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P Herman

Publications and source records attributed to P Herman.

15 recordsLinked to original sources
PubMed1992

Ion transport by primary cultures of Mongolian gerbil middle ear epithelium.

The transport properties of Mongolian gerbil middle ear epithelial cells grown in primary culture were studied. These cells formed polarized monolayers that exhibited domes on nonporous supports. On porous supports, monolayers developed an apical-negative transepithelial electric potential difference (VT = -37.2 +/- 2.7 mV) and a transepithelial resistance (RT = 519 +/- 56 omega.cm2). The short-circuit current equivalent (Ieq) was 62.4 +/- 6.2 microA/cm2 (mean +/- SE, n = 15). Na+ and Cl- accumulated in the basal bath and generated a basolateral hyperosmolarity that drove a net water flow. Amiloride (10 microM), when added to the apical but not to the basal bath, induced a 23.4 +/- 1.5 mV and 44.1 +/- 1.3 microA/cm2 decrease of VT and Ieq, respectively, while RT increased by 403 +/- 69 omega.cm2 (P less than 0.001, n = 15). Exposure of the monolayers to a low-Cl- solution (30 mM) enhanced the transepithelial potential, possibly by means of a Cl- secretion through apical Cl- channels. Isoproterenol (10(-4) M basolateral) increased intracellular adenosine 3',5'-cyclic monophosphate (cAMP) content (concentration of half-maximal response = 2.5 x 10(-7) M) and decreased VT, RT, and Ieq. The isoproterenol-induced fall of VT occurred even in the presence of low-Cl-solutions. This suggested an increase of the paracellular pathway conductance, although there was no significant modification of the mannitol permeability.(ABSTRACT TRUNCATED AT 250 WORDS)

Amiloride↗
PubMed1992

c-myc antisense oligonucleotides inhibit the colony-forming capacity of Colo 320 colonic carcinoma cells.

Colo 320 cells are colonic carcinoma cells known to express abundant c-myc mRNA. Based on the response of several hematopoietic cell lines to chemical inducers of differentiation, we reasoned that such agents might have similar inductive activity in Colo 320 cells. Accordingly, we exposed Colo 320 cells to 5 mM sodium butyrate (NaBT) for 7 d. C-myc expression decreased threefold and self-replicative potential decreased (defined as a greater than 60% decrease in colony-forming capacity in soft agar that did not contain inducer). In an effort to demonstrate a direct cause and effect between myc expression and the colony-forming capacity of Colo 320 cells, we exposed these cells to a 15-base antisense c-myc oligonucleotide (complementary to the translation initiation region of exon II). Cells were also exposed to equimolar (20 microM) amounts of sense and missense oligonucleotides. Subsequently, cells were incubated at 10, 20, 30, and 40 microM antisense DNA for 16 h, then washed and plated in oligonucleotide-free agar medium. We demonstrated that: (a) the oligomers were stable in the extracellular medium and in the cell cytoplasm; (b) the uptake of the oligonucleotides was 0.7%; (c) sense and missense oligonucleotides had no effect on colony-forming capacity; and (d) the antisense c-myc oligonucleotide resulted in a 40-75% concentration-dependent decrease in colony-forming capacity. The specific inhibition of colony-forming capacity by antisense DNA suggests that the role of myc expression in Colo 320 cells is similar to its role in hematopoiesis, and that the failure to inhibit myc expression maintains colony-forming capacity. This system provides a new strategy for inducing differentiation and may provide further insight into the genetic factors that govern the process of colonic carcinogenesis.

Butyrates↗
PubMed1991

A new method of measuring dimensional change.

A new method of measuring linear dimensional change in denture base resins is presented and its precision in determining distances between two points was investigated. Chrome steel ball bearings 1.57 mm in diameter were invested in a stone mold and were used to record measurements by a reflection from the surface of the ball bearings. The accuracy of this method was determined by performing repeated measurements between two points in a stone mold. Random measurements were made to an accuracy of 0.002 mm. The dimensional change of light-cured, heat-cured, and self-cured denture base resins was also determined with this method, followed by an analysis of variance of the data. The findings support the accuracy and reproducibility of this new method in recording linear measurements. The dimensional changes of all three resins were different from each other after the specimens were processed and stored in distilled water for 7 days at 37 degrees C.

Acrylic Resins↗
PubMed1991

A model for cell-type determination and differentiation in plants.

We are using trichome formation on the plant Arabidopsis thaliana as a model for the study of plant cell determination and differentiation. Several of the genes that are required for trichome formation are defined by mutations. Two mutations, ttg and gl1, prevent the initiation of trichome differentiation. Thus, these mutations define products that are involved in the signalling of trichome determination. Other mutations, gl2, gl3, dis1, and dis2, define genes that are involved in trichome maturation. Our immediate goal has been to isolate the genes defined by these mutations and determine the role that they play in trichome formation. Our general goals are (1) to identify counterparts to these genes that are involved in other cell type determination and differentiation processes; (2) to manipulate cell development by altering the normal expression of these genes; and (3) to determine if this information can be used to improve crop plants. Presently, most of our progress has centered on the GL1 gene, which has been isolated and characterized. We have found that GL1 is a myb-related gene that is uniquely required for trichome initiation. As in other plants, Arabidopsis has a family of myb-related genes. We are currently investigating the possibility that some of these other myb-related genes are also uniquely required for other types of cell determination events.

Arabidopsis↗
PubMed1991

[Culture of the epithelium of middle ear in the study of seromucous otitis].

Preliminary results on transport properties of middle ear epithelium in primary culture are reported. Primary cultures of Mongolian gerbil (Meriones unguiculatus) middle ear epithelial cells were undergone. These cells formed polarized monolayers that exhibited domes when grown to confluence on non porous support. Domes are the consequence of active transepithelial transports of solutes and water. On porous support, Na+ and Cl- accumulated in the basal bath and generated a basolateral hyperosmolarity that drove a net water flow. This solutes and water absorption was the consequence of an active Na+ transcellular transport, by means of apical sodium channels, that was responsible for the transepithelial potential difference, lumen negative: -39 +/- 1.2 mV (mean +/- SEM, n = 63). Transport of fluid and ions in the middle ear cavities could play a major role in keeping the cavities fluid-free and air-filled and modulating the mucociliary clearance. Modulation of these transports could be involved at the start of otitis media with effusion, and would contribute to the mucociliary clearance impairment.

Absorption↗
PubMed1990

Transmembrane potential measurement with carbocyanine dye diS-C3-(5): fast fluorescence decay studies.

The mechanism of carbocyanine dye diS-C3-(5) fluorescence intensity variations with transmembrane potential changes has been studied using time-resolved fluorescence spectroscopy. Clear evidence is given of the transmembrane-potential-dependent partition of the dye among various sites with different fluorescence lifetimes. It was found that fluorescence decay profiles reflect the transmembrane potential changes.

Benzothiazoles↗
PubMed1977

3':5'-cyclic AMP and hormonal control of puparium formation in the fleshfly Sarcophaga bullata.

Injection of 3':5'-cyclic AMP (cAMP) into larvae of the fly Sarcophaga bullata 3-4 hr before the beginning of puparium formation (red-spiracle stage) greatly accelerates the onset of tanning without affecting initiation of puparium formation (anterior retraction). Accelerated tanning resembles real tanning in two important respects: the solubility of cuticular proteins becomes reduced and [U-14C]tyrosine is incorporated into the cuticle. Of a number of cAMP analogues tested, 3':5'- cyclic GMP, 2':3'-cyclic AMP, and 5'-AMP were inactive, dibutyryl-3':5'-cAMP had only slight activity, and cyclic IMP and deoxy-3':5'-cAMP showed some activity. Theophylline enhanced the effect of small doses of cAMP or of blood, diluted 1:8, active in the puparium tanning factor. Injection of dopa, dopamine, acetyldopamine, or epinephrine, but not of tyrosine, had an accelerating effect similar to that of cAMP. The tanning-inhibiting effect of DL-alpha-methyl-alpha-hydrazino-beta-(3,4-dihydroxyphenyl)propionic acid monohydrate is reversed by dopamine or epinephrine, but not by tyrosine, dopa, or cAMP. Evidence is presented to indicate that the responses to cAMP are not artifacts but reflect actual biochemical events during tanning.

Animals↗
PubMed1976

A modification of eye-head coordination by CNS disease.

When a subject, seated and facing ahead, was asked to look toward one side, the result was a combined movement of the eyes and head. Normal subjects began the eye movement just before the onset of head movement; 4 neurologic patients who showed abnormalities in eye movements (saccades that tended to be smaller in amplitude and lower in velocity than those of the control subjects) regularly began eye movement after the onset of head movement. Thus the initiation of the head rotation was not as much retarded in these patients as that of eye movement. Amplitudes of the movements were reduced in the patients, but this change too was less for the head than for the eyes. Because the amplitude and velocity of the head movement were less affected in the patient group, the relative contribution of the head to the total gaze shift was increased. It appears as if, when the oculomotor system is affected, the head can assume a leading role in the initiation and execution of gaze shifts.

Eye Movements↗
PubMedDate not supplied

The Behr pupil revisited. Anisocoria following cerebrovascular accidents.

Three hundred and sixty-three cases of cerebral infarction were reviewed: 19 had anisocoria. Eighty percent had the larger pupil contralateral to the hemispheric lesion. The mydriasis was associated with long tract signs in all instances. If the abnormal pupil and long tract signs are not on the same side, the long tract signs are the most accurate evidence of the side of thhe hemispheric lesions. When the pupil was 4 mm or larger and reacted sluggishly, the prognosis was poor. The mechanism of the production of the anisocoria is still uncertain; the lesion is probably "cortical" and in the contralateral hemisphere.

Cerebrovascular Disorders↗
PubMedDate not supplied

[Differential diagnosis of cholestasis in pancreatic cancer and chronic pancreatitis].

The clinical, biochemical and radiological data of 25 patients with carcinoma of the head of the pancreas were compared with the same parameters of 25 patients with chronic pancreatitis producing cholestasis. History of alcohol abuse, pruritus and palpable gallbladder were the only clinical findings useful for the differential diagnosis. Plasma bilirubin levels were significantly higher in patients with malignancy (20.0 +/- 14.3 vs 2.5 +/- 2.4) but the course of the bilirubinemia was similar in the two groups after hospital admission. Preoperative ultrasound and cholangiography were usefull in differentiating both groups of patients. Sensibility of a point score based on significant differences was 100% for pancreatitis and 96% for malignancy.

Adult↗
PubMedDate not supplied

[Leiomyosarcoma of the inferior vena cava: report of a case].

Leiomyosarcoma of the inferior vena cava is a rare tumor. The authors report a case and discuss the clinical features, diagnosis and treatment of this disease. With recent advances in radiologic and surgical procedures an early diagnosis and radical resection might be possible, leading to a better prognosis or even to the cure of the condition.

Adult↗
PubMedDate not supplied

[Splenic abscess: report of 8 cases and review of the literature].

Eight patients with splenic abscess are reported. Etiological factors were sepsis, mainly due to endocarditis. Diagnosis was made by ultrasonography and computed tomography scans. Splenectomy was performed in four cases, transcutaneous drainage in three and abscess puncture in one case. Mortality was 12.5% (1/8). Since the introduction of US and CT scans early diagnosis and treatment was possible by which the mortality decreased.

Abscess↗
PubMedDate not supplied

Convergence spasm.

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Adult↗