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Biomedical subjects

A Darabi

Publications and source records attributed to A Darabi.

12 recordsLinked to original sources
PubMed1995

Differential gene expression in experimental hepatocellular carcinoma induced by woodchuck hepatitis B virus.

Hepatitis B virus infection is closely linked to hepatocellular carcinoma (HCC), the pathological mechanism of hepatocarcinogenesis by this virus is not well understood. In order to gain further insight into the molecular mechanism of HCC, we constructed and screened a subtracted c-DNA library which was specific to HCC cells of a woodchuck infected with woodchuck hepatitis B virus. Among eight clones that were isolated based on their differential expressions, we determined nucleotide sequences of two genes whose expressions were most significantly stimulated in HCC. Our results indicate that these two genes appear to be woodchuck counterpart genes of hemopexin (HPX) and alpha-1 acid glycoprotein (AGP), suggesting that the expression of HPX and AGP genes are strongly augmented in tumor cells partly due to transcriptional regulation.

Amino Acid Sequence↗
PubMed1992

Florida Department of Corrections' substance abuse programs.

The Florida Department of Corrections has worked diligently to plan and implement a system of comprehensive institutional and community-based programs. These programs strive to establish a functional, cost-effective continuum of care for incarcerated individuals while providing necessary linkages essential to transferring inmates back into society with the knowledge and social skills necessary to lead a drug-free life. It is believed that a viable working model has been developed that will offer inmate services and, ultimately, afford them the opportunity and appropriate linkages to continue treatment as needed after incarceration.

Florida↗
PubMed1990

Characterization of membrane-associated actin in boar spermatozoa.

Biochemical, immunological, and electron microscopic methods have been used to provide semi-quantitative estimates and to localize actin in membranes of boar spermatozoa. Immunoblots, using a monoclonal antibody raised against actin from chicken gizzard, detected the protein in caput and cauda sperm plasma membranes. Immunoassay indicated that approximately 1% of the total plasma membrane protein was actin. Monomeric actin accounted for more than one-half of the membrane actin. Approximately 30-40% of plasma membrane actin was insoluble in Triton X-100, and approximately 10% of the total actin remained insoluble after treatment with guanidine hydrochloride. The presence of F-actin in sperm plasma membranes and in plasma membrane detergent-insoluble proteins was detected by fluorescence microscopy using the specific probe NBD phallacidin. When S1 myosin subfragments attached to colloidal gold were used to localize F-actin by electron microscopy, the label was restricted to the outer acrosomal membrane of intact epididymal and ejaculated sperm. Filaments appeared in short arrays along the anterior region of the membrane. S1/gold labeled detergent-insoluble plasma membrane fractions but did not label the plasma membrane in intact sperm. Filaments were least prominent in intact caput spermatozoa and most prominent in ejaculated spermatozoa. We conclude that most actin associated with sperm membranes is in monomeric form in boar spermatozoa, but that actin filaments or protofilaments are components of the outer acrosomal membrane. These filaments may also associate with the plasma membrane overlying the acrosome.

Acrosome↗
PubMed1990

Mutational analysis of enhancer domains responsive to trans-activation by the X gene of human hepatitis B virus.

The X gene product of human hepatitis B virus (HBV) trans-activates the HBV enhancer. In order to identify domains responsive to trans-activation by the X gene, we introduced a series of mutations into the HBV enhancer and assayed the enhancer activities in the presence of the X gene product. Our results suggest that the EP domain of the enhancer is essential for trans-activation by the X gene.

Base Sequence↗
PubMed1990

Organ-specific distribution of isozymes of 5'-nucleotide phosphodiesterase in mouse.

1. The distribution of isozymes of 5'-nucleotide phosphodiesterase (E.C.3.1.4.1) was examined in various organs of mouse, including liver, spleen, pancreas, heart, lung, kidney, brain and blood. 2. Five isozymes were identified and designated as isozymes I through V. 3. These isozymes are distributed unevenly with respect to the various organs and clear differences were observed in the patterns of distribution among the organs examined. 4. The level of these isozymes was compared in serum of neonate and adult mice, and a higher level of isozyme I and a lower level of isozyme IV were found in neonates compared to adults. 5. These results suggest that each isozyme has different functional roles in individual organs and that these isozymes may be involved in proliferation and development of cells.

Animals↗
PubMed1989

Identification and nucleotide sequence of the minimal replicon of the low-copy-number plasmid pBS2.

The plasmid pBS2 has a low copy number and is endogenous to Bacillus subtilis. The replication of this plasmid depends on the function of most of the host's dna genes including dnaB, which is unique to B. subtilis and is required for both the initiation of chromosome replication and the DNA-membrane association. We have identified the region that is essential for the replication of pBS2 and determined the complete 2279-bp nucleotide sequence of this region. In this region, there are two stretches of sequence homologous to the 18-bp consensus sequence which commonly appears at the origin of replication of plasmids pUB110 and pC194. The entire region contains six sizable open reading frames. Two of them are probably translated. One open reading frame, designated ORF A, coding for 269 amino acids, has significant homology, in terms of amino acid sequence, with the open reading frame of the gene for the Rep U protein of plasmid pUB110. The similarities between pBS2 and other plasmids suggest that the pBS2 may also replicate as a rolling circle, which appears to be the salient feature of a mechanism of replication that is common to small plasmids in gram-positive bacteria.

Amino Acid Sequence↗
PubMed1987

The role of bacterial virulence factors and Tamm-Horsfall protein in the pathogenesis of Escherichia coli urinary tract infection in infants.

Forty-three patients and 70 controls were enrolled in an open study to evaluate the role of bacterial virulence factors and Tamm-Horsfall protein (THP) in the pathogenesis of urinary tract infection (UTI) due to Escherichia coli. The ages of the patients and controls ranged from 5 days to 6 months. Nine patients had upper UTIs and 33 patients had lower UTIs, based on bacteremia and radiographic evidence. There were no differences between patients and controls in the percentages of strains showing hemolytic activity of E coli strains isolated from periurethral and rectal cultures. Urinary E coli strains recovered from patients showed a significantly higher percentage of mannose-resistant hemagglutination, greater P and X fimbriation, more type 1 pili, and the presence of mannose-sensitive and mannose-resistant hemagglutination when compared with E coli strains recovered from the controls. The O but not the K pyelonephritogenic serotypes were more commonly recovered from patients than from controls. The mean THP concentrations in urine (micrograms of THP per milligrams of creatinine) were 29.9 and 91.4 micrograms/mg for patients and controls, respectively. With the exception of hemagglutination properties and certain pyelonephritogenic O serotypes, other virulence factors of E coli could not be defined in our infant population. The role of THP, if any, in the pathogenesis of UTI remains unresolved.

Escherichia coli↗
PubMed1987

Pharmacokinetics and plasma bactericidal activity of aztreonam in low-birth-weight infants.

Aztreonam (30 mg/kg) was administered intravenously every 12 h during week 1 and every 8 h during weeks 2 to 4 of life to 26 low-birth-weight (less than 2,000 g) infants, and plasma concentration-time curves were measured on two occasions. The pharmacokinetics were described equally well by one-compartment and noncompartment models, and the values on day 1 were similar to those measured during the steady state on days 3 to 6. The mean peak plasma concentrations at completion of the 10-min infusion were from 65 to 83 micrograms/ml, the higher concentrations being seen in the larger infants. The half-lives of aztreonam ranged from 5.4 to 8.6 h and did not change significantly with birth weight. The median peak and trough plasma bactericidal titer against a strain of Escherichia coli (MBC, 10 micrograms/ml) was 1:16. Against a strain of Pseudomonas aeruginosa (MBC, 16 micrograms/ml), the median peak and trough bactericidal titers were 1:8 to 1:16 and 1:4, respectively. The urinary concentrations of aztreonam on day 1 of therapy were from 24 to 460.7 micrograms/ml (mean +/- 1 standard deviation, 254 +/- 113 micrograms/ml).

Aztreonam↗