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Biomedical subjects

A Goldfarb

Publications and source records attributed to A Goldfarb.

At least 127 records · Page 7Linked to original sources
PubMed1984

Changed promoter specificity and antitermination properties displayed in vitro by bacteriophage T4-modified RNA polymerase.

A 5.5 X 10(3) base-pair fragment of bacteriophage T4 DNA carrying genes 1, 3, 57, ipI and a cluster of transfer RNA genes was used as template for RNA polymerase isolated from uninfected Escherichia coli and from T4-infected bacteria. RNA transcripts were fractionated by gel electrophoresis and mapped by using as transcription template the 5.5 X 10(3) base fragment cleaved with different restriction enzymes. The comparison of the transcripts synthesized by the two RNA polymerases revealed a dramatic difference in their initiation specificities and abilities to utilize a transcription termination site. The T4-modified polymerase utilizes three new promoters on the template DNA fragment that are not utilized by the host enzyme. The modified enzyme, however, fails to produce some of the transcripts synthesized by the host RNA polymerase. The ability of T4-modified RNA polymerase to terminate transcription at a terminator present in the template DNA fragment is greatly reduced as compared to the unmodified host enzyme. The factors responsible for the new initiation and termination properties are associated with RNA polymerase core component. Analysis of RNA polymerase from bacteria infected with T4 mutants demonstrates that the new promoter specificity and the antitermination effect are caused by different factors.

DNA Restriction Enzymes↗
PubMed1984

Human anti-pneumococci antibody produced by an Epstein Barr virus (EBV)-immortalized cell line.

Anti-pneumococcal antibody-producing lymphocytes from a patient who was immunized with Pneumovax (a polysaccharide mixture from 14 different pneumococci types) were selected and immortalized with Epstein Barr virus (EBV). The cells of the emerging cloned line were shown on a single cell level assay to secrete an IgM, kappa anti-pneumococci antibody. This human monoclonal antibody bound specifically to polysaccharides of pneumococci type 8, but did not bind to any of the other 13 pneumococci types that were present in the Pneumovax mixture. In competition experiments, inhibition of binding occurred with polysaccharide type 8 and Pneumovax only. This diploid cell line has actively secreted the specific antibody (2.8 micrograms/10(6) cells/ml) now for more than 9 mo. In patients, increased anti-pneumococcal antibody titers generated by active immunization with Pneumovax improves resistance to the corresponding bacterial infection. Production in vitro of human monoclonal antibodies directed toward bacterial and viral antigens enables a new possible approach for passive immune protection.

Antibodies, Bacterial↗
PubMed1984

[Prenatal ultrasonic diagnosis of malformation uropathies: 13 cases].

The systematic prenatal diagnosis of 5 cases of urinary tract malformations out of 2 500 pregnancies in 1982 in a special care maternity, or 2 per 1 000 is compared with the discovery of 10 cases in 28 months in 17 960 foetuses, or 0.55 per 1 000 whereas the overall frequency varies from 0.3 to 5.25 per 1 000 in infants. We studied 13 children whose prenatal abnormalities were 2 unilateral ureterohydronephrosis and 7 bilateral dilatations associated to 2 ureteroceles, 1 multicystic dysplasia and 1 ureteral duplicity. All of these except two were confirmed at birth. The exceptions consisted in one unilateral dilatation and one bilateral ureterohydronephrosis which turned out to be dysplastic kidneys unknown during pregnancy. Three ureteral duplicities were also ignored. The results are the following: Three cases were severe: one therapeutic abortion after 27 weeks, one intra-uterine decompression followed after few days by a preterm delivery and neonatal death and one provocated preterm delivery (36 weeks). All the others underwent decompression during the first hours of their life. Five cases can be considered unsuccessful: 2 abortions, the death of a 22 days old infant with an unilateral multicystic dysplasia and 2 bilateral malformations with renal failure, one of which was associated to an unilateral dysplastic kidney. Reliability of sonography as well as its interest in prognosis and prenatal evaluation of renal function are demonstrated.

Amniotic Fluid↗
PubMed1983

Changes in the parotid salivary gland of beta-thalassemia patients due to hemosiderin deposits.

2 patients afflicted with beta-thalassemia major presented with pain and swelling of the parotid salivary gland. In 1 patient, the symptoms were of long standing and particularly severe, with diminished and highly viscous salivation. In the other patient, the parotid glands had only recently become painful, while salivary output and quality remained normal. The parotid anatomy in both patients, as demonstrated by sialography, and the clearance of opaque material were normal. Tc99 scintigraphy revealed reduced uptake and rapid clearance of the isotope from the parotid serous glands into the oral cavity, in contrast to the increased uptake by the sublingual mucous glands. Iron deposits were demonstrated in the parotid secretory serous cells. It is postulated that the impaired function of the parotid is linked to iron deposits in the serous cells of this gland, as a sequella of beta-thalassemia.

Adolescent↗
PubMed1983

Myelofibrosis in young adults.

3 young adults with myelofibrosis, a rare disease in this age-group, are presented. Their clinical course was distinguished by a virtually asymptomatic state at time of diagnosis and a stable, or very slowly progressive course over a 4- to 5-year follow-up. Myelofibrosis in young adults may pursue a more benign course than that usually noted in older populations.

Adult↗
PubMed1983

[Solitary upper incisor, hypopituitarism and monosomy 18p chromosome aberration].

A prepubertal boy with hypopituitarism, mental retardation, dysmorphia and solitary maxillary central incisor is described, karyotypic studies showed deletion of the short arm of chromosome 18 (46, XY, del (18) (p11). It is suggested that caryotypic studies is of interest among the patients with midline defects and/or hypopituitarism.

Child↗
PubMed1983

[Panhypopituitarism in one of 2 monozygotic twins].

Anterior panhypopituitarism has been observed in one of monozygous twin girls. Etiologic investigations were negative and only suggested an hypothetic perinatal insult. Genetic abnormalities could be excluded. Replacement therapy with human growth hormone was strikingly successful, with a remarkable catch-up growth and, however, a velocity of bone age comparable with the velocity of growth.

Age Determination by Skeleton↗
PubMed1982

Tumour of the nose as a presenting feature of leukaemia.

A skin nodule on the external nose, as a presenting feature of acute myeloid leukemia, is described. The child presented with a lesion on the tip of the nose together with the clinical and haematologic features of leukaemia. The histological finding of the nodule was found to be a characteristic leukaemia cutis with leukaemia cell infiltrate in the skin. Epistaxis and external ear infection were also additional features of E.N.T. system involvement, as we find in other leukaemic patients. Since starting chemotherapy the patient has been well, in complete remission, and the lesion on the nose has almost disappeared.

Adolescent↗
PubMed1982

Use of Denver shunt in recurrent hepatic hydrothorax.

A 49-year-old woman with alcoholic cirrhosis was hospitalized for severe respiratory distress. A moderate amount of ascites was noted on physical examination, and the right hemithorax was completely opacified on the chest x-ray film. Thoracentesis was performed, and a follow-up chest x-ray film showed marked reduction of pleural effusion. Two days later the patient again was in respiratory distress, and a chest tube was inserted. On the tenth hospital day, a peritoneovenous (Denver) shunt was inserted and the chest tube was removed. Follow-up chest x-ray films showed almost complete resolution of pleural effusion, and the patient has remained free of symptoms. When hepatic hydrothorax does not respond to conventional therapy, we believe aggressive treatment with a Denver shunt may be successful. To our knowledge this procedure has been performed successfully in only one other patient. Further study is needed to assess its value as a possible alternative method of treatment.

Female↗
PubMed1982

Circulating erythroid progenitors in patients with 'spent' polycythaemia vera and myelofibrosis with myeloid metaplasia.

The ability of circulating progenitor cells from patients with polycythaemia vera (PV) and myelofibrosis with myeloid metaplasia (MMM) to develop erythroid colonies was studied in cultures with and without erythropoietin. In all normal controls, patients with secondary polycythaemia and MMM, erythroid colonies developed only after the addition of erythropoietin. Only in patients with PV, both in the active and spent phases of the disease, erythroid colonies developed in the absence of erythropoietin. The results indicate the perpetuation of erythropoietin-dependent, as well as erythropoietin-independent progenitors in both phases of this disease. Although spent PV often clinically resembles MMM, there is a basic difference in the behaviour of the circulating erythroid progenitors in these diseases which may serve as a useful tool in discriminating MMM from spent PV, when there is no history of active PV.

Adult↗
PubMed1981

Control of promoter utilization by bacteriophage T4-induced modification of RNA polymerase alpha subunit.

After infection of Escherichia coli cells, bacteriophage T4 induces several changes in the host DNA-dependent RNA polymerase. A well-characterized chemical change is a two-step ADP-ribosylation of the enzyme's alpha subunit (1). In order to investigate the effect of this change on RNA polymerase transcriptional properties in an in vitro system, we have reconstituted the enzyme from separated individual subunits which were obtained from normal or T4-modified RNA polymerases. It is demonstrated that the enzymes containing T4-modified alpha differ from the enzymes with normal alpha in two respects: (i) their overall activity on T4 DNA is reduced and (ii) they fail to utilize certain T4 promotors while efficiently utilizing other promoters. Among the promoters which are switched off by alpha modification are the two promoters of the D region and one of the two promoters of the T4 tRNA gene cluster. The differential effect of alpha modification on the expression of the tRNA and the D regions in vitro correlates with the previously established pattern of their transcription in vivo. It is suggested that the T4-induced ADP-ribosylation of RNA polymerase alpha subunit is involved in the shutoff of the early bacteriophage genes at the late stage of phage development.

DNA-Directed RNA Polymerases↗
PubMed1981

Mapping of in vitro transcription units and identification of primary transcripts of the D region of bacteriophage T4.

The D region of bacteriophage T4 is comprised of six closely linked genes which are situated between 161 kb and 165 kb on the T4 chromosome. We studied the transcription of these genes in vitro by using DNA templates derived from a series of deletion mutants in this region. The mixture of primary products made by Escherichia coli RNA polymerase were fractionated by gel electrophoresis into discrete RNA species. The results obtained together with the known map positions of the deletions allowed to identify four wild-type and several deletion-specific transcripts of the D region. The end points of these transcripts were approximately mapped. The results demonstrate that the D region has two promoters and two terminators, an organisation which is similar to the previously established organisation of the T4 tRNA gene cluster.

DNA, Viral↗
PubMed1981

IN vitro transcription of bacteriophage T4 tRNA gene cluster from two different promoters.

Analysis of primary transcripts made by Escherichia coli RNA polymerase on T4 DNA containing an intact or partially deleted tRNA gene cluster demonstrates that the T4 tRNA genes are transcribed from two promoters differing in their strength. The stronger (P1) and the weaker (P2) promoters are located at distances of 1 kb and 1.5 kb from the tRNA genes, respectively. Selective initiation of individual transcripts with dinucleotides shows that P1 and P2 promoters contain the sequences TAT and CAC respectively. The two-promoter organisation of the tRNA cluster may reflect two superimposed mechanisms of gene expression in T4-infected bacteria.

Chromosome Mapping↗