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Biomedical subjects

P Herman

Publications and source records attributed to P Herman.

At least 127 records · Page 7Linked to original sources
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↗
PubMed1983

Organicity and mental retardation: organic mental syndrome battery.

Fifteen mentally retarded children were tested and compared to 10 normal school children. They were administered a battery of tests reflecting organic brain disease, consisting of the Face-Hand, Midline Crossing and Independent Eye Movements Tests. Normals performed correctly 98% of the time on the three combined tests, while the mentally retarded scored only 34% correct. There was a significant correlation between IQ and this battery of tests (the 'OMSB'). When the IQ and OMSB were conflicting, a repeat of the former indicated that the IQ value was erroneous. The OMSB may be useful along with IQ testing as a rapid screening method to evaluate the presence of organicity and its severity.

Adolescent↗
PubMed1981

Organicity and mental retardation: analysis of eye and head movements.

Eye and head movements of ten mentally retarded (MR) children and ten normal school children were recorded. Each was directed to look to one side or the other in response to verbal commands, to gestural directions, or to the appearance of illuminated fixation targets. Under these conditions: 1. Large gaze movements of MR subjects were accompanied by head movements more frequently than those of the normal subjects. Furthermore, for similar gaze deviations, head movement of MR subjects tended to be larger than those of normal subjects. 2. Head movements of normal subjects rarely began before eye movement, but those of MR subjects often did so. This "abnormal" MR eye-head movement pattern was more frequent in response to verbal or gestural commands than in response elicited by illumination of fixation targets.

Child↗
PubMed1977

Role of ecdysone, pupariation factors, and cyclic AMP in formation and tanning of the puparium of the fleshfly Sarcophaga bullata.

Two pupariation factors, anterior retraction factor (ARF) and puparium tanning factor (PTF), are absent from the hemolymph of larvae at the time of tanning accelerated by ARF/PTF, cyclic AMP, or dopamine. ARF and PTF are not involved in derepression of dopa decarboxylase (aromatic L-amino-acid decarboxylase, aromatic L-amino-acid carboxy-lyase, EC 4.1.1.28) synthesis initiated by ecdysone. Tanning is entirely inhibited by injection of two transcriptional inhibitors, actinomycin and BrdUrd, and two translational inhibitors, puromycin and cycloheximide. Retraction activity is more severely inhibited by the transcriptional than by the translational inhibitors. A tanning response is initiated by cyclic AMP in the presence of the transcriptional but not the translational inhibitors. Dihydric tanning substances (dopa, dopamine) initiate tanning in the presence of both types of inhibitors. Release of ARF and PTF from the central nervous system is inhibited by the four inhibitors. ARF totally reverses the inhibitory effects on retraction, whereas PTF does not reverse inhibition of tanning. These data are interpreted to mean that PTF is concerned with the regulation of two components of the tanning response: (i) acceleration of synthesis of a particular protein (associated with the tyrosine hydroxylation complex), and (ii) activation via cyclic AMP of a component of the tyrosine hydroxylating system.

Journal Article↗
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

Direct intratumoral embolization of juvenile angiofibroma.

INTRODUCTION: Embolization is a well-established technique that facilitates the subsequent surgical removal of vascularized tumors such as juvenile angiofibroma. However, there is risk of a neurological accident during angiography and tumor embolization from the internal carotid artery. Direct intratumoral embolization may help prevent these potential side effects. METHOD: A group of 7 patients with juvenile angiofibroma vascularized through the branches of the internal carotid artery underwent direct tumoral embolization under general anesthesia. An injection made slowly with an intranasal or lateral percutaneous route with either a mixture of cyanoacrylate, lipiodal, and tungsten powder. Continuous radiographic control was used. RESULTS: This technique induced a marked devascularization and necrosis of the tumor. The technique provided useful perioperative visualization of the tumor. No neurologic sequelae were encountered. CONCLUSION: Direct intratumoral embolization deserves further consideration. This might be especially important in tumors with extracranial extension, cavernous sinus involvement, or those with small or multiple recurrences.

Adolescent↗
PubMedDate not supplied

Pathophysiology of middle ear epithelium: a new role for prostaglandin E2.

INTRODUCTION: Otitis media with effusion is a disease of the middle ear epithelium resulting from a decreased sol layer as well as increased mucus secretion and plasma-derived protein transudation, which causes mucus plugging. Because the epithelium keeps the middle ear cavities fluid-free and air-filled, we investigated its fluid transport capacities, which may be involved in both efficacy of the mucociliary clearance and drying-out of the posterior ear cavities (Yen PT et al: Acta Otolaryngol (Stockh) 113, 1993). We have established the absorptive capacity of middle ear epithelial cells in primary culture (Herman P, et al: Am J Physiol 262, 1992). However, the paucity of cells obtained by enzymatic digestion led us to develop a new model for further investigation of middle ear epithelial cell. METHODS: We established a middle ear cell line (MESV) using simian virus 40 (SV40) infection of middle ear epithelial cells from the Mongolian gerbil. RESULTS: Investigation of the transport processes using the short-circuit current technique showed that MESV cells retain most characteristics of the original middle ear epithelial cells. Transepithelial sodium transport from the apical to the basal side was responsible for the transepithelial lumen-negative potential difference. CONCLUSION: The presence of high concentrations of prostaglandin E2 in the middle ear effusions has been documented. This work investigates the effect of prostaglandin E2 on the rate of transepithelial ion transport of MESV cells. Prostaglandin E2 increased the rate of electrogenic sodium transport by means of increase in the intracellular cyclic adenosine monophosphate (cAMP) content. Such a modulation of sodium transport in the course of otitis media could be responsible for the reduced periciliary sol layer that impairs the mucociliary clearance.

Animals↗
PubMedDate not supplied

Extracellular ATP modulates ion transport via P2Y purinoceptors in a middle-ear epithelial cell line.

Mucus and cellular debris are eliminated from the middle-ear cavity through the E-tube by the mucociliary system. Depth of the periciliary fluid layer is thought to be regulated by epithelial ion transport activity. Since impairment of the mucociliary system is a key step in the development of otitis media with effusion, we investigated the ion transport mechanisms of the middle-ear epithelium using the middle-ear MESV cell line. ATP has been shown to modulate ion transport as well as various cellular functions in several cell types via purinoceptors. In order to investigate a possible modulation of the transport activity of MESV cells, we evaluated short-circuit current (Isc) changes in response to specific stimulation of putative purinoceptors by ATP and its various analogs. ATP dramatically increased Isc, while adenosine had no effect, thus demonstrating the presence of P2 receptors according to the original classification by Burnstock. The rank order of potency of purinoceptor agonists for stimulation of Isc on the apical side (ATP > UTP > gamma-SATP >> beta-SADP > 2-methylthio-ATP, 2MeSATP > beta, gamma-methylene-ATP, beta,gamma-MeATP) and on the basolateral side (ATP > gamma-SATP > UTP >> beta-SADP > 2 MeSATP > beta,gamma-MeATP), along with studies using selective antagonists and intracellular calcium measurements are consistent with a P2Y receptor subtype. The ATP-induced increase in Isc was related to sodium transport. This modulation might be of importance in stress conditions such as inflammation.

Adenosine Triphosphate↗