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At least 37 records · Page 2Linked to original sources
PubMed1979

In vitro perfusion studies of the human placenta. VI. Evidence against active glucose transport.

Previous studies in our laboratory using "in vitro" perfusion have established that glucose transport across the human placenta is a carrier-mediated process. It is not known whether these carriers require the expenditure of metabolic energy to function. In the experiments presented here we demonstrate in the perfused placenta that there is not reduction in the rate of glucose transport or its analogue 3-O-methyl-alpha-D-glucopyranoside (3MG) in the presence of 10(-4) M dinitrophenol (DNP), an uncoupler of oxidative phosphorylation. The presence of DNP, however, does cause an increase in the glucose utilization rate as well as increased lactic acid production. In order to test whether glucose transport depends on the functioning of a sodium pump system, the sodium in the perfusion system was replaced with choline chloride. The final sodium content was 30 mEq/L. In the presence of a low sodium concentration there was no decrease in the rate of 3MG transport compared to the control experiments run at normal sodium levels. Also "counter transport" of glucose was observed, a further indication that the glucose carrier mechanism does not require a sodium gradient in order to function. Since the transport rate of glucose or its analogue 3MG across the placenta is not reduced in the presence of 10(-4)M DNP and is not reduced in the absence of a sodium gradient, it is unlikely that the mechanism of glucose transport is an active process requiring the expenditure of metabolic energy.

Adult↗
PubMed1979

Trochanter bone marrow: a source of normal human colony forming cells.

In vitro studies of human hemopoiesis are often limited by the availability of normal bone marrow. We have overcome this difficulty by taking advantage of the bone marrow fragments removed during total hip replacement. We report here a comparative study of the colony forming capacity of trochanter and sternal or iliac crest marrow from five hematologically normal donors. Our data indicate that trochanter marrow is a reliable source of normal in vitro granulocyte/macrophage colony forming cells.

Bone Marrow Cells↗
PubMed1979

NADPH production in the oxidative pentose phosphate pathway as source of reducing equivalents in glycolysis of human red cells in vitro.

Studies have been carried out on human erythrocytes in vitro to clarify the deficit of pyruvate formation under conditions when 2,3 DPG is degraded. The results lead to the conclusion that there exist a cross connection between the glycolytic and the oxidative pentose phosphate pathway which is mediated by the NADP/NADPH couple. NADPH serves as additional reducing equivalent in the reaction of the LDH. In the absence of glucose the pool of the metabolites of the pentose phosphate pathway is able to supply glucose-6-phosphate for the production of NADPH by recombination. The reaction of NADPH at the LDH is probably of significance under in vivo conditions.

Diphosphoglyceric Acids↗
PubMed1978

Valve origin of the aortic incisura.

The occurrence and magnitude of the incisura of the central aortic pressure were shown in 66 patients to depend on the functional state of the aortic valve. In normal subjects and children with congenital aortic stenosis (with thin flexible leaflets), the incisura ranged between 6 and 14 mm Hg. With aortic regurgitation, the incisura diminished as the severity of regurgitation increased. With calcific aortic stenosis, the incisura was smaller or absent. These observations imply a valve mechanism productive of the incisura. In vitro studies of human aortic valves confirmed these observations. Additional in vitro studies with high speed cinematography (2,000 frames/sec) of a stented normal porcine valve also showed that early diastolic stretch and recoil of the leaflets occurs. These results indicate that in the presence of a normal or diseased aortic valve the aortic incisura is produced primarily by valve distension or recoil, respectively. Distension and rebound of the aortic walls do not appear to contribute significantly in the presence of a normal or a diseased valve. Because acquired aortic valve disease affects the magnitude of the central aortic incisura, inspection of the incisura may be of ancillary valve in evaluating the pathologic state of the aortic valve.

Adult↗
PubMed1976

Human insulinoma tissue: in vitro studies of proinsulin/insulin biosynthesis and release.

The rate of proinsulin/insulin turnover has been studied in human insulinoma tissue from ten patients. During the incubation of tumor tissue the ratio of immunoreactive insulin (IRI) release to content was significantly higher than that from isolated human pancreatic islets. The tumor cell cytoplasm (100,000 g supernatant S-100) contained approximately 45% of the IRI. Endogenous proinsulin and insulin were released throughout the incubation. Newly synthesized proinsulin was detected in the 15 min pulse microsomal, secretory granule, S-100 and media samples. These results suggest that defective hormonal storage and release mechanisms are operative in human insulinoma cells resulting in a higher turnover of proinsulin and insulin compared with pancreatic islet tissue.

Adenoma, Islet Cell↗
PubMed1977

The permeability of the human ciliary and iridial epithelium to horseradish peroxidase. An in vitro study.

The permeability of the human ciliary epithelium to horseradish peroxidase (PO) has been studied in vitro with the electron microscope. Ciliary body and iris specimens were obtained from freshly enucleated eyes. PO was applied at the stromal side of the epithelium, and was left for 120 min. The movement of PO through the intercellular spaces of the human ciliary epithelium was blocked apically in the lateral intercellular spaces of the non-pigmented epithelial cells, indicating that these cells are girdled by zonulae occludentes. In the iridial epithelium, the same distribution pattern of peroxidase reaction products (PORP) was found, i.e. the progression of PO was blocked apically in the lateral intercellular spaces of the posterior epithelial cells. The study indicates that the human ciliary and iridial epithelium contains a system of zonulae occludentes, which represents a diffusion barrier to high molecular, water soluble substances. This is consistent with previous studies in several species of animals.

Adult↗
PubMed1979

[In-vitro motility studies on the strips of the human gallbladder (author's transl)].

Studies in-vitro motility of the human gallbladder was investigated in the longitudinally cut strips obtained from 24 patients. Strips of the wall of the organ, containing mucosa, muscle and serosa, 5 mm in width and 15 mm in length, were cut from the fundus, body and neck. These specimens were suspended in Tyrode solution at 36 degrees C equilibrated with the 100% O2. Recordings were made on a pen chart recorder which were transduced using a isometric system by the changes of contractions. The results obtained were as follows: 1. The strips from three parts of the gallbladder showed rhythmic and tonic spontaneous contractions. 2. The tonic contractions from fundus were strongest in those three. 3. The rhythmic contractions of neck exhibited greater amplitude than those of fundus and body.

Adult↗
PubMed1977

In vitro steroid metabolic studies in human testes. II: Metabolism of cholesterol, pregnenolone, progesterone, androstenedione and testosterone by testes of an estrogen-treated man.

The effect of long-term in vivo estrogen treatment on in vitro steroidogenesis by the testes of a young man was investigated. In vitro incubation of testicular tissue of this man with 3H-pregnenolone, 3H-progesterone, 3H-androstenedione and 3H-testosterone demonstrated suppression of 17-hydroxylase activity, with little or no effect of the treatment on delta5-3beta-hydroxysteroid oxidoreductase, 5alpha-reductase and aromatase. Increased 20alpha-hydroxysteroid oxidoreductase activity was observed. Determination of intratesticular steroid concentrations led to similar conclusions.

Adult↗
PubMed1975

An in vitro method for study of human lymphocyte cytotoxicity against mumps-virus-infected target cells.

A chromium release assay was used to study lymphocyte-mediated cytotoxicity against mumps virus-infected target cells in vitro. Purified lmyphocytes from randomly selected donors killed significantly more virus-infected Vero cells than non-infected cells. Lymphocyte-target cell ratios of 50 to 100:1 and incubation period from 16 to 20 hr were optimal for determination of cytotoxicity. The lymphocyte induced chromium release was not obviously correlated with serum mumps hemagglutination-inhibition titers of the effector cell donors. However, the lymphocyte reaction against virus-infected target cells seems to have an immunologic basis. Thus, the more pronounced susceptibility of mumps-infected target cells as compared to non-infected cells was not due to a cytocidal effect of the virus, since spontaneous isotope release from both target cells was the same. Also, cord blood lymphocytes which had exhibited good cytotoxicity when induced either with phytohemagglutinin or with antiserum against target cell antigens were not cytotoxic for mumps-infected Vero cells. Moreover, the lymphocyte reaction against virus infected target cells could be inhibited by high concentrations of hyperimmune rabbit antimumps sera. On the other hand, lower concentrations of antisera specifically poteniated the lymphoycte-mediated isotope release from mumps-infected target cells.

Animals↗
PubMed1979

The kinetics of iron uptake in vitro by human duodenal mucosa: studies in normal subjects.

1. A method for determining initial rates of unidirectional radio-Fe uptake from a ferric chelate of nitrilotriacetic acid by human duodenal biopsy specimens in vitro has been devised. [57Co]cyanocobalamin was used as an extracellular fluid marker, and was shown to give results in close agreement with other markers. 2. Uptake was linear for up to 20 min and exhibited saturation kinetics over the concentration range 18--450 mumole/1. 3. In the presence of 2:4 dinitrophenol and fluoride, uptake was reduced by approxi-50%, indicating dependence on metabolic energy. 4. Uptake of Fe was markedly diminished at reduced incubation temperatures, demonstrating a high activation energy for the uptake process. 5. Many of the criteria for the demonstration that the initial uptake of Fe depends on an active transport mechanism have been fulfilled. 6. The apparent distribution volume of 14C-labelled nitrilotriacetate chelate did not exceed the extracellular fluid space, suggesting that Fe is transferred to specific receptors on the enterocyte. The findings are discussed in relation to the possibility that uptake may be a rate-controlling step for the regulation of net intestinal absorption of Fe in man.

Biological Transport, Active↗
PubMed1975

[Pentose phosphate pathway and nucleic acid synthesis in human funicular tissue. In vitro studies].

Umbilical cord slices were incubated with either 1- or 6-14C-glucose, the radioactivities of which were measured in CO2 evolved. The ratio, 1 CO2/6 CO2 was low, being comprised between 1 and 2. Furthermore, this incubation of cord slices with tritiated uridine or thymidine resulted in very low incorporations, especially for the latter. Therefore, both the pentose phosphate pathway and the synthesis of nucleic acid have a low activity in the cord tissue: these might be signs of senescence in this otherwise fetal organ.

Carbon Dioxide↗
PubMed1975

[Chemotaxis of human polymorphonuclear cells in vitro. Study of inflammatory rheumatic diseases].

Sixty-eight determinations of leukocyte chemotaxis were performed in 42 patients suffering from systemic lupus erythematodes (17 cases), rheumatoid arthritis (15 cases) and scleroderma (10 cases). In contrast to the results of others, this study showed a deficiency in only 15 of 42 cases (35.7%). Impairment of chemotaxis was always transitory and demonstrable only during acute phases of disease. Intrinsic deficiency of PMN leukocytes as well as deficiency of plasma factors were related to the clinical and biological course of the disease and to the treatment.

Antibodies, Antinuclear↗
PubMed1979

Amikacin: in vitro bacteriological studies, levels in human serum, lung and heart tissue, and clinical results.

The amikacin sensitivity of bacteria cultured from 3282 clinical cases of mixed type was determined. Gentamicin and amikacin were equally effective against E. coli strains. Amikacin inhibited the growth of more Pseudomonas aeruginosa strains than did gentamicin. Against Gram-positive bacteria gentamicin proved to be more effective. Many of the gentamicin-resistant strains were sensitive to amikacin. Amikacin levels were measured during 21 pulmonary and 14 heart operations, subsequent to a intramuscular administration of 500 mg amikacin. The serum contained 17-20 microgram/ml amikacin, in the intact, inflamed and tumourous parts of removed lung tissue 9, 6 and 6 microgram/g concentrations were detected, respectively, whereas the cardiac auricle and the pericardial fluid contained 3-4 and 2-4 microgram/ml, respectively. These amikacin levels reach or in most cases even exceed the minimal inhibiting concentrations against the bacteria. Therefore, amikacin is excellent for the treatment of respiratory infections, pericarditis and endocarditis caused by Gram-negative, gentamicin-resistant bacteria. Amikacin treatment of 8 patients with grave diseases as well as the successful local administration of amikacin based on the therapy of 55 cases of surgical suppurations is reported.

Amikacin↗