertions between bp +11 and +12 or between +12 and +13. Since the latter deletions retain only 5/10 bp of the direct repeat, it appears that antitermination is dependent on the length and intactness of the direct repeat.
Bacteriophage lambda↗
An MboII/FokI trimming plasmid allowing consecutive cycles of precise 1- to 12-base-pair deletions in cloned DNA.
A novel trimming plasmid has been designed which allows, in a preprogrammed fashion, the precise deletion of up to 12 bp per cleavage cycle, from one end of a cloned fragment. The plasmid, which carries the dhfr gene, contains unique recognition sites for two class-IIS restriction enzymes, MboII and FokI, which are arranged in the form of a cassette, so that consecutive cleavages with these endonucleases, followed by blunting with mung bean nuclease (MB), will precisely delete 12 bp of adjacent cloned DNA. When either MboII or FokI is used alone (followed by MB), 1 or 4 bp are removed, respectively. The final step in the trimming cycle is religation of the plasmid with T4 ligase. After required number of cycles, plasmids were transformed into Escherichia coli C600, and transformants selected by resistance to trimethoprim. Since the MboII/FokI cassette remains intact during these operations, one can repeat the cycle, consisting of cleaving, MB blunting and religation, several times, each time removing up to 12 bp from the cloned target DNA. Examples are provided of one-, two- and three-cycle trimmings.
Base Sequence↗
Physical and biological consequences of interactions between integration host factor (IHF) and coliphage lambda late p'R promoter and its mutants.
The integration host factor (IHF) binds to a site (ihf) that overlaps the -35 region of the phage lambda late rightward promoter (p'R). This interaction represses p'R-promoted transcription, both in vivo and in vitro. In vivo repression was observed when a plasmid carrying both p'R and the galK reporter gene was transfected into IHF+ or IHF- hosts. In vitro repression of transcription by IHF was observed only with linear, but not with supercoiled wild-type p'R templates. When binding to ihf, IHF imposes a strong bend on the DNA and protects this site from cleavage by neocarzinostatin, pancreatic DNase I, and hydroxyl radicals, as assessed by footprinting experiments. Both the functional and nonfunctional p'R mutants, in which the upstream part of the -35 region was replaced by an EcoRI linker, show modified behavior toward IHF. Some are more sensitive to IHF-mediated repression, even in the supercoiled form, while others have lost their affinity for IHF. We conclude that IHF binding depends not only on the consensus ihf sequence, but also on a suitable combination of the sequences of both ihf and neighboring regions, together with the DNA conformation, which includes both natural and imposed bends in DNA and the degree of supercoiling. Based on most of the present data, it is difficult to predict the relationship between the ihf sequence and IHF interaction, since two very different sequences (less than 50% homology) show strong IHF binding, whereas very similar sequences (80-87% homology) show a very different behavior. However, the hydroxylradical footprinting data show that three A + T-rich sequences are protected by IHF: the central sequence, which overlaps the -35 region of p'R, and two flanking sequences removed by one helix turn. All three sequences are located on the same face of the helix, and the amino acid side chains of IHF seem to occupy the narrow minor groove. A novel consensus sequence is proposed.
Bacterial Proteins↗
Repression of transcription from the b2-att region of coliphage lambda by integration host factor.
The central b2-att region of coliphage lambda is known to be transcriptionally active in vitro, but silent in vivo in lambda lysogens. To explain such in vivo repression of transcription originating in the b2-att region, we explored the effect of the Escherichia coli integration host factor (IHF), the product of E. coli genes himA and himD, especially since the att region contains several IHF-binding sites. Using various lambda DNA templates, we mapped the transcripts which are initiated in vitro in the attP region by the RNA polymerase and found that there are three rightward (RI, RII, and RIII) and one leftward (LI) transcripts. All four of them are repressed by a factor of about 10 by 10 micrograms IHF/ml. Moreover, in in vivo experiments we found that plasmids carrying the attP fragment cannot be established and maintained in IHF-hosts. These results indicate that IHF may play a significant auxiliary role in repressing transcription in the prophage state.
Attachment Sites, Microbiological↗
Benzodiazepine use and abuse by patients at outpatient clinics.
The charts of 2,719 patients from several outpatient clinics were reviewed for evidence of use and abuse of benzodiazepines. According to the chart data and interviews with physicians, no patient met the criteria for benzodiazepine abuse or dependence.
Aged↗
Antisense RNA does not significantly affect expression of the galK gene of Escherichia coli or the N gene of coliphage lambda.
The effect of antisense RNA on the expression of genes galK and N was studied in vivo. These two genes were either present in the Escherichia coli chromosome, as single copies, or were cloned on plasmid vectors. Antisense RNA was supplied from multicopy vectors where the entire galK or N gene, or only their N-proximal portions, were cloned in the antisense orientation downstream from the strong PL, PR or lacZp promoters. In all of the experiments there was no significant inhibition of the galK or N expression by up to a 50-fold excess of the specific antisense RNAs, for both the in cis and in trans experimental designs. The excess of the antisense RNA was calculated as based on respective copy numbers, but was not experimentally measured. The apparent five-fold regulatory effect observed in one of the experiments was found to be artifactually caused by unexpected creation of a terminator in one of our constructs. To avoid such artifacts, all our constructs were equipped with the nut-N antitermination system. We conclude that the reported antimessenger-mediated inhibition of gene expression is not a general phenomenon, but must require some special features which are not present in the galK and N systems.
Bacteriophage lambda↗
Control of cloned gene expression by promoter inversion in vivo: construction of improved vectors with a multiple cloning site and the Ptac promoter.
We have constructed three gene-expression plasmids which contain (an) invertible promoter(s) and a multiple cloning site. We used either the plac promoter or the ptac-plac tandem promoters, the latter directing a more than fourfold increase in expression of the galK reporter gene in Escherichia coli host. All these plasmids were derived from the pNH7a expression plasmid of Podhajska et al. [Gene 40 (1985) 163-168]. Like pNH7a, these vectors have three novel properties: (i) in the 'OFF phase', the promoter is facing away from the gene to be expressed, (ii) the 'ON phase' is attained by the rapid and efficient inversion of the promoter mediated by the phage lambda Int product and the flanking attP and attB sites, which have a divergent orientation, and (iii) only a short heat pulse is required for the efficient inversion of the promoter and switching from the OFF to the ON phase. As for the pNH7 a vector, the present plasmids contain the nut-N transcriptional antitermination system, which permits efficient gene expression even if terminator(s) happen to be present between the promoter(s) and the expressed gene. The promoter inversion is rapid and over 95% efficient, as assayed by restriction analysis and galactokinase assay. Many genes could be conveniently cloned in the multiple cloning site, and then either kept totally silent or expressed in a rigidly controlled manner. Moreover, the pNH8, pNH16 and pNH18 plasmids, with already inverted promoters, could be used for expression of cloned genes, either in an unregulated manner or regulated by the lac repressor. They would be particularly useful for genes associated with terminators affecting their expression.
Attachment Sites, Microbiological↗