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Biomedical subjects

M Marx

Publications and source records attributed to M Marx.

At least 37 records · Page 2Linked to original sources
PubMed1989

Short-duration, high-dose urokinase infusion for recanalization of occluded saphenous aortocoronary bypass grafts.

Thrombolytic recanalization of arterial bypass grafts has been pursued aggressively in the peripheral circulation but not in the coronary circulation. In an attempt to apply peripheral transcatheter thrombolytic techniques to the coronary circulation, nine patients with 10 occluded saphenous aortocoronary bypass grafts underwent recanalization procedures using a short-duration, high-dose urokinase infusion. Urokinase was infused at the occluded graft orifice at a rate of 600 units/min. The average infusion time was 1 hr, 26 min. The average urokinase dose was 435,000 units. Graft recanalization was achieved in eight (80%) of 10 grafts, although only six (60%) of 10 grafts were widely patent at the end of the procedure. All successfully recanalized grafts required balloon angioplasty of underlying stenoses. No complications, specifically myocardial infarction or cerebrovascular accident, were encountered. We have shown that occluded aortocoronary bypass grafts can be recanalized successfully by using a short-duration, high-dose urokinase infusion. It appears that, with attention given to angiographic techniques that minimize clot manipulation, recanalization can be accomplished safely in a majority of cases.

Adult↗
PubMed1988

Stable propagation of the active transcriptional state of an immunoglobulin mu gene requires continuous enhancer function.

Enhancer sequences control the expression of the immunoglobulin mu heavy chain gene. In this study we examined whether the active transcriptional state of the mu gene can be propagated from mother to daughter cells after deletion of its enhancer. A mu gene that contains the enhancer flanked by D and J recombination signals was stably introduced into pre-B cells, resulting in mu gene transcription. Subsequent deletion of the enhancer from the transfected gene by D-to-J joining reproducibly resulted in switching off of mu expression. Moreover, transcriptional inactivation occurred although the mu gene was found to be hypomethylated prior to deletion of the enhancer. We conclude that the enhancer does not confer upon the mu gene "memory" of its active transcriptional state. Thus, the enhancer seems to be required both for establishment and for maintenance of mu gene expression.

Base Sequence↗
PubMed1988

[Plasma thiocyanate determination: a simple method for quantifying the smoking habits of pregnant patients--a preliminary study].

Plasma thiocyanate (SCN) was measured by means of a simple colorimetric method [8] in 328 persons (175 males, 153 females, aged 5-68 years) as part of an ongoing prospective trial on the influence of SCN defined maternal smoking on fetal development. The interassay coefficient of variation for synthetic K thiocyanate solutions was 3.1% (n = 25%); the intrassay coefficient of variation was 1.2% (n = 15). Mean SCN levels were significantly lower in 226 nonsmokers (SCN 41.4 +/- 18.5 mumol/l) than 102 smokers (SCN 81.4 +/- 28.7 mumol/l; p less than 0.01). Of all the variables tested, a direct influence on SCN was found only in the case of diabetes mellitus and haemolytic blood samples (p less than 0.01), whereas age, sex, chronic diseases and nutrition had no effect on SCN. Mean maternal post partum SCN levels (n = 48) were significantly lower in non-smokers (30.2 +/- 11.2) than in smokers (59.3 +/- 23.1). There was a linear relationship between maternal venous plasma and fetal umbilical cord plasma SCN values (r = 0.88; p less than 0.01). Pregnant women had lower SCN levels than non-pregnant women. We conclude that SCN is an easy means of measuring and a reproducible parameter for quantifying smoking behaviour in pregnancy and in the general population.

Adolescent↗
PubMed1988

A novel oncogene related to c-mil is transduced in chicken neuroretina cells induced to proliferate by infection with an avian lymphomatosis virus.

Non-dividing neuroretina cells from chicken embryos are induced to proliferate after a long latency, following infection with Rous associated virus type 1, an avian retrovirus which does not carry a transforming gene. We have isolated from these proliferating cells an acutely mitogenic retrovirus, designated IC10, which contains a novel oncogene. Nucleotide sequencing showed that the IC10 virus has transduced 1101 nucleotides of cellular origin inserted between the gag and env genes of RAV-1. This oncogene, designated v-Rmil, is 70.1% homologous to v-mil. v-Rmil encodes a protein of 40,976 daltons sharing 83.8% homology with the catalytic domain of the v-mil protein. Divergence with the v-mil gene product is observed at the NH2- and COOH-terminal portions of the v-Rmil protein. Restriction analysis of normal chicken DNA indicated that v-Rmil is derived from a cellular gene distinct from c-mil. The c-Rmil gene is transcribed through a major mRNA, greater than 10 kb in length, that is detected at much higher levels in neuroretinas, as compared to other embryonic tissues.

Amino Acid Sequence↗
PubMed1988

The effects of various indwelling ureteral catheter materials on the normal canine ureter.

In an attempt to objectively evaluate the biocompatibility of materials commonly used for ureteral stenting, stent-catheters made of four different materials were placed randomly in 31 ureters of 19 mongrel dogs. Animals underwent urography at four weeks and were sacrificed at six weeks. Mild hydronephrosis was noted in eight instances, essentially unrelated to specific material. Silicone, C-flex and polyurethane stents caused a similar, mild degree of ureteral edema, but ureters stented with Silitek demonstrated fairly marked edema. Epithelial ulceration and erosion, often severe, occurred with all polyurethane stents, and rarely with the three other materials. All materials differed statistically from controls, and C-flex caused less reaction overall than polyurethane, indicating differences in biocompatibility of the various materials which may be relevant to their use in patients undergoing long-term ureteral stenting. In practical terms, these suggest that certain materials, notably silicone and C-flex, are more suitable for ureteral stenting than others.

Animals↗
PubMed1988

Activation and transduction of c-mil sequences in chicken neuroretina cells induced to proliferate by infection with avian lymphomatosis virus.

We report that nondividing neuroretina cells from chicken embryos can be induced to proliferate following infection with Rous-associated virus type 1 (RAV-1), an avian lymphomatosis retrovirus lacking transforming genes. Multiplication of RAV-1-infected neuroretina cells is observed after a long latency period and takes place initially in a small number of cells. We also show that serial virus passaging onto fresh neuroretina cultures leads to the generation of novel mitogenic viruses containing the mil oncogene. DNA analysis indicated that RAV-1 is the only provirus detected in cells infected at virus passage 1, whereas neuroretina cells infected at subsequent virus passages harbor mil-containing proviruses. Three viruses, designated IC1, IC2, and IC3, were molecularly cloned. Restriction mapping indicated that in each virus, truncated c-mil sequences were inserted within different portions of the RAV-1 genome. In addition, IC1 and IC2 viruses have transduced novel sequences that belong to the 3' noncoding portion of the c-mil locus. All three viruses induce neuroretina cell multiplication and direct the synthesis of mil-specific proteins. Proliferation of neuroretina cells infected at passage 1 of RAV-1 was not associated with any detectable rearrangement of c-mil, when a v-mil probe was used. However, these cells expressed high levels of an aberrant 2.8-kilobase mRNA hybridizing to mil but not to a long terminal repeat probe. Therefore, transcriptional activation of a portion of c-mil could represent the initial events induced by RAV-1 infection and lead to retroviral transduction of activated c-mil sequences.

Animals↗
PubMed1987

N-terminal deletion in the src gene of Rous sarcoma virus results in synthesis of a 45,000-Mr protein with mitogenic activity.

Expression of the v-src gene of Rous sarcoma virus in avian embryo neuroretina cells results in transformation and sustained proliferation of these normally resting cells. Transformed neuroretina cells are also tumorigenic upon inoculation into immunodeficient hosts. We have previously described conditional mutants of Rous sarcoma virus encoding p60v-src proteins which induce proliferation of neuroretina cells in the absence of transformation and tumorigenicity. These results suggest that p60v-src is composed of functionally distinct domains which may interact with multiple cellular targets. In this study, we describe a spontaneous variant of Rous sarcoma virus, subgroup E, which carries a deletion of 278 base pairs in the 5' portion of the v-src gene but which has retained the ability to induce proliferation of quail neuroretina cells. The deleted v-src gene encodes a 45,000-molecular-weight phosphoprotein which contains both phosphoserine and phosphotyrosine, is myristylated, and possesses tyrosine kinase activity indistinguishable from that of wild-type p60v-src. Molecular cloning and sequence analysis of the mutant v-src gene have shown that this deletion extends from amino acid 33 to 126 of the wild-type p60v-src. Therefore, this portion of the v-src protein is dispensable for the mitogenic activity of Rous sarcoma virus in neuroretina cells.

Animals↗
PubMed1987

Rous sarcoma virus mutant dlPA105 induces different transformed phenotypes in quail embryonic fibroblasts and neuroretina cells.

dlPA105 is a spontaneous variant of Rous sarcoma virus, subgroup E, which carries a deletion in the N-terminal portion of the v-src gene coding sequence. This virus was isolated on the basis of its ability to induce proliferation of quiescent quail neuroretina cells. The altered v-src gene encodes a phosphoprotein of 45,000 daltons which possesses tyrosine kinase activity. DNA sequencing of the mutant v-src gene has shown that deletion extends from amino acid 33 to 126 of wild-type p60v-src. We investigated the tumorigenic and transforming properties of this mutant virus. dlPA105 induced fibrosarcomas in quails with an incidence identical to that induced by wild-type virus. Quail neuroretina cells infected with the mutant virus were morphologically transformed and formed colonies in soft agar. In contrast, dlPA105 induced only limited morphological alterations in quail fibroblasts and was defective in promoting anchorage-independent growth of these cells. Synthesis and tyrosine kinase activity of the mutant p45v-src were similar in both cell types. These data indicate that the portion of the v-src protein deleted in p45v-src is dispensable for the mitogenic and tumorigenic properties of wild-type p60v-src, whereas it is required for in vitro transformation of fibroblasts. The ability of dlPA105 to induce different transformation phenotypes in quail fibroblasts and quail neuroretina cells is a property unique to this Rous sarcoma virus mutant and provides evidence for the existence of cell-type-specific response to v-src proteins.

Animals↗
PubMed1987

Compromised T-cell regulatory functions during anuran metamorphosis: the role of corticosteroids.

Glucocorticoid receptor concentrations, which are undetectable before metamorphosis, increase to a maximum during the metamorphic period and decline to toadlet levels thereafter. The generation of a high concentration of receptors, imparting enhanced glucocorticoid sensitivity particularly to the lymphoid tissues of metamorphic larvae suggests the possibility that increasing endogenous levels could be responsible for the compromised T-cell functions which have been described for these stages of development (Ruben et al, 1985a).

Adrenal Cortex Hormones↗
PubMed1987

Treatment of hamster pancreatic cancer with alpha-difluoromethylornithine, an inhibitor of polyamine biosynthesis.

Polyamines are essential for cell division and growth. Inhibition of polyamine biosynthesis by alpha-difluoromethylornithine (DFMO) on the growth of hamster H2T pancreatic cancer was investigated both in vitro and in vivo. Cell-doubling time (TD) and survival fraction were determined after a single treatment with DFMO (5 mM). We examined the ability of putrescine to reverse the growth-inhibitory effect of DFMO. The TD for cells treated with DFMO in vitro was 49.6 +/- 5.7 versus 25.4 +/- 2.6 hours for control. The addition of putrescine to DFMO-treated H2T cells showed a reversal of the growth-inhibitory effect of DFMO. Cytotoxicity in vitro increased with prolonged treatment; the survival fraction after 24 hours of treatment was 32%; after 48 hours, 19%; after 72 hours, 13%; and after 92 hours, 8%. We performed two separate animal experiments. In experiment I, H2T cells were injected into the cheek pouch of male Syrian golden hamsters; controls did not receive DFMO. Continuous treatment with 3% DFMO in the drinking water was begun 7 days before, on the day of, or 7 days after tumor cell injection. In experiment II, 4 groups were treated identically to those in experiment I. An additional group of 10 hamsters received 3% DFMO and no tumor, and another additional group of 10 hamsters were housed individually with 3% DFMO begun 7 days after tumor cell injection. Tumor size, body weight, water, and food intake were measured. DFMO treatment in vivo significantly inhibited tumor size and inhibited growth of pancreatic cancer by as much as 50% of control. Our results demonstrate a significant antiproliferative effect of DFMO on the growth of pancreatic adenocarcinoma both in vitro and in vivo.

Adenocarcinoma↗
PubMed1986

Phosphorylation of microsome-bound cytochrome P-450 LM2.

The phosphorylation of a microsomal protein of rabbit liver by catalytic subunit of cyclic AMP-dependent protein kinase was shown, and the protein was identified as cytochrome P-450 LM2 on basis of comparative peptide-mapping. Acid hydrolysis of microsome-bound phosphorylated cytochrome P-450 revealed that phosphorylation occurred exclusively on serine residues. This serine residue was identified as the same residue phosphorylated in purified, soluble P-450, that is, serine in position 128.

Animals↗
PubMed1986

Temporal frequency-dependent VEP changes in Parkinson's disease.

We recorded steady-state (4.19 and 8.41 Hz) VEPs in 17 Parkinson's Disease (PD) patients and 18 control observers using on-off temporal modulation of a 2.3 c/deg sinusoidal grating. With 4.19 Hz, 20 out of 33 PD patient eyes had abnormal VEPs. However, only 8 of 33 eyes were abnormal with 8.41 Hz. "Routine" (counterphase) transient VEPs revealed delayed VEPs for only 7 out of 24 eyes of the patients. These findings suggest an "input" temporal frequency-dependent abnormality in the foveal pathway.

Adult↗
PubMed1986

Nuclear magnetic resonance spectroscopy of rat ventricles following supravalvar aortic banding. A model of left ventricular hypertrophy.

Left ventricular hypertrophy produced by supravalvar aortic banding in infant rats was studied by proton magnetic resonance spectroscopy. Weight gain at 11 weeks of age in the 11 male Sprague-Dawley rats with aortic bands placed at three weeks was similar to that of the 14 controls. The left ventricle of banded rats hypertrophied, increasing the ratio of left ventricle plus septum to body weight (LV + S/BW) by more than 50% (P less than .00001). Right ventricular weight (RV/BW) increased slightly (P less than .03). T1 and T2 relaxation times of LV + S, RV, and thigh muscle (Th) from the banded and control rats were compared. The T2 value distinguished hypertrophied from control LV + S (P less than .003), but not between RV or Th from the two groups. For banded rats only, the T2 value distinguished each muscle type: LV + S from RV, LV + S from Th, and RV from Th (P less than .00001 for each). For control rats, cardiac muscle was distinguished from Th (P less than .00001), but LV + S and RV were similar. The T1 value did not distinguish either the banded from the control group or any of the muscle types. Percent water content was similar for all tissues. Any correlation between water content and T1 or T2 was inconsistent or weak.

Animals↗