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Biomedical subjects

R Engel

Publications and source records attributed to R Engel.

At least 73 records · Page 4Linked to original sources
PubMed1986

Quantitation of trans-vitamin K1 in small serum samples by off-line multidimensional liquid chromatography.

A sensitive high-performance liquid chromatography method for vitamin K1 using normal-phase fractionation was updated in order to cope with the limited volume of blood samples obtained from newborns. The method combines sample clean-up, normal-phase fractionation with reversed-phase chromatography using post-column electrochemical reduction and fluorescence detection. It was possible to measure vitamin K1 concentration in at least 0.2 ml of (potentially lipemic) serum even at a level of 0.3 nmol/l. The normal-phase method was compared to the updated method. The updated method shows about a twenty-fold lower limit of detectability than the previously described method.

Chromatography, High Pressure Liquid↗
PubMed1986

A complex translocation in a 5-year-old boy with acute myeloblastic leukemia.

A complex translocation [t(2;10;11)(q34;q11;q13)], an extra chromosome #8, and a duplication of 17q were the major findings in blast cells found in the bone marrow of a 5-yr-old boy with AML-M2 both before treatment and during relapse. The child died 8.5 mo after diagnosis, despite intensive combination chemotherapy.

Child, Preschool↗
PubMed1986

(11; 14) translocation in three boys with acute lymphoblastic leukemia of T-cell immunophenotype.

Three boys, 12, 15 and 5 years old are presented with acute lymphoblastic leukemia resp. Non-Hodgkin's lymphoma with leukemic transformation. Blast cells could be characterized as being of T-cell origin. Hand mirror variant was the predominant morphologic feature of the blast cells in two patients. Chromosome analysis of the leukemic blast cells revealed a pseudodiploid (modal chromosome number = 46) karyotype in two patients and a pseudotetraploid (modal chromosome number = 92) in one patient. A chromosome translocation (11; 14) with breakpoints at (p 13; q 13) (within the human T-cell receptor alpha chain locus!) was found in the leukemic cells of all three cases plus an additional t (7; 9) (q 22; p 13) in one patient.

Adolescent↗
PubMed1984

Correlation of 3,4-dihydroxybutyl 1-phosphonate resistance with a defect in cardiolipin synthesis in Escherichia coli.

Escherichia coli treated for 1 h with 100 microM rac-3,4-dihydroxybutyl 1-phosphonate (DBP), a glycerol-3-phosphate analog, die when sorted at 5 degrees C, whereas the viability of untreated cells is relatively unaffected. This observation formed the basis of a selection procedure that was used to isolate mutants that are partially resistant to DBP. One such mutant, strain 6204, is constitutive for DBP transport, exhibits a particularly high degree of cold resistance, has the same doubling time as the parent, and is similar to the parent strain in terms of incorporation of DBP into the lipid fraction. Glycerol-3-phosphate and phosphatidylglycerol phosphate synthetases obtained from strain 6204 and its parent were identical in terms of DBP recognition. The parent strain is killed when incubated in the presence of a combination of 70 microM rac-DBP and 0.25% deoxycholate, whereas strain 6204 continues to grow, albeit more slowly, in the presence of this combination. Strain 6204 can be distinguished from the parent strain on agar plates (low phosphate minimal medium with glucuronate as the sole carbon source) containing 15 microM rac-DBP. The insertion of Tn10 near the 6204 mutation has facilitated genetic manipulations. All phenotypic effects attributed to strain 6204 appear to be due to a single mutation. Genetic analysis indicates that Tn10, inserted near the gene responsible for DBP resistance, maps in the vicinity of 27 min. Three-factor crosses reveal a gene order of hemA-Dbpr-Tn10(zch)-trp. The only gene for phosphoglyceride metabolism known to map in this region is the gene associated with cardiolipin synthetase, cls. Genetic results suggest that the mutation responsible for DBP resistance maps in or very near cls. Analysis of the lipids isolated from untreated strain 6204 (and from each of the transductants prepared by P1 vir-mediated transfer of DBP resistance of wild-type strains) reveals that cardiolipin synthesis is defective. These results strongly suggest that the mutation responsible for DBP resistance has its primary effect on cardiolipin synthesis. To further test this hypothesis, strains with an authentic cls mutation were constructed and examined for resistance to DBP. These strains had growth properties that were identical with those of strain 6204. Wild-type strains and mutants defective in cardiolipin synthesis were treated with DBP and 20 mM magnesium or calcium chloride. Simultaneous treatment of either cell type with DBP and divalent cation not only failed to stimulate growth but, quite the contrary, had a marked synergistic growth inhibitory effect.

Butylene Glycols↗
PubMed1983

Studies on chemically induced rat tumors. II. Partial protection against syngeneic lethal tumors by cloned syngeneic cytotoxic T lymphocytes.

In the present article we describe studies on a chemically induced sarcoma in DA rats. This tumor expresses a unique antigen which can be demonstrated by both syngeneic antibodies and cytotoxic T cells. We have established cytotoxic T-cell lines (CTLs) specific for the tumor and with high efficient killing capacity in vitro. When testing for the ability of such CTLs to inhibit tumor out-growth in vivo, we found that they had to be inoculated together with the tumor and in the presence of T-cell growth factor to provide any significant degree of protection. We thus believe not only that there is a requirement for addition of CTL-stimulating lymphokines in vivo, but also that the CTLs fail to move from one site in vivo to attack relevant tumor cells at another site. No evidence was obtained that the CTLs gradually could acquire such migratory ability in vivo.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed1983

Red cell membrane abnormalities in two cases with a special type of a hereditary megaloblastoid hemolytic anemia.

Case reports are presented of two related patients suffering from a hereditary megaloblastoid hemolytic anemia which at the moment cannot be categorized into one of the well-known entities. The main characteristics of the disease consisted of constant jaundice, macrocytic normochromic anemia, marked hemolysis without a substantial decrease in osmotic resistance, increased iron turnover and hepatic hemosiderosis at a relatively young age. One patient had to undergo splenectomy due to hemolytic crises, the other one cholecystectomy due to gallstones. In contrast to their uncharacteristic morphology in smear, red cells displayed highly variable forms ("lumpy", "Y", "U", drumstick forms) when examined in transmission and scanning electron microscopes. These changes corresponded well with reduced filtrability and aggregability of erythrocytes. The apparent relative blood viscosity was unchanged. The protein pattern of ghosts in SDS gel-electrophoresis revealed neither defects nor additional bands. Changes in the lipid composition of the membrane were indirectly deduced from electron spin-resonance studies, which showed an additional signal at g = 2.192. Similarly, the lipid related membrane mobility agent A2C failed to exert the usual stabilizing effect against osmotic stress. The negative surface potential, estimated by free flow electrophoresis, was only altered in the splenectomized patient. It is concluded that the primary abnormal physical properties of the enlarged red cell contribute at least in part to the marked hemolysis. The similar findings in the two related patients and the fact that the disorder was obviously congenital suggest a special subtype of a megaloblastoid hemolytic anemia.

Adolescent↗
PubMed1982

The menisci of the lumbar zygapophysial joints.

In a study of 82 lumbar zygapophysial joints three types of intra-articular structures were identified. They were adipose tissue pads and fibro-adipose meniscoids, both located at the superior and inferior poles of the joint, and connective tissue rims, located along the dorsal and ventral margins. Every lumbar zygapophysial joint contained at least one of these structures and 47 contained more than one type. Connective tissue rims are short, central projections of the joint capsule and do not enter between the articular surfaces. Adipose tissue pads are covered by synovium and fill the subcapsular space at the superoventral and inferodorsal poles of the joint. Fibro-adipose meniscoids, also covered by synovium, project from the joint capsule at the superior and inferior poles and enter between the articular surfaces. Adipose tissue pads and fibro-adipose meniscoids are probably derived from a common primitive mesenchymal meniscus which primarily differentiates into a fatty structure. The fibrous component of fibro-adipose meniscoids then secondarily develops as a result of compression of the tip of the fatty structure between the articular surfaces. The function of these intra-articular structures is not evident but may be related to protection of the articular processes as they subluxate during flexion and extension. Meniscus entrapment in the lumbar zygapophysial joints has been proposed as a cause of acute locked back, but the present morphological data are inconsistent with this view.

Adipose Tissue↗
PubMed1981

EEG pattern in phenylketonuria under early initiated dietary treatment.

Nineteen of 161 infants with a confirmed diagnosis of phenylketonuria (PKU) had initially abnormal EEGs obtained within days of diagnosis. The abnormalities consisted of single repetitive or multiple spikes and/or sharp waves, focal or scattered, which rarely occurred in paroxysmal bursts. Initial maximal diagnostic serum phenylalanine (Phe) levels were significantly higher for the group with abnormal EEGs. The mean diagnostic serum Phe level was 56 mg/dL in the group with abnormal EEGs, whereas the mean diagnostic Phe level was 48 mg/dL in the group with normal tracings. The average age at initiation of restrictive dietary treatment was approximately 3 weeks. The initially abnormal EEGs became normal by 1 year of age in all but two patients who had a minimal and a mild abnormality, respectively. Hypsarrhythmic patterns were not seen. Infants with PKU detected early and treated well do not appear to need routine EEG monitoring.

Brain↗
PubMed1981

Nephrogenic adenoma: clinical features and therapeutic considerations.

Nephrogenic adenoma is a benign metaplastic lesion that usually responds to endoscopic treatment. Although occasionally it has been present simultaneously with another malignancy there has been no evidence that a nephrogenic adenoma has ever transformed into a carcinoma. The symptoms of a nephrogenic adenoma can be severe but these lesions can be treated with transurethral surgery. The lesions can occur throughout the bladder and in the urethra. They usually are associated with trauma to the urothelium. Postoperative followup is needed because these lesions tend to have a symptomatic recurrence. An increased awareness of nephrogenic adenoma by urologists and pathologists may lead to its more frequent diagnosis.

Adenoma↗
PubMed1980

Effect of 3,4-dihydroxybutyl-1-phosphonate on phosphoglyceride and lipoteichoic acid synthesis in Bacillus subtilis.

3,4-Dihydroxybutyl-1-phosphonate (CH2OHCHOHCH2CH2PO3HPO3H2), an analogue of glycerol 3-phosphate, preferentially inhibits the rate of synthesis and accumulation of phosphatidylglycerol in Bacillus subtilis W23 and 168. The rate of phosphatidylethanolamine synthesis is only slightly inhibited, whereas that of lysylphosphatidylglycerol is somewhat stimulated. As expected, decreased phosphatidylglycerol synthesis results in the inhibition of the formation of the putative lipoteichoic acid precursor, sn-glycero-1-phospho-beta-gentiobiosyldiacyglycerol and of lipoteichoic acid itself.

Bacillus subtilis↗
PubMed1979

Glycerol 3-phosphate analogues as metabolic inhibitors in Escherichia coli, 3-hydroxy-4-oxobutyl-1-phosphonate, a drug that interferes with normal phosphoglyceride metabolism.

3-Hydroxy-4-oxobutyl-1-phosphonate, the phoshonic acid analogue of glyceraldehyde 3-phosphate, enters Escherichia coli via the glycerol 3-phosphate transport system. There is no differential effect upon the accumulation of deoxyribonucleic acid, ribonucleic acid, or phosphoglycerides, although the accumulation of proteins was less effected. Examination of the phospholipids revealed that phosphatidylglycerol accumulation was most severely inhibited and cardiolipin accumulation was least affected. Concentrations of glyceraldehyde 3-phosphate and its phosphonic acid analogue that markedly inhibit macromolecular and phosphoglyceride biosynthesis have no effect upon the intracellular nucleoside triphosphate pool size. The phosphonate is a competitive inhibitor of sn-glycerol 3-phosphate in reactions catalyzed by acyl coenzyme A:sn-glycerol-3-phosphate acyltransferase and CDP-diacylglycerol:sn-glycerol-3-phosphate phosphatidyltransferase. A Km mutant for the former enzyme was susceptible to the phosphansferase activity. Studies with mutant strains ruled out the aerobic glycerol-3-phosphate dehydrogenase, glycerol-3-phosphate synthase, and fructose-1,6-biphosphate aldolase as the primary sites of action.

Bacterial Proteins↗
PubMed1979

Biosynthesis of murein lipoprotein in Escherichia coli: effects of 3,4-dihydroxybutyl-1-phosphonate.

The effects of 3,4-dihydroxybutyl-1-phosphonate, a four-carbon analog of sn-glycerol 3-phosphate, on the biosynthesis of the glyceryl moiety in murein lipoprotein of Escherichia coli were studied. The compound at a concentration of 55 microM strong inhibits in the incorporation of [2-3H]glycerol radioactivity into lipoprotein by virtue of its inhibition of the synthesis of phosphatidylglycerol. On the other hand, the incorporation of prelabeled [2-3H]glycerol radioactivity into lipoprotein was only partially inhbited by 3,4-dihydroxybutyl-1-phosphonate even at a much higher concentration (1 mM). These data were consistent with the postulated pathway for the biosynthesis of the lipid moiety in lipoportein: cysteine-lipoprotein + phosphatidylglycerol leads to glycerylcystein-lipoprotein + phosphatidic acid.

Bacterial Proteins↗
PubMed1979

Rhythmometry gauges treatment of mesor-hypertension in the seventh and eight decades of life.

Autorhythmometry of blood pressure by an individual over an age-span of 67 to 72 years showed a strong circadian rhythm superimposed upon significant circaseptan and circannual rhythms. Automatic BP monitoring with an Arteriosonde throughout 24-hour spans on 4 separate occasions, before and during treatment, also indicated a prominent circadian BP rhythm and a treatment-related reduction in circadian mesor. The concept of a blood pressure mesor reference for the antimesor-hypertensive treatment constitutes a valuable guideline in the control of "familial" mesor-hypertension.

Aged↗
PubMed1978

The effect of chronic ACTH treatment on blood pressure and urinary excretion of steroids in the rat.

The effects of subcutaneous injections of synthetic ACTH during 14 subsequent days has been studied in the rat. ACTH caused a loss in body weight which was related to a negative water balance. Blood pressure rose rapidly and reached values higher than 180 mm Hg in all rats after 10 days of ACTH administration. During this period, urinary excretion of corticosterone and 18-hydroxy-deoxycorticosterone (18-OH-DOC) was increased more than ten times, while aldosterone excretion was increased only during the first two days. After withdrawal of ACTH, excretion of steroids normalized, or in some cases was even suppressed and water balance and body weight gain returned to normal values. However, blood pressure remained slightly higher than in controls after ten days. The effects of ACTH on water balance and blood pressure resemble those of corticosterone in the rat. The rapidly induced and sustained changes in blood pressure by ACTH administration suggest that this may be an useful model of experimental hypertension.

18-Hydroxycorticosterone↗