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Biomedical subjects

F Fuchs

Publications and source records attributed to F Fuchs.

At least 145 records · Page 8Linked to original sources
PubMed1977

The binding of calcium to glycerinated muscle fibers in rigor. The effect of filament overlap.

The binding of Ca2+ to glycerinated rabbit psoas fibers of varying sarcomere length was measured with a double isotope technique and ethyleneglycol-bis-(beta-aminoethylether)-N,N'-tetraacetic acid buffers. Experiments were carried out under rigor conditions with fiber bundles pre-set at different lengths prior to extraction with detergent and glycerol. These experiments were designed to test whether rigor complex formation, determined by the degree of filament overlap, enhances Ca2+-receptor affinity in the intact filament lattice, as it does in reconstituted actomyosin systems. The Ca2+-receptor affinity, as indicated by the free Ca2+ concentration at half-saturation and by the slopes of Scatchard plots, was found to be relatively unaffected by variations in filament overlap. However, the maximum bound Ca2+ was significantly reduced in stretched fibers. With maximum filament overlap the bound Ca2+ was equivalent to 4 mol per mol troponin. When stretched to zero overlap the fibers bound a maximum of 3 mol Ca2+ per mol troponin. When fibers with maximum overlap were incubated in the presence of 5 mM MgATP there was a reduction in the number of Ca2+-binding sites equivalent to that caused by stretching the fibers. These findings, taken together with other data in the literature, suggest that in the intact filament lattice at least one of the Ca2+-binding sites is present only when cross-bridge attachments are formed.

Animals↗
PubMed1977

Inhibition of premature labor: a multicenter comparison of ritodrine and ethanol.

A randomized controlled study was carried out at three medical centers to compare the efficacy and side effects of ethanol and ritodrine in the treatment of threatened premature labor. One hundred and thirty-five patients judged to be between the twentieth and thirty-sixth week of gestation and presenting with clinical symptoms of premature labor were included. Sixty-seven patients were treated with intravenous infusion of 10 per cent ethanol. Sixty-eight patients were treated with intravenous infusion of ritodrine for 12 hours followed by oral ritodrine. If labor recurred prematurely, up to two additional courses of ethanol or ritodrine were given. Delivery was postponed for more than 72 hours in 49 of 67 patients (73 per cent) with ethanol and in 61 of 68 patients (90 per cent) with ritodrine; this difference was significant. Patients in the ethanol group gained a mean of 27.6 days while patients in the ritodrine group gained a mean of 44.0 days. Fifty-four per cent of the ethanol group and 72 per cent of the ritodrine group carried their infants to 36 weeks of gestation. Five infants in the ethanol group and one infant in the ritodrine group died from respiratory distress syndrome. The most frequent side effect of ethanol were nausea and vomiting. The most frequent side effects of ritodrine were tachycardia and blood pressure changes which were easily controlled by lowering the infusion rate. Ethanol and ritodrine were both found to be effective inhibitors of premature labor with ritodrine giving the most favorable results.

Adult↗
PubMed1976

Prevention of prematurity.

Although only about 8 per cent of pregnancies end prematurely, as much as 75 per cent of perinatal deaths are due to prematurity. Since it is difficult to identify the predisposing factors in individual cases and to prevent the premature onset of labor, it is necessary to try to arrest such labor when it occurs. A theoretical scheme for the mechanism of labor in the human subject is presented. This permits the identification of four possible points of attack: (1) replacement of progesterone to reduce the myometrial sensitivity to oxytocin, (2) administration of beta-mimetic agents to relax the uterus and make it unresponsive to stimuli, (3) administration of ethanol to block oxytocin secretion, and (4) administration of anti-inflammatory drugs to inhibit prostaglandin synthesis. Results obtained with ritodrine, a beta-mimetic agent, and with ethanol are presented as illustration. Ritodrine gave somewhat better results than ethanol, possibly because the treatment was continued after discharge of the patients.

Adrenergic beta-Agonists↗
PubMed1976

Cooperative binding of calcium to glycerinated skeletal muscle fibers.

The binding of 45Ca2+ to glycerinated rabbit psoas fibers was measured by means of a double isotope technique. With 5 mM Mg2+ (no ATP) binding was half-maximal at 1.4-10(-6) M Ca2+ and the maximal amount bound was 1.6 mumol/g protein. At less than 50% saturation, the Scatchard plot had a positive slope and the Hill coefficient was 2.2. At greater than 50% saturation, the Scatchard plot was linear with a negative slope (K' = 0.8 - (10(6) M-1) and the Hill coefficient was 1.0. In the absence of Mg2+, binding was half-maximal at 3 - 10(-7) M Ca2+ and the maximal amount bound was 2.9 mumol/g protein. The Scatchard plot indicated two classes of sites with K' values of about 2 - 10(7) and 2 - 10(6) M-1. The Hill coefficient in the mid-saturation range was approx. 0.6. The data indicate that in the presence of the Mg2+ binding to about half of the total Ca2+ binding sites is suppressed and there is a strong positive cooperativity involving half of the ramaining sites.

Animals↗
PubMed1976

Demonstration of gonadotropin during the second half of the cycle in women using intrauterine contraception.

A highly sensitive pregnancy test based upon partial purification of urinary gonadotropins by Sephadex gel filtration and concentration of the gonadotropin-containing fraction by lyophilization has been developed. Values over 100 I.U. per liter after Day 22 are considered to indicate conception. They are verified by radioimmunoassay (RIA) of the beta-subunit of human chorionic gonadotropin (HCG) in plasma. Urine samples from users of intrauterine contraception were examined at random. Among samples collected after Day 21, 14 contained more than 100 I.U. per liter. In three of these cases, RIA of the beta-subunit HCG in plasma was employed and verified the results. The results support the hypothesis that intrauterine contraception interferes with implantation and establishment of pregnancy but not with fertilization and blastocyst formation.

Chorionic Gonadotropin↗
PubMed1976

Tubal and uterine motility in vivo in the rhesus monkey.

Previous data indicate that there are definite qualitative and quantitative patterns of tubal activity during the various phases of the menstrual cycle. In the present investigation, the simultaneous activity of the uterus and Fallopian tube was recorded in vivo in mature rhesus monkeys throughout the menstrual cycle. The observations indicate that there are characteristic patterns of both tubal and uterine activity, depending on the various phases of the menstrual cycle. The simultaneous recordings of tubal and uterine activity show that the tubal and uterine contractions are not synchronous or even have a similar pattern. The presence of a transmetrial catheter for recording of uterine activity seems to modify the patterns of tubal activity, particularly during the ovulatory phase. It seems possible that the transmetrial catheter has a similar effect as an intrauterine contraceptive device in this species.

Animals↗
PubMed1976

Preparation of parenchymal and non-parenchymal cells from adult human liver--morphological and biochemical characteristics.

By perfusion of the isolated human liver with collagenase and hyaluronidase a mixed suspension of various cell types was obtained. Pure parenchymal cells were prepared by differential centrifugation, pure non-parenchymal cells by the use of pronase and subsequent isopycnic centrifugation on metrizamide gradients (50-300 g/l). About 90% of the parenchymal and non-parenchymal cells were viable as judged by trypan blue staining. Non-parenchymal cells were not capable fo gluconeogenesis but at high rates. Parenchymal cells retained their ability to form glucose and to accumulate glycogen from fructose greater than lactate/pyruvate greater than alanine. Studies on binding of 125I-labelled insulin by isolated parenchymal cells were performed at 30 degrees C. The binding data may fit with a minimum of two classes of binding sites: (a) high affinity--low capacity sties (Kd approximately 6.6 nmol/l, capacity approximately 16 000 insulin molecules per cell) and (b) low affinity-high capacity sites (Kd approsimately 0.37 mumol/l, capacity approximately 646 000 molecules per cell).

Adult↗
PubMed1975

The effect of berotec (Th 1165a) on spontaneous and induced uterine activity in the pregnant baboon.

Berotec (Th 1165a), a specific beta-adrenergic agent, has been found to be a more potent agent than metaproterenol in the inhibition of uterine activity in animals and human beings. The effect of berotec on spontaneous (postinduced) and induced uterine activity in the pregnant baboon near term was investigated. Berotec administered intravenously in a dose of 5 mug per minute consistently and significantly reduced spontaneous uterine activity as well as uterine activity by either oxytocin or prostaglandin F2-alpha. The frequency of contractions was consistently reduced whereas the effect on the amplitude of contractions was less marked. There was no reduction of the baseline muscle tonus. Berotec infusion produced a marked increase in the maternal heart rate, averaging 40 beats per minute. Berotec appears to be a potent inhibitor of spontaneous, oxytocin-induced, and prostaglandin-induced uterine activity in the pregnant baboon, but it has considerable cardiovascular side effects.

Adrenergic beta-Agonists↗
PubMed1975

Thermal inactivation of the calcium regulatory mechanism of human skeletal muscle actomyosin: a possible contributing factor in the rigidity of malignant hyperthermia.

The muscular rigidity associated with anesthetically induced malignant hyperthermia has been attributed to an increase in myoplasmic free calcium concentration. However, previous in-vitro studies have shown that increased temperature can eliminate the calcium requirement for actin-myosin interaction. Therefore, the calcium dependency of human skeletal muscle actomyosin in response to temperature increases of the magnitude encountered in human muscle during hyperthermic episodes was investigated. Calcium dependency is expressed in terms of the ability of a calcium-chelating agent, EGTA, to inhibit the ATP-induced turbidity increase of actomyosin suspensions (superprecipitation). In the presence of millimolar concentrations of ATP and magnesium, EGTA completely inhibits superprecipitation at temperatures as high as 35 C. With further increase in temperature this inhibition is progressively reduced until, at 45 C, the extent of superprecipitation is independent of the calcium concentration. Loss of calcium control is potentiated by reduction in the ATP concentration. Since the muscular rigidity of malignant hyperthermia is associated with both an elevation of muscle temperature and a decline in muscle ATP content, it is evident that in this disorder conditions might exist for an increase in muscle tension that is independent of changes in intracellular free calcium concentration.

Actomyosin↗
PubMed1975

Perforation of the uterus by the copper-t and copper-7 intrauterine contraceptive devices.

Uterine perforation in patients wearing the Copper-T and the Copper-7 intrauterine contraceptive devices has been studied. In Bollnäs, Sweden, three perforations occurred in 1 156 insertions of the Copper-7, and in New York, USA, six perforations occurred in 1 153 insertions of the Copper-T. Cervical perforation seems to be a special feature of the Copper-T, while the Copper-7 tends to perforate through the uterine wall. The perforations can be divided into "primary" perforations, related to the insertion procedure, and "secondary" perforations, caused by uterine contractions. The diagnosis and treatment of uterine perforations by intrauterine devices is discussed.

Adult↗
PubMed1975

Comparison of three intrauterine contraceptive devices: the Antigon-F, the Ypsilon-Y, and the Copper-T 200.

A comparative study of three intrauterine contraceptive devices, the Antigon-F, the Copper-T, and the Ypsilon-Y, was carried out at The New York Hospital Cornell Medical Center during an 18-month period from March 1, 1972, through August 31, 1973. At the cutoff date of February 28, 1974, all patients had been followed for at least 6 months. During the period of study, 884 Antigon-F devices, representing 14,436 woman-months of use, were inserted. The over-all pregnancy rate was 0.88, with an explusion rate of 5.1 and a medical removal rate of 9.1/100 woman-years. This device was best tolerated by multiparous women. There was a total of 910 insertions of the Ypilson-Y, representing 14,348 woman-months of use. The over-all pregnancy rate was 1.8, with an explusion rate of 1.9 and a medical removal rate of 3.7/100 woman-years. The pregnancy rate in nulliparous women was 0.78, with a continuation rate of 88.9. The pregnancy rate in multiparous woman was higher, i.e., 2.4. Nine hundred thirty-nine Copper-T 200 devices, representing 15,558 woman-months, were inserted. The over-all pregnancy rate was 0.85, with an expulsion rate of 1.8, a medical removal rate of 4.5, and a continuation rate of 88.4/100 woman-years. The pregnancy rate was 0.82 for nulliparous women and slightly higher, i.e., 1.04, for multiparous women. Thus, all three devices had considerable merit. The Antigon-F and the Copper-T seemed the best in multiparous women; the Ypsilon-Y in the size used was best in nulliparous women. The only perforations occurred with the Copper-T.

Copper↗