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Biomedical subjects

J Leitner

Publications and source records attributed to J Leitner.

At least 19 recordsLinked to original sources
PubMed2006

Comet 81P/Wild 2 under a microscope.

The Stardust spacecraft collected thousands of particles from comet 81P/Wild 2 and returned them to Earth for laboratory study. The preliminary examination of these samples shows that the nonvolatile portion of the comet is an unequilibrated assortment of materials that have both presolar and solar system origin. The comet contains an abundance of silicate grains that are much larger than predictions of interstellar grain models, and many of these are high-temperature minerals that appear to have formed in the inner regions of the solar nebula. Their presence in a comet proves that the formation of the solar system included mixing on the grandest scales.

Journal Article↗
PubMed2005

The mechanism of corrosion of palladium-silver binary alloys in artificial saliva.

Palladium dental casting alloys are alternatives to gold alloys. The aim of this study was to determine the electrochemical behaviour and the corrosion mechanism of binary silver-palladium alloys. Seven binary silver-palladium alloys and pure palladium and silver were tested in a model saliva solution. Electrochemical tests included corrosion potential, polarization resistance, and potentiodynamic polarization measurements. The corrosion products, which may be theoretically formed, were determined by thermodynamic calculation. The behaviour of silver and silver-rich alloys was dominated by the preferential formation of a thiocyanate surface layer, which controlled the free corrosion potential. Palladium dissolved in the form of a thiocyanate complex, but the surface became passivated by either palladium oxide or solid palladium thiocyanate layer, the thermodynamic calculations indicating preference for the oxide. Palladium-rich alloys showed evidence of silver depletion of the surface, resulting in behaviour similar to palladium. Examination of binary silver-palladium alloys has made possible determination of the role of the components of the alloys and model saliva in the corrosion behaviour. The findings are applicable to the more complex commercial dental alloys containing silver and palladium as major components.

Biocompatible Materials↗
PubMed2002

[Poisoning with a podophyllin-containing wart-treating tincture].

HISTORY AND ADMISSION FINDINGS: A 57-year-old depressive and alcohol-dependent man was admitted because of frequent nausea and vomiting and abdominal complaints after he had ingested 40 ml of a tincture for treating warts. He was under the influence of alcohol, but normally oriented and without contributory findings other than his gastrointestinal complaints and tachypnea. INVESTIGATIONS: Transaminases were raised (GOT 1197 U/l, GPT 170 U/l, gammaGT 150 U/l, LDH 2047 U/l), as were creatine phosphokinase (426 U/l) and ferritin (12 200 ng/ml). Platelet count was 36000 mm3, Leucocytes count 11 700/mm (3). Gastroscopy showed marked mucosal necrosis along the entire esophagus and the pulled-up small intestine (state after gastrectomy). DIAGNOSIS, TREATMENT AND COURSE: The patient became comatose within 5 hours, acidotic, oliguric, required ventilation and went into severe shock. The symptoms and the fact that podophyllin (pod.) was the main agent in the wart preparation confirmed the suspicion of pod. poisoning. Symptomatic and intensive care measures stabilized his critically grave condition. He was extubated on the 7th day after ingestion and on the 10th day was discharged at his own request in a relatively good general state. When he was re-admitted after 4 weeks he was without psychiatric symptoms but deeply depressed, and he had signs of a polyneuropathy in all limbs, typical of pod. toxin poisoning. CONCLUSION: Pod. toxin, a spindle poison, is the toxic agent of pod., the resin from the roots and rhizomes of various Berberis plants. While the potential toxicity of the resin, taken either orally or applied externally, has been long known, the poorly definied raw product is still being added to anti-wart tinctures.

Administration, Oral↗
PubMed2001

Preparing future aging advocates: the Oklahoma Aging Advocacy Leadership Academy.

PURPOSE: This article describes the organization, operation, and evaluation of the Oklahoma Aging Advocacy Leadership Academy (OAALA). DESIGN AND METHODS: The Academy was designed to assure the continuation of future cohorts of advocates and volunteers for aging programs and services. It is a statewide training program consisting of 10 weekend sessions. The curriculum incorporates age-related content and advocacy/leadership/voluntary skills training. Evaluation consisted of: (a) a pre-post assessment of perceived familiarity with advocacy and volunteer leadership issues; (b) post-Academy participant assessments of the quality of various aspects of the Academy; (c) post-Academy written statements about areas that were valuable and in need of change; and (d) a compilation of student volunteer and advocacy activities. RESULTS: Evaluation results indicate that the OAALA led to significant increases in perceived familiarity with issues and very positive participant assessments of quality. In addition, many participants spontaneously initiated advocacy and volunteer activities while enrolled in the Academy. IMPLICATIONS: Our experience with the Academy suggests that it is a feasible means of preparing individuals to become successful old-age advocates and volunteer leaders.

Adult↗
PubMed1999

Pyogenic osteomyelitis of the spine in the elderly: three cases of a synchronous non-axial infection by a different pathogen.

STUDY DESIGN: A retrospective chart review of patients over 65 years of age treated at the Spine Care Unit for pyogenic vertebral osteomyelitis. OBJECTIVES: To assess the reliability of peripheral blood, urine and sputum cultures in the treatment of pyogenic vertebral osteomyelitis in the elderly. SETTING: Study performed at the Spine Care Unit, Meir Hospital, Kfar-Saba, Israel. METHODS: The Meir Hospital records were searched for patients over 65 years of age, treated at the Spine Care Unit for pyogenic vertebral osteomyelitis. Charts, culture results and imaging studies were reviewed. A medline literature search was performed to survey the literature regarding pyogenic vertebral osteomyelitis in the elderly with emphasis on diagnostic imaging modalities and surgical treatment. RESULTS: Three patients were identified with concurrent peripheral infection by a different organism than the organism causing the vertebral osteomyelitis. Delay in correct diagnosis led to neurologic impairment in all patients and surgical treatment was performed in all three to drain the epidural abscess, decompress the spinal cord and obtain direct tissue culture. Following decompression and epidural abscess evacuation, one patient has functionally recovered and was ambulating with a cane, two patients did not recover and remained paraparetic and ambulate in a wheelchair. CONCLUSIONS: Pyogenic vertebral osteomyelitis in the elderly can be caused by a different pathogen than that isolated from blood, sputum or urine cultures. In the elderly, a biopsy of the vertebral lesion should be obtained for susceptibility studies prior to conservative treatment with bracing and intravenous antibiotics.

Aged↗
PubMed1997

Brucellosis of the spine with a synchronous Staphylococcus aureus pyogenic elbow infection.

Staphylococcus aureus osteomyelitis and pyogenic arthritis has a different pattern in the elderly than in the young. The axial skeleton is the most frequent site of infection and treatment is usually by intravenous antibiotics. We report a case of Staph. aureus septic arthritis of the elbow with concomitant osteomyelitis of the spine that was thought to be due to Staph. aureus, but culture of debrided material from the lesion grew Brucella in culture. We suggest that in the elderly it is advisable to obtain a tissue culture diagnosis and not to instigate therapy based on positive blood cultures or a concomitant infection.

Aged↗
PubMed1997

Ventilatory-control abnormalities in familial sleep apnea.

The role of ventilatory-control abnormalities in predisposing to familial sleep-disordered breathing (SDB) was assessed in 31 subjects 28 +/- 10 yr of age (mean +/- SD). Subjects with (n = 10) and without SDB (n = 12) were recruited from 13 families having two or more members with SDB. Nine age- and gender-matched controls were recruited from families having no member with SDB. Respiratory responses to eucapnic hypoxia, and ventilatory and occlusion pressure responses to hyperoxic hypercapnia with and without added resistive loads (6.5 cm H2O/L/s), were assessed through rebreathing. Age, FEV1, and FVC did not differ among the groups. Hypoxic responses (delta VE/delta SaO2) were significantly lower among the first-degree relatives of SDB families than among controls (-0.76 +/- 0.47 L/min/% SaO2, and -1.32 +/- 0.92 L/min/% SaO2, respectively, p < 0.05). Respiratory responses to hypercapnia during unloaded conditions were similar among the groups. With resistive loading, inspiratory impedance, as measured through the relationship of mouth occlusion pressure (P100) to inspiratory flow (VT/TI), increased with increasing hypercapnia to a greater extent in members of SDB families than in controls (0.169 +/- 0.054 cm H2O/L/min versus 0.122 +/- 0.051, respectively, p < 0.05). These data suggest that familial SDB may be based partly on a familial abnormality in ventilatory control associated with blunting of the hypoxic ventilatory response. The greater increase in impedance during inspiratory loading in members of affected families also suggests a propensity for dynamic airway narrowing.

Adult↗
PubMed1990

Sensation of dyspnea during hypercapnia, exercise, and voluntary hyperventilation.

To determine whether the intensity of dyspnea at a given level of respiratory motor output depends on the nature of the stimulus to ventilation, we compared the sensation of difficulty in breathing during progressive hypercapnia (HC) induced by rebreathing, during incremental exercise (E) on a cycle ergometer, and during isocapnic voluntary hyperventilation (IVH) in 16 normal subjects. The sensation of difficulty in breathing was rated at 30-s intervals by use of a visual analog scale. There were no differences in the level of ventilation or the base-line intensity of dyspnea before any of the interventions. The intensity of dyspnea grew linearly with increases in ventilation during HC [r = 0.98 +/- 0.02 (SD)], E (0.95 +/- 0.03), and IVH (0.95 +/- 0.06). The change in intensity of dyspnea produced by a given change in ventilation was significantly greater during HC [0.27 +/- 0.04 (SE)] than during E (0.12 +/- 0.02, P less than 0.01) and during HC (0.30 +/- 0.04) than during IVH (0.16 +/- 0.03, P less than 0.01). The difference in intensity of dyspnea between HC and E or HC and IVH increased as the difference in end-tidal PCO2 widened, even though the time course of the increase in ventilation was similar. No significant differences were measured in the intensity of dyspnea that occurred with changes in ventilation between E and IVH. These results indicate that under nearisocapnic conditions the sensation of dyspnea produced by a given level of ventilation seems not to depend on the method used to produce that level of ventilation.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1989

[Secondary implantation of posterior chamber lenses].

In 27 eyes, secondary implantation of posterior chamber lenses was performed. The precondition was the existence of a part of the posterior lens capsule with zonular fibers. After cleaning of the capsule surface by means of irrigation/aspiration as well as lysis of posterior synechiae and if necessary, anterior vitrectomy, the lens was fixated in the ciliary sulcus using air and healon. Postoperatively, the visual acuities were found to be the same or better in comparison with the preoperative readings. The two main complications were decentralization of the intraocular lens and further opacification of the posterior lens capsule.

Adolescent↗
PubMed1987

[Ultrasound biometry in childhood].

Within the last 18 months the authors have measured, in cases of juvenile cataract seen by them, the axial length of the eye and other parameters. As a control group, children from the authors' squint clinic, with various refractive errors, were examined. With the data thus gathered, correlation and regression analyses were performed, postoperative refraction values were calculated, and eye growth in phakic eyes was compared with that in aphakic eyes. Regression formulas were established which enabled the authors to calculate eye length at a given age, to determine the postoperative refraction of their juvenile cataract patients with great accuracy, and, so far, to prove that there is no significant difference between phakic and aphakic eyes as regards growth.

Adolescent↗
PubMed1987

[Development of lens opacity in children's eyes following extracapsular cataract extraction].

In a group of 14 children who underwent extracapsular cataract extraction for cataract of the posterior pole, a reopacification of the posterior capsule was observed in all 18 eyes treated. Only in four eyes, in which rupture of the posterior capsule had occurred intraoperatively, was a reoperation unnecessary. In ten eyes satisfactory removal of the opacifications was accomplished using McIntyre's aspiration cannula; in four cases lensectomy was performed because of severe fibrosis. During a follow-up period of two to eight months after the posterior capsule had been rendered clear, transparency was found to be good in eight out of ten eyes.

Cataract↗
PubMed1987

[Eye injuries in childhood].

The records of 500 eye injuries were analyzed according to age, causes, type of injury and place and time of accident. Children accounted for 16% of the cases, almost half of them between 11 and 15 years old. Forty percent of the injuries were the result of accidents while playing. An increase in the number of injuries in April, July, and on Saturdays was observed. On the basis of this investigation the authors have attempted to recommend a number of sensible preventive measures.

Adolescent↗
PubMed1985

Effects of age and respiratory efforts on the perception of resistive ventilatory loads.

The present study examined the effects of age on the ability to quantitate changes in inspiratory resistive loads using signals related to the size of the load, per se. Magnitude scaling of inspiratory resistive loads was performed in different trials during breathing at small, large, and varied size tidal volumes. Subjects were specifically instructed to scale the magnitude of the airflow resistance. In both young and older adults, the perceived magnitude of a given resistance was the same in the small-, large-, and varied-sized breath trials despite substantial differences in inspiratory duration and peak inspiratory airway pressure. The change in sensation for a given change in resistance, however, was less in the older than in the younger adults. These results indicate that airflow resistance can be scaled independently of the effort used in breathing. The perception of airflow resistance is blunted in elderly adults probably as a result of an impairment in the central nervous system processing of separate signals of pressure and flow.

Adolescent↗