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Biomedical subjects

I Rubenstein

Publications and source records attributed to I Rubenstein.

At least 19 recordsLinked to original sources
PubMed1998

Hyperbaric oxygen: a novel modality to ameliorate experimental colitis.

BACKGROUND: Hyperbaric oxygen (HBO) has been suggested to be beneficial in inflammatory bowel disease but the mechanisms responsible for its therapeutic effects have not been elucidated. AIM: To assess the effect of HBO treatment on colonic damage in two models of experimental colitis, and to examine whether this effect is mediated by modulation of NO synthesis. METHODS: Colitis was induced by either flushing the colon with 2 ml 5% acetic acid or intracolonic administration of 30 mg trinitrobenzenesulphonic acid (TNB) dissolved in 0.25 ml 50% ethanol. Rats were exposed to HBO (100% oxygen at 2.4 atmosphere absolute) for one hour twice on the day of colitis induction and once daily thereafter. Control rats were treated only with acetic acid or TNB. Rats were killed 24 hours after acetic acid administration or one and seven days after TNB treatment. The colon was isolated, washed, and weighed, the lesion area was measured, and mucosal scrapings were processed for determination of myeloperoxidase (MPO) and NO synthase (NOS) activities, prostaglandin E2 (PGE2) and leukotriene B4 (LTB4) generation. RESULTS: In control rats exposed for seven days to HBO, colonic NOS activity was significantly decreased by 61%, compared with its activity in untreated rats (2.93 (0.17) nmol/g/min). HBO significantly reduced by 51 and 62% the extent of injury induced by acetic acid and TNB respectively. The protection provided by HBO was accompanied by a significant decrease in colonic weight, PGE2 generation, MPO, and NOS activities. In acetic acid colitis, LTB4 generation was also significantly decreased. CONCLUSIONS: (1) HBO effectively decreases colitis induced by acetic acid and TNB. (2) The decreased NOS activity induced by HBO suggests that reduction in NO generation may be among the mechanisms responsible for the anti-inflammatory effect of HBO. (3) HBO may be considered in the treatment of patients with refractory inflammatory bowel disease.

Acetic Acid↗
PubMed1993

Transcriptional characterization of an alpha-zein gene cluster in maize.

A cluster of five alpha-zein subfamily 4 (alpha-zein SF4) genes are present in a 56 kb region of the maize W22 genome. Two types of alpha-zein SF4 genes are in the cluster. One of the genes, termed a type 1 (T1) alpha-zein SF4 gene, contains no early in-frame stop codons. Four of the genes, termed type 2 (T2) alpha-zein SF4 genes, contain one or two early in-frame stop codons. The base sequence of the T1 alpha-zein SF4 gene is similar (> 90%) to the sequences of any of the four T2 alpha-zein SF4 genes. However, their sequences differ markedly at distances greater than -875 bp upstream from the translation initiation codon of the alpha-zein coding region. This region of dissimilarity is well inside the functional 5'-flanking region for the genes since a 1.8 kb transcript is initiated in this region and the sequences of the T2 alpha-zein SF4 genes are similar in this region. Two sizes of mRNA transcripts, 1.8 kb and 0.9 kb, were detected in a gene specific manner for 4 of the 5 genes in this alpha-zein SF4 gene cluster. One of the T2 alpha-zein SF4 genes had only the 0.9 kb transcript. The RNA level for the 0.9 kb transcript of the T1 alpha-zein SF4 gene was 5- to 10-fold higher than the transcript levels of any of the T2 alpha-zein SF4 genes. In each case, the amount of the 0.9 kb transcript detected was at least 5-fold higher than the amount of the 1.8 kb transcript. A cDNA clone with a sequence identical to a T2 alpha-zein SF4 gene was isolated, providing the first direct evidence for the transcription of T2 alpha-zein genes containing early in-frame stop codon(s) in maize endosperm.

Base Sequence↗
PubMed1992

Genomic organization of an alpha-zein gene cluster in maize.

The genes encoding the alpha-zein proteins of maize constitute a large multigene family of some 75 genes. This multigene family can be divided into four subfamilies based on the nucleotide sequences of their genes and the deduced amino acid sequences of their proteins. We describe for the first time evidence of a clustering of five alpha-zein subfamily 4 (SF4) genes that are members of one of the major alpha-zein subfamilies in a 56 kb region of the genome of the maize inbred line W22. None of the other three known alpha-zein gene subfamilies (SF1, SF2, or SF3) are present in this cluster. The genomic region was reconstructed using restriction endonuclease maps to identify and align three overlapping cosmid clones isolated from a genomic library. The alpha-zein genes are not evenly spaced; the minimum distance between genes is 3.5 kb; the maximum is 13 kb. All the alpha-zein genes in the cluster have the same transcriptional orientation. The location and sequences of some of the repetitive DNA elements in this gene cluster were determined. We estimate that there are a minimum of eight repetitive DNA elements in this region. The sequences of the repetitive elements (not functionally defined) are located between or among the alpha-zein genes. The regions containing two of these repetitive elements (Rep1 and Rep4) have been sequenced; they are about 15 kb apart in the genome. These repetitive elements have similar sequences for about 300 bp out of the 400 bp compared. The regions of sequence similarity, however, are in reverse orientation to one another.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acid Sequence↗
PubMed1992

Molecular characterization of two types of 22 kilodalton alpha-zein genes in a gene cluster in maize.

Five genes of the alpha-zein subfamily four (SF4) are located in a 56 kb genomic region of the maize inbred line W22. Their nucleotide and deduced amino acid sequences have been determined. The sequences define two types of alpha-zein SF4 genes-type 1 (T1) and type 2 (T2). The single T1 alpha-zein SF4 gene codes for an alpha-zein protein with a M(r) of about 22,000. This is the first alpha-zein SF4 gene sequenced that contains no early in-frame stop codons in its coding sequence. The four T2 alpha-zein SF4 genes in this cluster contain one or two early in-frame stop codons. In addition, our T1 and T2 genes differ markedly in the base sequences of their distal 5' non-translated flanking regions. The nucleotide and the deduced amino acid sequences of these two types of alpha-zein SF4 genes are similar (greater than 90%) to one another and to all known alpha-zein SF4 genes and cDNAs. Of the known W22 alpha-zein SF4 genes, only one in six does not contain an early in-frame stop codon. If the number of alpha-zein SF4 genes is 15-20, then we estimate that only about 4 of the W22 alpha-zein SF4 genes are without in-frame early stop codons.

Amino Acid Sequence↗
PubMed1991

Characterization of the structure and transcription of an ubiquitin fusion gene from maize.

We have identified a maize ubiquitin (Ubi) fusion gene (UBF9) by screening a maize W22 genomic phage lambda library with a short (16-nucleotide) oligodeoxyribonucleotide probe derived from the sequence for the extension sequence of a yeast UB13 fusion gene. UBF9 consists of an UB monomer sequence (228 bp long) joined to an extension sequence (237 bp long). The extension sequence encodes a protein of 79 amino acids which shares extensive identity with similar extension aa sequences found in yeast, humans, barley and Arabidopsis thaliana. UBF9 encodes a small-size class of Ubi mRNAs in the maize tissues investigated. The UBF9 transcript is present in high levels in maize endosperm tissues 22 days after pollination. Genomic Southern blots of maize inbred W22 DNA indicate that the fusion gene sequences are present in multiple copies in the maize genome. Primer extension experiments indicate that the transcription start point is located at 80 bp upstream from the translation start codon of UBF9. Two 37-bp tandem repeated A + T-rich sequences are found in the 5'-flanking region of UBF9. The A + T-rich sequences share the motif, AATATTTTATT, which is present in a diverse set of plant genes.

Amino Acid Sequence↗
PubMed1991

Cigarette smoke extract attenuates endothelium-dependent arteriolar dilatation in vivo.

The purpose of this study was to examine the effects of cigarette smoke extract on endothelium-dependent and endothelium-independent dilatation of arterioles in vivo. Using intravital microscopy, we measured diameter of arterioles contained within the microcirculation of the hamster cheek pouch during suffusion with acetylcholine and nitroglycerin, before and after treatment with cigarette smoke extract. Under control conditions, acetylcholine and nitroglycerin produced dose-related dilatation of cheek pouch arterioles. Superfusion of cigarette smoke extract (1.0%) did not alter baseline diameter of arterioles or vasodilatation in response to nitroglycerin but impaired dilatation of arterioles in response to acetylcholine. Next, we examined the possibility that impaired dilatation of cheek pouch arterioles in response to acetylcholine after exposure to cigarette smoke extract may be related to the release of substances produced via the cyclooxygenase pathway. In indomethacin-pretreated hamsters, acetylcholine produced similar vasodilatation before and after exposure to cigarette smoke extract. Thus these findings suggest that cigarette smoke extract impairs endothelium-dependent responses of cheek pouch arterioles. The mechanism of impaired responses of cheek pouch arterioles after exposure to cigarette smoke extract appears to be related to the release of substances produced via the cyclooxygenase pathway.

Acetylcholine↗
PubMed1990

The evaluation of a cognitive behavioural treatment programme in outpatients with chronic pain.

This study is an attempt to investigate the efficacy of an outpatient cognitive behavioural group programme for the rehabilitation of patients with chronic pain. The programme, which took place over one afternoon per week for seven weeks and was conducted by a multidisciplinary team, aimed to increase patients' skills for coping with chronic pain and its social, emotional and physical consequences. Measures of pain intensity, mood, coping skills, physical disability and medication consumption were obtained on four separate occasions: twice pre-treatment, immediately post-treatment and at one month follow-up. Repeated measures analysis of variance showed significant improvements in mood, coping skills, physical disability and analgesic consumption despite less clear-cut improvement in ratings of pain intensity. These results parallel the findings of similar studies in the U.S.A. and their implications for the provision of services to chronic pain patients in the U.K. is discussed.

Adaptation, Psychological↗
PubMed1990

Effect of caffeine on ventilatory responses to hypercapnia, hypoxia, and exercise in humans.

The effect of oral caffeine on resting ventilation (VE), ventilatory responsiveness to progressive hyperoxic hypercapnia (HCVR), isocapnic hypoxia (HVR), and moderate exercise (EVR) below the anaerobic threshold (AT) was examined in seven healthy adults. Ventilatory responses were measured under three conditions: control (C) and after ingestion of either 650 mg caffeine (CF) or placebo (P) in a double-blind randomized manner. None of the physiological variables of interest differed significantly for C and P conditions (P greater than 0.05). Caffeine levels during HCVR, HVR, and EVR were 69.5 +/- 11.8, 67.8 +/- 10.8, and 67.8 +/- 10.9 (SD) mumol/l, respectively (P greater than 0.05). Metabolic rate at rest and during exercise was significantly elevated during CF compared with P. An increase in VE from 7.4 +/- 2.5 (P) to 10.5 +/- 2.1 l/min (CF) (P less than 0.05) was associated with a decrease in end-tidal PCO2 from 39.1 +/- 2.7 (P) to 35.1 +/- 1.3 Torr (CF) (P less than 0.05). Caffeine increased the HCVR, HVR, and EVR slopes (mean increase: 28 +/- 8, 135 +/- 28, 14 +/- 5%, respectively) compared with P; P less than 0.05 for each response. Increases in resting ventilation, HCVR, and HVR slopes were associated with increases in tidal volume (VT), whereas the increase in EVR slope was accompanied by increases in both VT and respiratory frequency. Our results indicate that caffeine increases VE and chemosensitivity to CO2 inhalation, hypoxia, and CO2 production during exercise below the AT.

Administration, Oral↗
PubMed1989

The organization and expression of a maize ribosomal protein gene family.

We have isolated several Zea mays cDNAs encoding the 40S subunit ribosomal protein S14. In maize, this ribosomal protein is encoded by a small multigene family, at least three members of which are expressed. S14 transcript levels are highest in mitotically active tissues, such as seedling shoot, developing endosperm, and tassel primordia, and lowest in tissues with little cell division, such as mature leaf and root. Very little S14 RNA is present in pollen, suggesting that translation of pollen mRNAs during pollen germination uses preformed ribosomes. During kernel development, the highest levels of S14 transcripts in endosperm tissue are found at 10-12 days postpollination; S14 RNA levels decline continuously from this point onward. The period of maximal expression of the S14 ribosomal protein gene appears to precede the onset of storage protein synthesis and does not correlate with the reported times of increased nucleolar volume or genome amplification.

Blotting, Northern↗
PubMed1986

The structure of the maize ribosomal DNA spacer region.

A combination of a single stranded plasmid vector and ordered deletions were used to determine the complete nucleotide sequence of a rDNA spacer region isolated from the DNA of maize Black Mexican Sweet suspension cells. The sequence reveals the presence of ten "200 base" subrepeats within the maize rDNA spacer region. By S1 protection experiments we have tentatively determined that the start of maize rRNA transcription is 144 bases 3' of the end of the last spacer subrepeat. We propose that the spacer subrepeats may have an important role in regulating maize rRNA transcription.

Base Sequence↗
PubMed1984

Transcription of a zein gene introduced into sunflower using a Ti plasmid vector.

A maize genomic clone containing a zein gene (Z4) was inserted into the T-region of the T37 Ti plasmid. Agrobacterium tumefaciens cells carrying this modified Ti plasmid were used to inoculate sunflower stemlets. Callus tissue active in nopaline synthesis was grown from a single transformed cell. DNA analysis of this tissue showed that the zein gene plus T-DNA was present in approximately 12 copies per diploid sunflower genome. A 1000 +/- 100 base RNA homologous to a zein probe could be isolated from the engineered sunflower tissue and the 5' end of this RNA was determined by S1 nuclease mapping. Two transcription start sites were detected. The positions of these transcription start sites and the ratio of the amounts of the two transcripts are identical for the Z4 gene in sunflower and in maize endosperm. Although the zein RNA isolated from the engineered sunflower tissue could be translated in a wheat germ system to yield an immuno-precipitable protein of the expected mol. wt., the presence of the zein protein in the sunflower tissue could not be demonstrated.

DNA, Recombinant↗
PubMed1984

Nucleotide sequence analysis of a zein genomic clone with a short open reading frame.

The nucleotide sequence of the zein genomic clone (W22)Z7 and its flanking sequences from the W22 inbred line of maize is reported. The sequence is 1587 bp long and contains 444 bp of 5' noncoding sequence and 342 bp of 3' noncoding sequence. The Z7 sequence belongs to a large complex multigene family and is a member of the B49 subfamily. It is 86% homologous to other known sequences from the same subfamily, but contains four in-frame termination codons caused by single base changes. Its flanking regions contain the usual eukaryotic transcriptional signals.

Base Sequence↗
PubMed1984

Cloning and sequencing of the ribosomal RNA genes in maize: the 17S region.

The maize genes for the 17S, 5.8S, and 26S ribosomal RNAs (rRNAs) are located on chromosome 6 and consist of 9-kb sequences repeated about 5,000-10,000 times per 2C. One of these sequences was isolated from a lambda library containing maize Eco RI genomic segments. The sequence of the small-subunit (17S) RNA was determined using the M13 shotgun-dideoxy sequencing approach. The maize sequence was compared with nuclear rRNAs from yeast, Xenopus, and rat. Using these sequences, it is possible to identify tentatively the start and the end points of the sequence of the maize nuclear small subunit rRNA. This RNA has a length of 1809 nucleotides. The alignment of all four sequences for maximal homology allows us to identify regions within the rRNA that have been conserved during eukaryotic evolution.

Animals↗
PubMed1984

Endosperm Protein Synthesis and l-[S]Methionine Incorporation in Maize Kernels Cultured In Vitro.

This study was conducted to examine protein synthesis and l-[(35)S] methionine incorporation into the endosperm of Zea mays L. kernels developing in vitro. Two-day-old kernels of the inbred line W64A were placed in culture on a defined medium containing 10 microCuries l-[(35)S] methionine per milliliter (13 milliCuries per millimole) and harvested at 10, 15, 20, 25, 30, 35, and 40 days after pollination. Cultured kernels attained a final endosperm mass of 120 milligrams compared to 175 milligrams for field-grown controls. Field and cultured kernels had similar concentrations (microgram per milligram endospern) for total protein, albumin plus globulin, zein, and glutelin fractions at most kernel ages.Sodium dodecyl sulfate-polyacrylamide gel electrophoresis and isoelectric focusing patterns for endosperm proteins were similar for field and cultured kernels throughout development. By 15 days, over 70% of the l-[(35)S]methionine taken up was present in endosperm proteins. Label incorporation visualized by fluorography generally followed the protein intensity of the stained gels. The high methionine content, low molecular weight zeins (i.e. 15 and 9 kilodaltons) were highly labeled. All of the radioactivity in hydrolyzed zein samples was recovered in the methionine peak indicating minimal conversion to l-[(35)S]cysteine. The procedure described here is suitable for long term culture and labeling experiments in which continued kernel development is required.

Journal Article↗
PubMed1982

Sequence analysis and comparison of cDNAs of the zein multigene family .

The nucleotide sequence of two zein cDNAs in hybrid plasmids A20 and B49 have been determined. The insert in A20 is 921 bp long including a 5' non-coding region of 60 nucleotides, preceded by what is believed to be an artifactual sequence of 41 nucleotides, and a 3' non-coding region of 87 nucleotides. The B49 insert is 467 bp long and includes approximately one-half the protein coding sequence as well as a 3' non-coding region of 97 nucleotides. These sequences have been compared with the previously published sequence of another zein clone, A30 . A20 and A30 , both encoding 19 000 mol. wt. zeins , have approximately 85% homology at the nucleotide level. The B49 sequence, corresponding to a 22 000 mol. wt. zein, has approximately 65% homology to either A20 or A30 . All three zeins share common features including nearly identical amino acid compositions. In addition, the tandem repeats of 20 amino acids first seen in A30 are also present in A20 and B49 .

Amino Acid Sequence↗
PubMed1982

Primary structure of a genomic zein sequence of maize.

The nucleotide sequence of a genomic clone (termed Z4 ) of the zein multigene family was compared to the nucleotide sequence of related cDNA clones of zein mRNAs. A tandem duplication of a 96-bp sequence is found in the genomic clone that is not present in the related cDNA clones. When the duplication is disregarded, the nucleotide sequence homology between Z4 and its related cDNAs was approximately 97%. The nucleotide sequence is also compared to other isolated cDNAs. No introns in the coding region of the zein gene are detected. The first nucleotide of a putative TATA box, TATAAATA , was located 88 nucleotides upstream of the first nucleotide of the first ATG codon which initiated the open reading frame. The first nucleotide of a putative CCAAT box, CAAAAT , appeared 45 nucleotides upstream of the first nucleotide of the zein cDNA clones in the 3' non-coding region also appeared in the genomic sequence at the same locations. The amino acid composition of the polypeptide specified by the Z4 nucleotide sequence is similar to the known composition of zein proteins.

Amino Acids↗
PubMed1981

The primary structure of a plant storage protein: zein.

The protein sequence of a representative of the zeins, the major storage proteins of maize, has been derived from the nucleotide sequence of a zein cDNA clone. This cDNA was sequence both by the Maxam and Gilbert and the M13-dideoxy techniques. The nucleotide sequence encompasses the non-translated 3' terminus of the mRNA, the entire coding sequence specifying both the mature zein protein and a small signal peptide, and a portion of the non-translated 5' region. The deduced amino acid composition and the amino-terminal amino acid sequence closely resemble those derived from chemical analysis of the zein protein fraction. The data presented represent the first complete amino acid sequence of a plant storage protein.

Amino Acid Sequence↗