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Biomedical subjects

J Muller

Publications and source records attributed to J Muller.

At least 181 records · Page 10Linked to original sources
PubMed1984

Aggregate-carrying membranes during ADH stimulation and washout in toad bladder.

Aggregates of intramembrane particles are found in cytoplasmic structures that we now term "aggrephores." Antidiuretic hormone (ADH) causes aggrephores to fuse with the luminal membrane. Aggregates subsequently become dispersed in the membrane and behave as sites for water flow. In the present studies we examined further the behavior of aggrephores. 1) Bladders stimulated for 10, 30, or 60 min in the absence of an osmotic gradient had two to three times more fusions as those stimulated in the presence of a gradient, indicating that aggrephore fusion frequency is influenced by water flow. 2) ADH stimulation did not change the projected luminal surface area of granular cells. Thus fused aggrephores remain fixed while aggregates move from the aggrephore to flat areas of luminal membrane. 3) Horseradish peroxidase, present in the mucosal baths of bladders stimulated with and then washed of ADH, was found in the lumen of cytoplasmic aggrephores; aggrephores therefore detach from the luminal membrane during washout. The same bladders had about twice as many multivesicular body-type lysosomes as unstimulated bladders, suggesting that, after detachment, aggrephores may join or become lysosomes. 4) Colchicine did not affect the rate of disappearance of fusion sites during washout, whereas cytochalasin B slowed it, suggesting that aggrephore detachment depends of microfilaments, but not microtubules.

Animals↗
PubMed1984

Interleukin 2 production induced by chemically defined cell membrane modification.

We present evidence that murine spleen cells produce a T-cell growth-stimulating factor following oxidation by periodic acid (H5IO6). The identification of this factor as interleukin 2 (IL-2) is indicated by its ability to support the growth of the IL-2-dependent CT6 cell line. In addition, preliminary analysis shows that H5IO6-stimulated growth factor has biochemical properties similar to IL-2. The time course of H5IO6-induced IL-2-like production by spleen cells was determined. No growth-stimulating activity was detected after 1 h of culture. The peak of periodic acid-induced IL-2-like production was between 18 and 24 h, while the maximum 3H-thymidine incorporation in spleen cells occurred at 72 h. Flow cytometry of CT6 cells was used for cell cycle analysis and to demonstrate their stimulation by IL-2-containing supernatants. These results were in agreement with the 3H-thymidine incorporation data. Electron microscopy of CT6 cells stimulated by supernatants from concanavalin A- or H5IO6-treated spleen cells showed no differences in their morphology. Degradation of spleen cell sialic acid prior to periodic acid oxidation inhibited IL-2-like production by 84% and inhibited 3H-thymidine uptake by 80%.

Animals↗
PubMed1984

Multiple fusiform intracranial aneurysms following curative radiation therapy for suprasellar germinoma. Case report.

A 17-year-old girl died from the rupture of a large fusiform aneurysm of the terminal internal carotid artery. Autopsy revealed three other fusiform aneurysms originating from major cerebral arteries clearly within the ports of previously administered telecobalt radiation therapy. Five years prior to her death, a suprasellar germinoma was partially removed and the area was treated by radiation therapy via three ports. The original arteriograms showed a normal vascular tree. Repeat arteriograms, 3 years and 8 months before her death, demonstrated the aneurysms. The development of aneurysms following radiation damage of the arteries has been reported previously, but not in intracranial vessels.

Adolescent↗
PubMed1983

Concentration-dependent behavioral changes in mice following short-term inhalation exposure to various industrial solvents.

Mice were exposed during a 4-hr period to various concentrations of 13 aliphatic or aromatic solvents which affect primarily the central nervous system (CNS). The test compounds were benzyl chloride, butyl alcohol, chlorobenzene, cyclohexanone, 1,2-dichloroethylene, diisobutyl ketone, isopropyl acetate, methyl ethyl ketone, styrene, tetrachloroethylene, 1,1,1-trichloroethane, toluene, and ortho-xylene. After exposure, measurements were made to see whether these neurotoxicants would decrease the immobility developed in a "behavioral despair" swimming test. Each chemical was shown to reduce the total duration of immobility measured over a 3-min period in a concentration-related manner. The systematic determination of the atmospheric concentrations responsible for a 50% decrease in immobility (ID50) permitted classification of the solvents in terms of their relative potencies. The possibility of using such experimental data as tentative guidelines for setting safe levels of work exposure to the neurotoxicants was suggested, considering the existence of quantitative relationships between the ID50 values and the current occupational standards.

Animals↗
PubMed1983

Medulloblastoma (?) with epithelioid features.

A midline cerebellar tumor in an 18-year-old male, on light microscopy composed of closely packed, small featureless cells with little cytoplasm, under electron microscopic examination showed distinct epithelial features. The cells were closely apposed and joined by zonula adherentes, puncta adherentia and classical desmosomes. The latter structure has not been described in unequivocal glial or neuronal tumors or in normal cells derived from the neural tube in vertebrates, not even in ontogenesis. In many areas the tumor cells abut on extensive basement membranes. Although the majority of the cells were undifferentiated, we occasionally observed elements containing dense core vesicles, microtubules and cilia. In addition, typical astrocytes were identified. The presence of these features strongly favors the neuroectodermal origin of this neoplasm.

Adolescent↗
PubMed1983

Long-acting contraceptive agents: esters of norethisterone with alpha- and/or beta-chain branching.

The synthesis of eighteen esters of norethisterone (17 alpha-ethynyl-17 beta-hydroxyestr-4-en-3-one) is described. These all possess some form of alpha- and/or beta-substitution in the ester side-chain. The work was undertaken in order to evaluate any long-acting fertility control effect intrinsic in such compounds. A pentamethyl disiloxy ether was also included in the group of substances prepared for testing because of its similar substitution pattern.

Esters↗
PubMed1983

Cytomegalovirus encephalitis in acquired immunodeficiency syndrome.

A 38-year-old black man died from acquired immunodeficiency syndrome (AIDS) after a 15-month course. The autopsy revealed a pancolitis and a pneumonia caused by cytomegalovirus (CMV). Exceptionally, there also was a periventricular encephalitis caused by the same organism. Identification of the virus was aided by immunoperoxidase methods.

Acquired Immunodeficiency Syndrome↗
PubMed1982

Invasive orbital pseudotumor--CT demonstration of extension beyond orbit.

Two cases of orbital pseudotumor are described with computed tomographic (CT) studies showing extension of the pseudotumor beyond the confines of the bony orbit. In one patient with orbital pseudotumor involving the medial rectus muscle, the pseudotumor extended through the medial wall of the orbit into the ethmoid sinus. A second patient had extension of orbital pseudotumor into the infraorbital fissure causing enlargement of the infraorbital fissure and foramen. Both lesions were confirmed by biopsy.

Adult↗
PubMed1982

Evidence that hospital care for acute myocardial infarction has not contributed to the decline in coronary mortality between 1973-1974 and 1978-1979.

To investigate whether the reported 17% decline in the national rates of acute ischemic heart disease mortality between 1973 and 1978 was attributable to decreased in-hospital mortality for patients with acute myocardial infarction (MI), we surveyed all 63 acute care hospitals in the Boston, Massachusetts, area. Compared with 1973-1974, more 1978-1979 MI patients were admitted to hospitals in metropolitan Boston, and especially to the five university teaching hospitals. Between 1973-1974 and 1978-1979, hospital admission rates decreased for younger patients and increased for older patients, but overall admission rates were almost identical. In-hospital mortality rates from acute MI did not change significantly in any age group. Because overall MI mortality was declining while in-hospital MI mortality was unchanged, the proportion of acute MI deaths that occurred inside the hospital increased from about 30% to about 40%. Although current hospital care undoubtedly benefits many individual patients, this study suggests that improvements in the in-hospital care of acute MI patients are a major explanation for nationwide mortality trends between 1973 and 1978.

Adult↗
PubMed1982

Neurologic effects of subarachnoid administration of 2-chloroprocaine-CE, bupivacaine, and low pH normal saline in dogs.

The purpose of this study was to evaluate the neurologic consequences of deliberate subarachnoid injection of large volumes of 2-chloroprocaine-CE in experimental animals. The possible role of low pH as well as total volume as potential factors in causing neurotoxicity was evaluated. The 65 dogs in the study received injections in the subarachnoid space as follows: 6 to 8 ml of bupivacaine (N = 15), 2-chloroprocaine-CE (N = 20), low pH normal saline (pH 3.0) (N = 20), or normal saline (N = 10). Of the 20 animals that received subarachnoid injection of 2-chloroprocaine-CE seven (35%) developed hind-limb paralysis. None of the animals that received bupivacaine, normal saline, or normal saline titrated to a pH 3.0 developed hind-limb paralysis. Of the 15 spinal cords of the animals that received 2-chloroprocaine-CE, 13 showed subpial necrosis; the nerve roots and subarachnoid vessels were normal. The spinal cords of the animals that received bupivacaine, low pH normal saline (pH 3.0), or normal saline did not show abnormal findings.

Anesthesia, Epidural↗
PubMed1981

Fluorocarbons reduce myocardial ischemic damage after coronary occlusion.

Open-chest, anesthetized dogs with occlusions of the left anterior descending coronary artery breathed 100 percent oxygen while they were bled to a hematocrit of 25 percent and infused with an approximately equal volume (40 milliliters per kilogram) of fluorocarbon preparation or Ringer solution. Dogs breathing room air and receiving no treatment served as controls. After undergoing 6 hours of coronary occlusion, animals bled and treated with fluorocarbons developed smaller infarctions than those receiving Ringer solution or no treatment.

Animals↗
PubMed1981

Stabilization of vasopressin-induced membrane events by bifunctional imidoesters.

Vasopressin increases the water permeability of the luminal membrane of the toad bladder epithelial cell. This change in permeability correlates with the occurrence in luminal membranes of intramembrane particle aggregates, which may be the sites for transmembrane water flow. Withdrawal of vasopressin is ordinarily associated with a rapid reduction of water flow to baseline values and a simultaneous disappearance of the particle aggregates. The bifunctional imidoesters dithiobispropionimidate (DTBP) and dimethylsuberimidate (DMS), which cross-link amino groups in membrane proteins and lipids, slow the return of water flow to baseline after vasopressin withdrawal. Cross-linking is maximal at pH 10, and is reduced as pH is lowered. Freeze-fracture studies show persistence of luminal membrane particle aggregates in cross-linked bladders and a reduction in their frequency as water flow diminishes. Fusion of aggregate-containing cytoplasmic tubular membrane structures with the luminal membrane is also maintained by the imidoesters. Reductive cleavage of the central S-S bond of DTBP by beta-mercaptoethanol reverses cross-linking, permitting resumption of the rapid disappearance of the vasopressin effect. Bladders that have undergone DTBP cross-linking and beta-mercaptoethanol reduction respond to a second stimulation by vasopressin. Thus, the imidoesters provide a physiologic and reversible means of stabilizing normally rapid membrane events.

Animals↗
PubMed1981

Role of osmotic forces in exocytosis: studies of ADH-induced fusion in toad urinary bladder.

Antidiuretic hormone (ADH) treatment of toad urinary bladder activates an exocytotic-like process by which intramembrane particle aggregates are transferred from membranes of elongated cytoplasmic tubules to the luminal-facing plasma membrane. We find that the number of these ADH-induced fusion events, and the number of aggregates appearing in the luminal membrane, are reduced when the luminal bathing medium is made hyperosmotic. As an apparent consequence of the inhibition of their fusion with the luminal membrane, the elongated cytoplasmic tubules become enormously swollen into large, rounded vesicles. These results are consistent with the view that osmotic forces are essential to the basic mechanism of exocytosis.

Animals↗