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Biomedical subjects

D Birnbaum

Publications and source records attributed to D Birnbaum.

At least 271 records · Page 15Linked to original sources
PubMed1988

Nullisomic deletion of the mcf.2 transforming gene in two haemophilia B patients.

The mcf.2 transforming gene sequence has been located to the region between 29 and 61 kb 3' of the factor IX gene. Two unrelated haemophilia B patients who raise antibodies to infused factor IX ('inhibitors') have deletions in excess of 273 kb encompassing the factor IX and mcf.2 genes and a CG-rich island. We believe these patients show the first nullisomic deletion of a transforming gene to be reported. No clinical condition can be attributed to the loss of the mcf.2 gene.

Blotting, Southern↗
PubMed1988

Regulation of metabolic branch points of aromatic amino acid biosynthesis in Pichia guilliermondii.

The regulatory properties of the enzymes involved in the aromatic amino acid biosynthesis of Pichia guilliermondii were investigated and compared with the regulatory pattern found in other yeast species. 3-Deoxy-D-arabino-heptulosonate-7-phosphate (DAHP) synthase, anthranilate synthase, chorismate mutase and prephenate dehydrogenase are key regulatory enzymes in P. guilliermondii. Two distinctly regulated isozymes of DAHP synthase, the initial pathway enzyme, which is inhibited by tyrosine or phenylalanine were separated by DEAE-cellulose chromatography and were characterized. Tryptophan is an excellent feedback inhibitor of anthranilate synthase, the first definite step in tryptophan biosynthesis. There are two controlled enzymes within the specific synthesis of phenylalanine and tyrosine, chorismate mutase and prephenate dehydrogenase. Chorismate mutase exhibits a balanced allosteric responsivity to phenylalanine and tyrosine, when these are used as inhibitor; tryptophan acts as an allosteric activator. Tyrosine is an effective inhibitor of prephenate dehydrogenase, whereas the activity of prephenate dehydratase is not affected by any of the aromatic amino acids. The synthesis of the enzymes in the yeast was not repressed by any single exogenous aromatic amino acids, nor by combinations of the same.

3-Deoxy-7-Phosphoheptulonate Synthase↗
PubMed1988

ST segment monitoring before, three weeks and six months after aortocoronary bypass surgery.

ST segment monitoring by Holter ECG was conducted in 80 consecutive patients 2-4 weeks before aortocoronary bypass surgery and three weeks and six months after surgery. Preoperatively, all patients were under maximal medical therapy. In 31 out of 80 patients medical therapy could be stopped and thus 24-h ST monitoring could also be conducted without medication. Preoperative and early postoperative (three weeks) examinations were performed under hospital conditions. At 6 months after surgery the patients were monitored at home during their everyday activities. Twenty-eight per cent of patients waiting for aortocoronary bypass surgery under full medication showed transient ischaemic episodes in 24-h Holter ECG. Seventy-eight per cent of these episodes were asymptomatic. Without medication, 55% of patients had transient ischaemia. The exercise ECG data partly predicted the Holter ECG data. Patients with ST segment depression greater than 0.1 mV during exercise ECG had on Holter monitoring more and longer lasting ischaemic episodes than those with ST segment depression less than or equal to 0.1 mV. In patients with asymptomatic ST segment depression during exercise ECG the relation of silent episodes to symptomatic episodes on Holter monitoring was 5.3:1 while in patients with symptomatic ST segment depression during exercise ECG this relation was 2.3:1. Three weeks after operation the informative value of the Holter ECG was very restricted due to changes in the resting ECG caused by the operation and because patients do not exert themselves much at this time. Six months after surgery, Holter ECG is more informative, especially when conducted at home.(ABSTRACT TRUNCATED AT 250 WORDS)

Coronary Artery Bypass↗
PubMed1988

Transcranial Doppler ultrasonography during cardiopulmonary bypass in patients with severe carotid stenosis or occlusion.

Blood flow velocity of the middle cerebral artery was monitored during cardiopulmonary bypass procedures by means of transcranial Doppler ultrasonography. Our investigation was carried out in a group of 16 patients with severe carotid stenosis or occlusion and in a control group of 42 patients with no or stenosis of less than 50% local diameter reduction. After onset of cardiopulmonary bypass, both groups showed a short unstable phase followed by increased blood flow velocity (10% increase ipsilateral to the obstruction, 27% increase in the control group). Just before rewarming, blood flow velocity was still comparable to (control group -3%) or higher than (ipsilateral to obstructions +14%) prebypass values. Analysis of three patients with postoperative diffuse encephalopathy did not reveal reduced blood flow during cardiopulmonary bypass as a relevant factor. Two of the three showed luxury perfusion. Reduced perfusion due to carotid obstruction was not observed during cardiopulmonary bypass and therefore cannot be considered a significant risk factor for the development of intraoperative stroke.

Adult↗
PubMed1988

The FGF-related oncogenes hst and int.2, and the bcl.1 locus are contained within one megabase in band q13 of chromosome 11, while the fgf.5 oncogene maps to 4q21.

Prompted by the observed co-amplification at the DNA level of the int.2 and hst fibroblast growth factor-related oncogenes in some tumor cells, we have investigated the precise localization of these two loci known to reside in band q13 of chromosome 11. We demonstrate by pulsed field gel analysis that these two genes are separated by only 40 kb, locate three HTF islands in their neighbourhood, and show that the bcl.1 locus (translocation breakpoint in B-cell proliferative malignancies) is not more than 1050 kb away. We also show that the fgf.5 gene which belongs to the same family is not part of this cluster and is located in band q21 of chromosome 4.

Cell Line↗
PubMed1988

Activation of a mcf.2 oncogene by deletion of amino-terminal coding sequences.

The mcf.2 transforming sequence was previously identified by tumorigenicity-assay of the mammary carcinoma cell line MCF-7, molecularly cloned and localized to Xq27 by in situ hybridization. cDNA clones representing both the activated gene and the corresponding portion of its normal counterpart were isolated and their nucleotide sequence determined. Sequence analysis showed that the mcf.2 gene was activated by rearrangement and loss of 5' sequences and no other alteration. Comparison of the mcf.2 nucleotide sequence with the recently published dbl sequence (Eva, A., G. Vecchio, D. Rao, S. Tronick & S. Aaronson (1988) Proc. Natl. Acad. Sci. USA, 85, 2061-2065) revealed that mcf.2 and dbl represent two different activated versions of the same proto-oncogene.

Amino Acid Sequence↗
PubMed1988

[Surgical indications in asymptomatic internal carotid artery stenosis and in relation to heart surgery interventions].

In the last 30 years, carotid endarterectomy has been employed on a wide-spread basis with the intention of providing surgical prophylaxis of stroke. Currently, however, there is no evidence available from prospective, randomized comparative studies indicating a clear superiority of surgical treatment versus medical treatment with respect to stroke prophylaxis or improvement in survival. Based on recent publications with sufficiently large patient populations, operative mortality appears to be about 1% and the rate of perioperative stroke about 3.4%. In those with symptomatic internal carotid stenosis, without surgery there is a 5% yearly risk of cerebral infarction such that carotid endarterectomy possibly appears warranted. In contrast, in association with asymptomatic internal carotid stenosis, that is, in the absence of any symptoms indicative of cerebral hypoperfusion, based on several recent prospective studies, the yearly rate of cerebral infarction is 1 to 2% and, consequently, less than that of the prophylactic surgical intervention. Additionally, carotid endarterectomy does not render complete protection against stroke and the follow-up curves for the respective treatments do not differ meaningfully, even during longterm observation. Accordingly, for asymptomatic internal carotid stenosis, the indication for surgery has not been clearly established. Among those with asymptomatic carotid stenosis, there may be a subgroup of individuals with high-grade luminal obstruction or multiple vessel disease, who according to several studies, appear to be at a higher risk of subsequent complications even though this has not yet been confirmed by prospective, randomized studies.(ABSTRACT TRUNCATED AT 250 WORDS)

Carotid Artery Diseases↗
PubMed1988

Detection of transforming sequences in human melanomas and leukemias.

DNA extracted from fresh solid human melanoma tumors and untreated acute myeloid leukemic cells was used in two assays designed to detect oncogenes, based on the transfection of murine NIH 3T3 fibroblasts followed by selection of transformed cells in low serum concentration or induction of tumors in athymic mice. Ras and non-ras oncogenes were detected.

Animals↗
PubMed1988

[Primary atrial heart tumors--a review of 21 cases].

Between 1978 and 1986, atrial heart tumors were found in 21 of our patients, all of them subsequently underwent surgery. Pathological-histological examination in 20 patients confirmed the diagnosis of a myxoma; the one remaining case was a female patient with primary cardiogenic osteosarcoma. Of the 20 patients, 15 (75%) were females; in four female patients (20%) the tumor was localized in the right atrium. The main symptoms and findings were elevated erythrocyte sedimentation rates (80%), stress-induced dyspnea or paroxysmal dyspnea (71% resp.), and diastolic mitral or tricuspid murmurs (62%). The patient with osteosarcoma died of cachexia on the basis of generalized diffuse metastases. One female patient with a preoperative history of severe left ventricular impairment on the basis of dilative cardiomyopathy died 5 weeks after surgery. Relapse of atrial myxoma has not yet occurred during follow-up since 1978.

Adult↗
PubMed1988

Chromosomal localization of the hst oncogene and its co-amplification with the int.2 oncogene in a human melanoma.

In this report we described the linkage between two oncogenes of the fibroblast growth factor family. Using in situ hybridization to human metaphase chromosomes we mapped the hst gene to chromosome 11 at band q13. This is also the location of the int.2 gene. Furthermore, the two genes are co-amplified in a human melanoma, raising the possibility that amplification in human tumors may be a mechanism of activation of genes of the FGF family.

Chromosome Mapping↗