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Biomedical subjects

R Daniel

Publications and source records attributed to R Daniel.

At least 55 records · Page 3Linked to original sources
PubMed1996

Cloning, sequencing, and overexpression of the genes encoding coenzyme B12-dependent glycerol dehydratase of Citrobacter freundii.

The genes encoding coenzyme B12-dependent glycerol dehydratase of Citrobacter freundii were cloned and overexpressed in Escherichia coli. The B12-free enzyme was purified to homogeneity. It consists of three types of subunits whose N-terminal sequences are in accordance with those deduced from the open reading frames dhaB, dhaC, and dhaE, coding for subunits of 60,433 (alpha), 21,487 (beta), and 16,121 (gamma) Da, respectively. The enzyme complex has the composition alpha2beta2gamma2. Amino acid alignments with the subunits of the recently sequenced diol dehydratase of Klebsiella oxytoca (T. Tobimatsu, T. Hara, M. Sakaguchi, Y. Kishimoto, Y. Wada, M. Isoda, T. Sakai, and T. Toraya, J. Biol. Chem. 270:7142-7148, 1995) revealed identities between 51.8 and 70.9%.

Bacterial Proteins↗
PubMed1996

The ABL genes in normal and abnormal cell development.

Genetic alteration of the c-abl protooncogene has led to abnormal cellular development, primarily within the hemopoietic system. Different forms of oncogenic alteration have variations in biological strength for cellular transformation. The abnormal Abl oncoproteins are known to suppress apoptosis, which may be the basis for causing leukemia development. However, recent evidence also shows that c-abl proto-oncoprotein can inhibit apoptosis. Expression of the Abl oncoprotein in hemopoietic stem cells (HSCs) also results in alteration in the expression of certain cell surface molecules such that the interaction between HSCs and their marrow stroma microenvironment has become abnormal. The basis for the genetic alteration of the c-abl protooncogene in patients with chronic myelogenous leukemia may or may not be due to genetic imprinting.

Animals↗
PubMed1996

Isoform-specific functions of c-abl: type I is necessary for differentiation, and type IV is inhibitory to apoptosis.

The c-abl proto-oncogene is expressed ubiquitously during development. There are two predominant isoforms, type I and type IV. Their biological functions in cell growth and development are unknown. To examine their respective biological roles, we transduced 70Z/3 lymphoid cells with antisense sequences specific to each respective isotype. When the cells were incubated with antisense oligonucleotides against type IV c-abl but not against type I c-abl, induction of apoptosis was observed, as measured by either DNA fragmentation, cell proliferation, or colony formation. Immunoprecipitation showed that antisense-treated cells had reduced amounts of c-abl as compared to the untreated cells. When stimulated with lipopolysaccharide (LPS), 70Z/3 cells underwent proliferation and differentiation. When antisense oligonucleotides against type IV were added to the cell cultures, with LPS stimulation, induction of apoptosis continued to occur. When antisense oligonucleotides against type I were added in the cultures, in the presence of LPS, cell differentiation was inhibited, but cell proliferation continued to occur. This inhibition of differentiation was evident by a lack of immunoglobulin light chain production by cells that otherwise would produce immunoglobulin when they are stimulated with LPS. These data therefore show that type I c-abl allows cell differentiation to occur, whereas type IV c-abl suppresses apoptosis.

Animals↗
PubMed1996

Body composition differences between Polynesians and Caucasians assessed by bioelectrical impedance.

OBJECTIVE: To assess differences in body composition between Polynesians and Caucasians subjects. SUBJECTS: 48 male and 80 female Polynesians from a village in Rarotonga, Cook islands (81% response rate) and representative sample of 243 male and 250 female Caucasians from Melbourne, Australia. MEASUREMENTS: Body mass index, resistance from bioelectrical impedance, percent body fat derived from 4 equations using resistance, weight, height, age and sex. RESULTS: Male and female Polynesians were younger (by 7.7 years, P < 0.001 and 4.1 years, P < 0.05) and heavier (by 10.7 kg and 12.5 kg, P < 0.0001) than their Caucasian counterparts. Electrical resistance was significantly lower in Polynesians of both sexes by over 130 omega (P < 0.0001). At every level of weight (adjusted for height and age), resistance was lower in the Polynesians (P < 0.0001) and at every level of body mass index, the predicted body fat from 4 different equations was lower in Polynesians (P < 0.0001). CONCLUSIONS: These results imply that, at any given body size. Polynesians are significantly leaner than Caucasians and that specific Polynesian standards for defining obesity need to be developed. The findings will need to be confirmed by other reference methods for measuring body composition.

Adipose Tissue↗
PubMed1995

The Na(+)-translocating ATPase of Acetobacterium woodii is a F1F0-type enzyme as deduced from the primary structure of its beta, gamma and epsilon subunits.

A 4.5 kbp EcoRI fragment hybridizing to a fragment of uncD (coding for subunit beta of F1F0-ATPases) was cloned from chromosomal DNA of Acetobacterium woodii. The nucleotide sequence was determined and revealed five open reading frames (ORF), four of which were identified to code for subunits of the Na(+)-ATPase. The deduced amino acid sequences of these ORF's are homologous to subunit alpha (partial coding sequence, C-terminal end), gamma, beta and epsilon of F1F0-ATPases from various organisms; furthermore, the organization of the genes in the order uncA (alpha), uncG (gamma), uncD (beta), uncC (epsilon) is identical to the structure of unc operon as present in most bacteria. Downstream of uncC is an ORF whose deduced amino acid sequence has 53% sequence homology to AlgD from Pseudomonas aeruginosa. The structure and organization of the unc genes are the final proof that the Na(+)-ATPase from A. woodii is a member of the family of F1F0-ATPases.

Acetobacter↗
PubMed1995

Deregulation of c-abl mediated cell growth after retroviral transfer and expression of antisense sequences.

To determine the role of c-abl during cell growth, we constructed a retrovirus vector alpha A, capable of expressing an antisense RNA directed against the abl mRNA. Based on v-abl-mediated 3T3 transformation assay, we showed that the number of transformed foci was reduced 50-94% when alpha A-infected 3T3 cells were superinfected with A-MuLV. Up to a 100% of inhibition could be observed when the time of infection was lengthened. Introduction of the antisense sequence into NIH3T3 cells resulted in reduction of growth rate. These cells entered into S phase from G1 phase of the cell cycle earlier in time than untransduced cells. Thus c-abl serves as a checkpoint during G1/S transition in the cell cycle, and its reduction resulted in deregulation of cell growth.

3T3 Cells↗
PubMed1995

Biochemical and molecular characterization of the oxidative branch of glycerol utilization by Citrobacter freundii.

Glycerol dehydrogenase (EC 1.1.1.6) and dihydroxyacetone kinase (EC 2.7.1.29) were purified from Citrobacter freundii. The dehydrogenase is a hexamer of a polypeptide of 43,000 Da. The enzyme exhibited a rather broad substrate specificity, but glycerol was the preferred substrate in the physiological direction. The apparent Kms of the enzyme for glycerol and NAD+ were 1.27 mM and 57 microM, respectively. The kinase is a dimer of a polypeptide of 57,000 Da. The enzyme was highly specific for the substrates dihydroxyacetone and ATP; the apparent Kms were 30 and 70 microM, respectively. The DNA region which contained the genes encoding glycerol dehydrogenase (dhaD) and dihydroxyacetone kinase (dhaK) was cloned and sequenced. Both genes were identified by N-terminal sequence comparison. The deduced dhaD gene product (365 amino acids) exhibited high degrees of homology to glycerol dehydrogenases from other organisms and less homology to type III alcohol dehydrogenases, whereas the dhaK gene product (552 amino acids) revealed no significant homology to any other protein in the databases. A large gene (dhaR) of 1,929 bp was found downstream from dhaD. The deduced gene product (641 amino acids) showed significant similarities to members of the sigma 54 bacterial enhancer-binding protein family.

Amino Acid Sequence↗
PubMed1995

Purification of 1,3-propanediol dehydrogenase from Citrobacter freundii and cloning, sequencing, and overexpression of the corresponding gene in Escherichia coli.

1,3-Propanediol dehydrogenase (EC 1.1.1.202) was purified to homogeneity from Citrobacter freundii grown anaerobically on glycerol in continuous culture. The enzyme is an octamer of a polypeptide of 43,400 Da. When tested as a dehydrogenase, the enzyme was most active with substrates containing two primary alcohol groups separated by one or two carbon atoms. In the physiological direction, 3-hydroxypropionaldehyde was the preferred substrate. The apparent Km values of the enzyme for 3-hydroxypropionaldehyde and NADH were 140 and 33 microM, respectively. The enzyme was inhibited by chelators of divalent cations but could be reactivated by the addition of Fe2+. The dhaT gene, encoding the 1,3-propanediol dehydrogenase, was cloned, and its nucleotide sequence (1,164 bp) was determined. The deduced dhaT gene product (387 amino acids, 41,324 Da) showed a high level of similarity to a novel family (type III) of alcohol dehydrogenases. The dhaT gene was overexpressed in Escherichia coli 274-fold by using the T7 RNA polymerase/promoter system.

Alcohol Dehydrogenase↗
PubMed1994

A review of childhood admission with perforating ocular injuries in a hospital in north-west India.

A retrospective study of perforating ocular injuries in children below the age of fifteen years was conducted. Eighty patients (eighty-nine eyes) were included in this study. Male children were more susceptible to ocular injury as compared to females (p = < 0.01). Children of the school-going age were the most affected (73.8%). Majority of the injuries occurred in the sports field (p = < 0.01). Playing with bow and arrow, and gillidanda* accounted for majority of the sport injuries (47.2%). Sixty-eight percent of the perforated eyes had no light perception at the end of treatment. Health education on the preventive aspects of ocular injuries in schools as well as through mass media should reduce the incidence of visual loss due to ocular injuries.

Adolescent↗
PubMed1994

Refractive errors in preterm babies.

Fifty preterm neonates were followed up at the age of 6 months and 1 year. In addition to developmental assessment, a complete ophthalmological examination was done on both visits. The largest (62%) gestational age group was of 34-36 weeks. At 6 months, none of the infants had normal vision. At 1 year of age, 64% of the babies had normal vision while incidence of myopia and hypermetropia was 16% and 20%, respectively. There was an inverse relationship noted between gestation and incidence of refractive errors. It was also noted that with decreasing weight, the incidence of myopia increased. Myopia was seen exclusively among infants of birth weight of 2000 g or less. Birth weight had a significant positive correlation with astigmatism. No correlation of asphyxia with refractive errors was observed. It is recommended that all preterm babies should have an ophthalmological examination at one year of age with follow up later on.

Anisometropia↗
PubMed1993

[Common variable hypogammaglobulinemia. A rare cause of chronic diarrhea. A case].

In patients with chronic diarrhoea investigations exceptionally reveal a common variable hypogammaglobulinaemia. A 42-year old man presenting with chronic bronchitis and asymptomatic post-hepatitis B cirrhosis was hospitalized for evaluation of a chronic diarrhoea accompanied by altered general condition. Investigations detected global hypogammaglobulinaemia, diffuse lymphoid hyperplasia of the small bowel, and lambliasis. Treatment with gammaglobulins and antibiotics resulted in disappearance of symptoms. This was a rare disease due to a primary disorder where global hypogammaglobulinaemia was associated with a normal number of circulating B-cells. Prognosis was cautious in view of the risk of malignant proliferation.

Adult↗
PubMed1993

Characterization of a chelator-resistant proteinase from Thermus strain Rt4A2.

The Thermus isolate Rt4A2 was found to produce an extracellular chelator-resistant proteinase. The proteinase was purified to homogeneity by (NH4)2SO4 precipitation, cation-exchange chromatography, gel-filtration chromatography, and weak anion-exchange chromatography. The Rt4A2 proteinase was found to have properties typical of an alkaline serine proteinase. It had a pH optimum of 9.0 and was specifically inhibited by phenylmethanesulphonyl fluoride. Its isoelectric point was greater than 10.25. Its molecular-mass was 31.6 kDa as determined by SDS/PAGE. N-terminal sequencing has shown it to have high sequence similarity with other serine proteinases from Thermus species. The proteinase hydrolysed a number of substrates including fibrin, casein, haemoglobin, collagen, albumin and the synthetic chromogenic peptide substrate Suc-Ala-Ala-Pro-Phe-NH-Np. The specific activity of the purified proteinase using azocasein as substrate was 313 units/mg. Substrate inhibition was observed above an azocasein concentration of 0.05% (w/v). Esterase activity was directed mainly towards those substrates containing the aliphatic or aromatic residues of alanine, glycine, tryptophan, tyrosine and phenylalanine. Thermostability half-lives of greater than 7 days at 70 degrees C, 43 h at 80 degrees C and 90 min at 90 degrees C were found in the presence of 5 mM CaCl2. At 90 degrees C increasing the CaCl2 concentration 100-fold (0.5 mM to 50 mM) caused a 4.3-fold increase in the half-life of the enzyme from 30 to 130 min. Half-lives of 19.4 min at 100 degrees C and 4.4 min at 105 degrees C were found in the presence of 50 mM CaCl2. The metal chelators EGTA and EDTA reduced the stability at higher temperatures but had no effect on the activity of the proteinase. Activity was not stimulated by common metal activators such as Ca2+, Mg2+ and Zn2+.

Amino Acid Sequence↗
PubMed1993

Regulation of two members of the steroid-inducible cytochrome P450 subfamily (3A) in rats.

Monoclonal antibodies have been successfully isolated which are isozyme-specific for cytochrome P450p (3A1) or P4501 (3A2), two members of the steroid-inducible cytochrome P450 subfamily exhibiting 89% amino acid sequence homology, and these antibodies show less than 5% cross-reaction with 11 other cytochromes P450 (P450a-P450k). A library of 28 purified monoclonal antibodies was established and characterized as to epitope specificity. Appropriate antibodies were selected and utilized to investigate the regulation of expressed cytochrome P450p and P4501 proteins as a function of age, sex, and treatment of rats with various inducing agents. Cytochrome P450p is not detectable in hepatic microsomes from untreated immature or adult male and female rats. Following dexamethasone treatment, expression of cytochrome P450p is observed in all groups with the levels reaching 30-37% of total microsomal cytochrome P450. Administration of other inducers such as pregnenolone 16 alpha-carbonitrile also yield enhanced levels of cytochrome P450p. Measurable amounts of constitutive cytochrome P4501 were detected in hepatic microsomes from immature and adult males as well as immature females but not in adult females. Cytochrome P4501 expression is inducible by dexamethasone in immature rats of both sexes and adult males, although dexamethasone is more effective as an inducer of cytochrome P450p than cytochrome P4501. Hence, not only is cytochrome P4501 protein expressed in immature animals of both sexes, it is also inducible in both sexes. These studies show that constitutive expression and induction of steroid-inducible cytochrome P450s may vary as a function of age.

Age Factors↗
PubMed1993

Human papillomavirus in primary epithelial tumors of the lacrimal sac.

BACKGROUND: The lacrimal sac epithelium can give rise to benign and malignant neoplasms. Human papillomavirus (HPV) infection is known to be causal in the development of epithelial neoplasias elsewhere in the body. The authors have examined primary lacrimal sac tumors for the presence of HPV. METHODS: Nine primary lacrimal sac tumors (3 benign papillomas and 6 carcinomas) submitted to the Eye Pathology Laboratories at the Wilmer Institute between 1960 and 1991 were examined for the presence of HPV sequences by in situ hybridization and the polymerase chain reaction (PCR). RESULTS: Of the nine tumors, only six were suitable for analysis by PCR or in situ hybridization. All three papillomas were positive for HPV type 11. Three of the carcinomas were positive for HPV sequences, and one case could be further characterized as HPV type 18. CONCLUSIONS: Human papillomaviruses appear to be involved in the genesis of both benign and malignant neoplasms of the lacrimal sac epithelium. As in the genital tract, HPV type 11 is associated with benign lesions, whereas HPV type 18 is associated with malignancy.

Adult↗
PubMed1993

Vulvar vestibulitis is rarely associated with human papillomavirus infection types 6, 11, 16, or 18.

Vulvar vestibular biopsy specimens from 31 women with clinical and pathologic findings of vulvar vestibulitis were studied using polymerase chain reaction (PCR) for the identification of human papilloma virus (HPV). The PCR technique specifically probed for HPV types 6, 11, 16, and 18. Of the 31 subjects, three were found to have HPV within the biopsy specimens; two had HPV type 11 and one had HPV 16. Five of the 31 cases had histopathologic features of koilocytosis consistent with HPV effect; three of these five were found to have HPV. The findings support the hypothesis that HPV types 6, 11, 16, and 18 are rarely associated with vulvar vestibulitis. The frequencies identified were similar to those seen with control patients. True koilocytosis is the most useful pathologic feature distinguishing HPV-related cases; it is rarely identified in typical vulvar vestibulitis. Nonspecific changes in the vestibular epithelium associated with glycogen effect should not be interpreted as koilocytosis.

Adult↗