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Biomedical subjects

J Helman

Publications and source records attributed to J Helman.

At least 19 recordsLinked to original sources
PubMed2001

Occult maxillofacial trauma in epilepsy.

Epilepsy is a relatively common neurological disorder with incidence in both developed and developing countries. Head, facial, and oral injuries can result from seizures experienced by the epileptic patient. Patients with severe epilepsy often experience other dental disease due to their inability to properly maintain their oral hygiene. This paper presents a case of a chronic mandibular fracture following an episode of seizures in a patient with epilepsy in whom the fracture was discovered when he developed a fistula in the submandibular region.

Chronic Disease↗
PubMed1993

Low lead level in teeth in Israel.

A total of 180 sound teeth extracted from people living mainly in Northern Israel and some in the center of the country, aged 14-75 years, were analysed by graphite furnace atomic absorption spectrophotometer. The average lead level in teeth roots ranged between 1.61-25.72 micrograms/g dry root, according to the donor's age. This low level was measured in all the regions which were checked, with no significant differences between them, despite differences in levels of motor traffic rates. Based on the low lead level in teeth, we assume that no further reduction in the lead level in gasoline is needed, as long as motorization rate or gasoline consumption does not change significantly.

Adolescent↗
PubMed1989

Treatment of mandibular fractures by means of compression osteosynthesis.

This report is a retrospective study of 76 patients with mandibular fractures treated by compression osteosynthesis. Good results were achieved in 83% of the cases. The complications encountered were either soft tissue infections or minor malocclusions. It was concluded that the relatively low rate of complications can be further reduced by careful selection of patients and meticulous performance of the technique.

Adolescent↗
PubMed1988

Bowstringing as a complication of trigger finger release.

Bowstringing is a rare complication of trigger finger release caused by excessive loss of the proximal pulleys. As the flexor tendon moves away from the center of rotation of the metacarpophalangeal joint, the flexion moment arm is increased. Thus the flexors gain an increased mechanical advantage over the extensors resulting in limited digital extension. We describe a case of severe bowstringing progressing over 9 years resulting in pain, altered digital function, and loss of full extension.

Adult↗
PubMed1987

Adrenoreceptor mobilization of calcium in rat submandibular cells.

The stimulation of adrenoreceptors by epinephrine leads to an alteration in the Ca2+ homeostasis of rat submandibular cells. The relative contributions of alpha- and beta-adrenoreceptors were assessed with specific adrenergic agents. Stimulation of alpha 1-adrenoreceptors resulted in enhanced unidirectional 45Ca2+ fluxes, while such effects following beta-adrenoreceptor stimulation, though suggestive, were equivocal. When the cytosolic Ca2+ level was followed in cells pre-loaded with the Ca2+-sensitive fluorescent indicator Quin 2, clear results were observed. Both alpha 1- and beta-adrenoreceptor stimulation were capable of mobilizing intracellular and extracellular Ca2+ pools, as assessed by differential responses of cells incubated in media (+/-)-ethylene-glycol-bis-(beta-aminoethyl ether)-N,N'-tetraacetic acid. However, Ca2+ mobilization following alpha 1-adrenoreceptor stimulation was more rapid (initial rate approximately 4-5 X) and to a greater extent (approximately 2 X) than seen with beta-adrenoreceptor stimulation.

Animals↗
PubMed1987

Inhibition of alpha 1-adrenergic responsiveness in intact cells by a new, irreversible receptor antagonist.

A novel alpha 1-adrenoreceptor antagonist, 1-(4-amino-6,7-dimethoxy-2-quinazolinyl)-4-(2-bicyclo [2.2.2] octa-2,5-dienylcarbonyl) piperazine, was synthesized and shown to potently block alpha 1-adrenoceptor-induced Ca2+ mobilization in intact rat parotid acinar cells. Irreversible inhibition was complete in less than 5 min. This alkylating prazosin derivative blocked Ca2+ release (IC50 approximately 5 X 10(-10)M) and [3H]-prazosin membrane binding (IC50 approximately 3 X 10(-10)M) in a concentration dependent fashion and increased the EC50 of epinephrine for Ca2+ efflux by approximately 35 fold. The agent however had no effect on muscarinic receptor-induced Ca2+ mobilization, or beta-adrenoreceptor-induced protein secretion, from cells. These findings suggest that this irreversible alpha 1-adrenoreceptor antagonist will be a valuable tool in probing alpha 1-adrenoreceptor function and metabolism in intact cells.

Adrenergic alpha-Antagonists↗
PubMed1987

99mTc-pertechnetate uptake in parotid acinar cells by the Na+/K+/Cl- co-transport system.

99mTc-Pertechnetate (99mTcO4-) has widespread clinical use in the diagnosis and evaluation of dysfunctions in many different tissues. However, despite the broad clinical application of this radionuclide, very little is known about the mechanism by which 99mTcO4- enters a cell. We report evidence here that 99mTcO4- shares the Na+/K+/Cl- co-transport system localized to the basolateral membrane of rat parotid acinar cells. 99mTcO4- uptake by these cells was quite rapid (t1/2 approximately 30 s), was completely inhibited by the loop diuretics furosemide and bumetanide, and was markedly dependent on the presence of Na+, K+, and Cl- in the extracellular medium. Relative to uptake measured in the presence of physiological extracellular salt concentrations (Hanks' salts), 99mTcO4- uptake was inhibited 80% by sodium replacement and 50% by potassium replacement. When Cl- was replaced with the physiologically inert anion gluconate a threefold stimulation in 99mTcO4- uptake resulted. These observations provide strong evidence that 99mTcO4- can substitute for Cl- as a substrate for the Na+/K+/Cl- co-transporter and indicate that 99mTcO4- uptake by salivary glands (e.g., as seen with salivary scintiscans), and possibly by a variety of other tissues, reflects the functional activity of this co-transport mechanism.

Animals↗
PubMed1986

ATP-dependent calcium transport in rat parotid basolateral membrane vesicles. Modulation by agents which elevate cyclic AMP.

ATP-dependent Ca2+ transport was studied in basolateral membrane vesicles prepared from rat parotid gland slices incubated without or with agents which increase cyclic AMP. Isoproterenol (10(-5) M), forskolin (2 X 10(-6) M) and 8-bromocyclic AMP (2 X 10(-3) M) all increased ATP-dependent 45Ca2+ uptake 1.5- to 3-fold. The effect of isoproterenol was concentration-dependent and blocked by the beta-adrenergic antagonist propranolol. Enhanced uptake did not appear an artifact of vesicle preparation as apparent vesicle sidedness, 45Ca2+ efflux rates, specific activity of marker enzymes and equilibrium Ca2+ content were identical in vesicle preparations from control and 8-bromocyclic AMP-treated slices. Kinetic studies showed the ATP-dependent Ca2+ transport system in vesicles from 8-bromocyclic AMP-treated slices displayed a approximately 50% increase in Vmax and in Km Ca2+, compared to controls. The data suggest that physiological secretory stimuli to rat parotid acinar cells, which involve cyclic AMP, result in a readjustment of the basolateral membrane ATP-dependent Ca2+ pump.

8-Bromo Cyclic Adenosine Monophosphate↗
PubMed1985

Adrenergic-agonist-induced Ca2+ fluxes in rat parotid cells are not Na+-dependent.

We investigated the hypothesis that extracellular Na+ is required for the rapid mobilization of Ca2+ by rat parotid cells after adrenergic stimulation. When Na+ salts in the media were osmotically replaced with either choline chloride (+atropine) or sucrose, efflux of 45Ca2+ from preloaded cells, caused by 10 microM-(-)-adrenaline, was unchanged. Similarly adrenaline stimulated 45Ca2+ uptake into cells under nonsteady-state conditions in the presence or absence of Na+. Monensin, a Na+ ionophore, was able to elicit a modest increase in 45Ca2+ efflux, compared with controls. Studies of net 45Ca2+ flux, performed under near-steady-state conditions, showed that adrenaline caused net 45Ca2+ accumulation, whereas monensin caused net 45Ca2+ release. The effect of monensin required the presence of Na+ in the incubation medium. Both 1 mM-LaCl3 and 0.1 mM-D-600 prevented adrenaline-stimulated 45Ca2+ uptake into cells, but had no effect on monensin-induced changes. We conclude that (1) the rapid mobilization of Ca2+ by adrenergic agonists seen in rat parotid cells does not require a Na+out greater than Na+in gradient and (2) the nature of the monensin effect is quite different from the adrenergic-agonist-induced response.

Animals↗
PubMed1985

Nonspecific immunity and head and neck cancer: blastogenesis reviewed and revisited.

The present study suggests a correlation between concanavalin A-driven blastogenesis and the clinical course of head and neck cancer. Blastogenesis assays were conducted on peripheral blood lymphocytes from controls and from patients with squamous cell carcinoma (SCC) of the head and neck. Our results indicated that 3H-thymidine incorporation in response to concanavalin A and phytohemagglutinin stimulation were significantly lower for patients' than for controls' lymphocytes, whereas PWM stimulation was not statistically different in these two groups. Differences between patients and controls were most notable with concanavalin A stimulation. Five of seventeen patients had a response to concanavalin A stimulation that was in the normal range when expressed as relative to control values. The clinical course of these five patients seems to point to a better prognosis than that of the remaining patients who had below-normal mitogenic responses.

Adult↗
PubMed1984

Perturbation of cobalt 60 radiation doses by metal objects implanted during oral and maxillofacial surgery.

The influence on cobalt 60 dose distributions of typical metal parts used in oral and maxillofacial surgery was studied. Relative doses were determined by exposing x-ray films in a polystyrene phantom set-up containing samples of Vitallium, titanium, and stainless steel. Optical densities were converted to doses with the aid of sensitometric curves. The results show that for normal incidence there is a 25% to 40% increase in dose at the entrance side of the metal and a 20% to 25% decrease in dose at the exit side. The enhancement effect falls off rapidly and becomes negligible at about 1 mm from the interface. The reduction effect decreases more gradually and is still evident at distances of a few centimeters. These dose perturbations should be taken into account in the planning of radiation therapy for patients in whom metal objects have been implanted.

Absorptiometry, Photon↗
PubMed1982

Nasal septal abscess of dental origin.

A nasal septal abscess can be a serious complication of trauma or surgery. Dental infections that lead to this condition are rarely mentioned in the dental literature, and no report was found in the English otorhinolaryngological literature. As septal suppuration causes destruction of the cartilaginous septum, saddle-nose formation, and severe intracranial complications, immediate treatment is necessary. Two patients had septal abscesses as a complication of dental infection. Development of the condition, possible complications, and treatment are discussed.

Abscess↗