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Biomedical subjects

A Dixit

Publications and source records attributed to A Dixit.

At least 37 records · Page 2Linked to original sources

Assessment of amplicons in the DNA from boiled tissue by PCR and AP-PCR amplification.

Polymerase chain reaction (PCR) is a technique sensitive enough to amplify small DNA fragments a billion-fold. The generation of amplicons either by PCR with a set of oligo primers or by arbitrarily primed AP-PCR with a single oligonucleotide primer is based on the availability of intact template and priming sites. With these approaches, it is possible to generate specific and random amplicons to assess the extent of damage to DNA caused by any of the physical, chemical, or environmental factors. We report the amplification of sex chromosome and autosome specific loci in the buffalo (Bubalus bubalis) genome by symmetrical and AP-PCR performed on DNA samples isolated from the muscle tissues that were boiled (treated) for different lengths of time. No difference was noticed in the amplification profile of DNA cooked for various lengths of time. However, after HinfI treatment, AP-PCR amplification of these DNAs revealed more bands on agarose gel than unrestricted samples. The successful amplification of the DNA samples isolated from the boiled tissues is attributed to the intactness of the amplicons. This suggests that despite storage for more than a year and subsequent heat treatment to the muscle tissues, the DNA remains a good substrate for PCR and AP-PCR amplification. Relevance of this work in the context of DNA probe technology is discussed.

Animals↗

Psychosocial development of urban children (below 2 years) using culture appropriate indicators of development.

Six hundred essentially normal children 15 days-2 years were randomly assessed for their nutritional and developmental status. Measurement of the mid-upper-arm circumference using the Jellife's technique was employed for a quick nutritional survey. For developmental assessment, the WHO suggested culture appropriate psychosocial Basic Test Battery was used. Shakir's classification of the results did not reveal any malnutrition. Analysis of the data revealed 'at par' performances in Gross Motor, Hearing and Self Help skills and delays in Vision and Fine Motor, Language and Concept Skills. Social skills were particularly advanced.

Child Development↗

Purification and characterization of ribulose-1,5-bisphosphate carboxylase from triticale.

Ribulose-1,5-bisphosphate carboxylase has been isolated from a synthetic cereal triticale and purified using a newly developed rapid procedure involving precipitation with ammonium sulphate (35-55% saturation), DEAE-cellulose (DE-52) chromatography and filtration through Sepharose CL-68. Molecular weights of the enzyme subunits are 15.5 and 52 kDa which corresponds to 540 kDa for the hexadecameric holoenzyme. Isoelectric focussing showed that the enzyme has a pI of 4.2. Various kinetic constants determined under aerobic conditions are: Km (CO2), 118 microM; Km (RuBP), 220 microM (at 20 mM NaHCO3) and Vmax, 690 nmole CO2 fixed/mg enzyme/min.

Cations↗

Inhibition of key enzymes of carbohydrate metabolism in regenerating mouse liver by ascorbic acid.

The effect of ascorbic acid on the key enzymes of carbohydrate metabolism e.g. hexokinases, phosphofructokinase, pyruvate kinase, lactate dehydrogenase, glucose-6-phosphate dehydrogenase and malic enzyme was determined in regenerating mouse liver. All the enzymes showed a significant increase in the activity during regeneration. Ascorbic acid reduced the activities of the enzymes in regenerating liver. A decrease in liver weight in ascorbic acid treated animals may be correlated with its effect on these enzymes as glycolytic pathway is the main source of energy required by the dividing cells.

Animals↗

Culture appropriate indicators for monitoring growth and development of urban and rural children below 6 years.

In this cross sectional study, 2000 apparently normal children aged 0-6 years (1200 urban and 800 rural), were nutritionally and developmentally assessed and their environment scrutinized for possible risk factors. Measurement of mid upper arm circumference (MUAC) using standard techniques revealed malnutrition in 44% of the rural and 24% of the urban children especially in the 2-6 years of age group. Culture appropriate indicators of psycho-social development picked up gross delays in gross motor (GM), vision and fine motor (V&FM) and language skills. Self help, concept hearing (SHCH) skills were recorded as normal while social skills were advanced particularly in the 0-2 years old urban group. By the use of the family protocols, low socio-economic status, malnutrition and 9 other risks factors have been generated for the urban group. No risk factor could be identified for the rural group. Better income emerged as the only real protective factor for the sample showing a direct positive relationship with the 45 skills tested, especially in the 2-6 years age group. Nineteen developmental skills were identified as powerful predictors of development. A prototype home based screening record was constructed for monitoring of growth and development which can be even used by minimally trained primary care worker.

Child↗

Effect of 17 beta-estradiol and ovariectomy on enzymes of carbohydrate metabolism in regenerating mouse liver.

Effect of exogenous 17 beta-estradiol and ovariectomy was determined on the activities of some enzymes of carbohydrate metabolism in regenerating mouse liver. 17 beta-estradiol increased liver weight and the activities of these enzymes when given after partial hepatectomy whereas ovariectomy, performed 2 weeks prior to hepatectomy, reduced the activities significantly. Estradiol administration to ovariectomized-partially hepatectomized animals restored the activities of glycolytic enzymes but not of G6P-DH and malic enzyme. This indicates that estradiol acts as a stimulator of growth of proliferating liver as it does in target tissue.

Animals↗

Interaction of human alpha fetoprotein with bilirubin.

Human alpha fetoprotein (AFP) binds bilirubin with an affinity somewhat lower than albumin. Free bilirubin was found to have an extinction maximum at 440 nm with an extinction coefficient of 4.97 x 10(4) M-1cm-1. AFP binding with the bile pigment elicits a blue shift while albumin interaction produced red spectral shift.

Bilirubin↗

Interaction of a positive regulatory factor(s) with a 106-base pair upstream region controls transcription of metallothionein-I gene in the liver.

The differential transcription of the cloned mouse metallothionein-I (MT-I) gene in tissues was studied in unfractionated and fractionated nuclear extracts from rat liver and brain. MT-I gene transcription was 10-fold greater in liver nuclear extract than in brain nuclear extract, whereas the level of transcription of the histone H4 gene was almost identical in both tissue extracts. 5' Deletion analysis of upstream sequences revealed that a 106-base pair (bp) region located between the -148- and -42-bp positions with respect to the transcription start site was responsible for the higher level of expression of the MT-I gene in the liver. Preincubation of the liver extract with the 106-bp fragment resulted in a significant decrease in MT-I gene transcription in the liver extract. In contrast, MT-I gene transcription in the brain nuclear extract was not altered by preincubation with the 106-bp upstream sequence. Mixing liver and brain extract did not diminish MT-I gene transcription normally occurring in liver nuclear extract. Preincubation of brain nuclear extract with the MT-I gene had no inhibitory effect on transcription of MT-I gene in liver nuclear extract. These studies suggest that neither an inhibitor nor a negative trans-acting factor in the brain is responsible for the differential transcription of MT-I gene; rather a positive regulatory factor(s) in the liver which interacts with the 106-bp upstream region contributes to the higher level of MT-I gene expression in this tissue.

Animals↗

A 37-base pair element in the far upstream spacer region can enhance transcription of rat rDNA in vitro and can bind to the core promoter-binding factor(s).

Previous studies in this laboratory have demonstrated that a 174-base pair (bp) rat rDNA spacer region located more than 2 kilobase pairs upstream of the initiation site, can enhance rat rDNA transcription in vitro independent of its orientation or distance or when inserted downstream of the initiation site. Further dissection of this region showed that transcription of a rDNA fragment containing just 37 bp of the spacer sequence, located between -2.183 and -2.219 kilobase pairs upstream of the initiation site, is 8-fold greater than that of the rDNA fragment devoid of the spacer element. Electrophoretic mobility shift assay demonstrated specific interaction of the 37-bp DNA fragment with a cellular protein(s). The spacer DNA competed for essential transcription factors as demonstrated by the absence of transcription following preincubation of the extract with the 37-bp fragment. Similar competition was also observed when a 58-bp PolI promoter was substituted for the enhancer fragment. The binding of the factor(s) to the enhancer element was not altered when coding and noncoding strands of the 37-bp oligodeoxynucleotide were used separately in the competition assay. Since the 37-bp enhancer region and the core promoter do not exhibit any significant sequence homology, the factor(s) appears to interact with these cis-acting elements in a sequence-independent manner.

Adenocarcinoma↗

A cis-acting sequence within the rat ribosomal DNA enhancer region can modulate RNA polymerase II-directed transcription of the metallothionein I gene in vitro.

Plasmids were constructed by inserting a 557-bp or 174-bp spacer fragment of rat ribosomal (r)DNA containing an enhancer element(s) at -148 bp upstream from a cloned mouse metallothionein gene (pMT-I). Transcription of these plasmids in a fractionated nuclear extract from a rat hepatoma resulted in 5 to 20-fold stimulation of MT-I gene transcription. This enhancement occurred independent of orientation of the enhancer or its distance from the metallothionein gene promoter or in the presence of the MT-I gene enhancer, and was sensitive to low levels of alpha-amanitin. Stimulation of MT-I gene transcription under the direction of the rDNA spacer element also occurred in HeLa nuclear extract, albeit to a smaller extent. Prior incubation of the nuclear extract with the 557-bp or 174-bp fragment resulted in as much as 5- to 10-fold stimulation of MT-I gene transcription. No significant effect on MT-I gene transcription was observed following preincubation with other DNAs. Preincubation of the extract with three subfragments of the 174-bp spacer inhibited MT-I gene transcription, which suggests that the majority of the 174-bp domain is required for binding to the negative regulatory factor(s) for MT-I gene transcription and that the subfragments can only interact with the positive core promoter-binding factor. The 37-bp subfragment, which has been shown to interact with a positive rDNA trans-acting factor, could also interact with a positive polymerase II (pol II) trans-acting factor. These studies have demonstrated that the 174-bp rat rDNA spacer element containing the pol I enhancer can also modulate pol II-directed transcription.

Animals↗

An enhancer element in the far upstream spacer region of rat ribosomal RNA gene.

To determine whether far upstream 5'-flanking sequences control rat rDNA transcription, we constructed plasmids containing several 5' and 3' deletions within the nontranscribed spacer region. In vitro transcription of these plasmids identified three enhancer regions, designated A, B, and C, which can dramatically stimulate transcription from the core promoter. Further analysis of region B showed that the enhancer element lies between -2.183 and -2.357 kilobase pairs upstream of the initiation site. The plasmid containing the 174-base pair enhancer element could stimulate rRNA gene transcription as much as 10-20-fold relative to transcription of the plasmid containing only the core promoter. This enhancer was not another promoter domain and could function irrespective of its orientation or distance from the promoter or when inserted downstream of the initiation site. Computer analysis of known sequences of enhancer regions A and C did not reveal any significant homology between these DNA segments and the 174-base pair enhancer element. Competition assay demonstrated that the enhancer element B forms a stable complex with the transcription factor(s) and that interaction between the enhancer and the factor(s) was essential for the stimulation of rDNA transcription. This is the first report of a mammalian ribosomal rDNA enhancer element that exhibits the characteristics of an RNA polymerase II enhancer.

Animals↗

Homologous ribosomal proteins in bacteria, yeast, and humans.

We describe sequences of two human ribosomal proteins, S14 and S17, and messenger RNAs that encode them. cDNAs were used as molecular hybridization probes to recognize complementary genes in rodent, Drosophila, and yeast chromosomal DNAs. Human ribosomal protein sequences are compared to analogous Chinese hamster, yeast, and bacterial genes. Our observations suggest that some ribosomal protein genes have been conserved stringently in the several phylogenetic lines examined. These genes apparently were established early in evolution and encode products that are fundamental to the translational apparatus. Other ribosomal protein genes examined, although similar enough to heterologous DNA sequences to indicate their structural relationships, appear to have diverged substantially during evolution, probably reflecting adaptations to different genetic environments.

Amino Acid Sequence↗

Primary structure of human ribosomal protein S14 and the gene that encodes it.

Chinese hamster ribosomal protein S14 cDNA was used to recognize homologous human cDNA and genomic clones. Human and Chinese hamster S14 protein sequences deduced from the cDNAs are identical. Two overlapping human genomic S14 DNA clones were isolated from a Charon 28 placental DNA library. A fragment of single-copy DNA derived from an intron region of one clone was mapped to the functional RPS14 locus on human chromosome 5q by using a panel of human X Chinese hamster hybrid cell DNAs. The human S14 gene consists of five exons and four introns spanning 5.9 kilobase pairs of DNA. Polyadenylated S14 transcripts purified from HeLa cell cytoplasma display heterogeneous 5' ends that map within noncoding RPS14 exon 1. This precludes assignment of a unique 5' boundary of RPS14 transcripts with respect to the cloned human genomic DNA. Apparently HeLa cells either initiate transcription at multiple sites within RPS14 exon 1, or capped 5' oligonucleotides are removed from most S14 mRNAs posttranscription. In contrast to the few murine ribosomal protein and several other mammalian housekeeping genes whose structures are known, human RPS14 contains a TATA sequence (TATACTT) upstream from exon 1. Three related short sequence motifs, also observed in murine and yeast ribosomal protein genes, occur in this region of the RPS14 gene. RPS14 introns 3 and 4 both contain Alu sequences. Interestingly, the Alu sequence in intron 3 is located slightly downstream from a chromosome 5 deletion breakpoint in one human X hamster hybrid clone analyzed.

Amino Acid Sequence↗

Spectrophotometric assay of the flavin-containing monooxygenase and changes in its activity in female mouse liver with nutritional and diurnal conditions.

A highly sensitive spectrophotometric assay was developed for measuring flavin-containing monooxygenase activity using methimazole (N-methyl-2-mercaptoimidazole) as the substrate. With the procedure described, flavin-containing monooxygenase activity can be accurately measured in whole cell homogenates without interference due to NADPH oxidase activities. The effects of detergents and octylamine on female mouse liver flavin-containing monooxygenase activity were characterized for whole homogenates and microsomes prepared under conditions which tend to cause or minimize microsomal aggregation. A small activation was observed with 0.2% (v/v) Emulgen 913 with nonaggregated microsomes; higher levels of detergents gave maximal activity with aggregated microsomes. Variations in the activity of the female mouse liver enzyme with nutritional state and time of day were evaluated. Higher specific activities were observed in homogenates and microsomes of livers from fed animals than from livers of 24-h starved animals, and higher specific activities were present in samples from livers of animals sacrificed in late afternoon than in the early morning. In the period where activity increased in fed animals (i.e., the AM to PM transition), a portion of flavin-containing monooxygenase was more resistant to thermal inactivation. Other properties are described which suggest structural differences for at least a portion of the flavin-containing monooxygenase. The possibility that these differences may be related to turnover of the flavin-containing monooxygenase is discussed.

Animals↗