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Biomedical subjects

R A Fischer

Publications and source records attributed to R A Fischer.

At least 19 recordsLinked to original sources
PubMed2004

Redox chemistry of Cu colloids probed by adsorbed CO: an in situ attenuated total reflection Fourier transform infrared study.

The IR spectroscopic investigation of both the adsorption of carbon monoxide and the interaction of oxygen and CO on the surface of copper colloids is described for the first time. The copper colloids were produced by pyrolysis of [Cu(OCH(Me)CH(2)NMe(2))(2)] in hot n-hexadecylamine. Upon contact to synthetic air Cu/Cu(x)O core-shell particles are formed. The treatment of these particles with CO results in the reestablishment of pure Cu(0) particles. These results demonstrate that small molecules penetrate the ligand shell of the nanoparticles and reversibly adsorb at the surface without affecting the particle morphology and size distribution.

Letter↗
PubMed2004

Fabrication of self-assembled monolayers exhibiting a thiol-terminated surface.

We compare two different strategies for fabricating self-assembled monolayers (SAMs) exhibiting a thiol-terminated organic surface, which recently has attracted considerable interest with regard to the binding of metal, and in particular gold particles, to these organic surfaces. Results obtained by IR spectroscopy and scanning tunneling microscopy (STM) reveal that the straightforward approach, namely, using the corresponding organodithiols, typically leads to the formation of disordered, ill-defined surfaces. We demonstrate that high-quality organothiolate adlayers exhibiting an SH-terminated surface can be prepared using dithiols where one of the thiol groups is protected by a thioester group. After formation of the organothiolate adlayer, the protecting group can be removed by immersion into NaOH solution. IR spectra recorded for the deprotected organothiolate adlayer reveal the presence of a highly oriented organothiolate adlayer.

Journal Article↗
PubMed2000

Transfusion-associated falciparum malaria successfully treated with red blood cell exchange transfusion.

Falciparum malaria is frequently associated with significant morbidity and mortality. The use of exchange transfusion as a therapeutic modality for severe cases of malaria has been described previously. We describe a case of a 49 year-old African American gentleman with a history of hemoglobin-SC disease who presented with a severe case of Plasmodium falciparum malaria 3 weeks after having received an infected blood transfusion. His peripheral smear showed the presence of numerous intraerythrocytic ring forms and "banana-shaped" gametocytes with a high-grade parasitemia, estimated at 18%. He was treated with antimalarial chemotherapy and also underwent a 12-unit red blood cell exchange transfusion, decreasing his parasite load to < 1%, as determined on repeat smear. It is prudent to be aware of the efficacy of this adjunctive treatment, especially with ever-increasing travel and a resultant increase in the prevalence of tropical diseases in the United States.

Black or African American↗
PubMed1997

Episodic acute hypotonia after Nd:YAG laser capsulotomy--retinal function and choroidal swelling.

In a patient with uveitis who had been treated with Nd:YAG laser capsulotomy after cataract surgery, several episodes of acute hypotonia occurred which were associated with changes in clinical tests of the eye and of visual function. Immunosuppressive and immunomodulating treatment appeared to reverse the changes in intraocular pressure and normalise the test results. The significance of these observations is discussed.

Acute Disease↗
PubMed1996

Clinical efficacy of haemorheological treatment using plasma exchange, selective adsorption and membrane differential filtration in maculopathy, retinal vein occlusion and uveal effusion syndrome.

The aim of the study was to test the clinical efficacy of haemorheological treatment with extracorporeal techniques in ocular diseases. We treated patients suffering from maculopathies of different origin: age-related (AMD, n = 17), uveitis-associated (n = 14) and myopia-associated maculopathy (n = 5). We also treated patients with uveal effusion syndrome (n = 3) and central retinal vein occlusion (n = 4) resistant to haemodilution or steroid therapy. The treatment consisted of plasma exchange, selective adsorption with a tryptophan-polyvinylalcohol adsorber and membrane differential filtration. Maculopathy patients underwent two treatments while the other patients received between 1 and 7 treatments. Pulsatile ocular blood flow was measured in 10 patients before and after therapy. The main parameter for evaluating clinical outcome was the change in visual acuity. Severe side-effects did not occur. The rheological parameters including plasma viscosity, whole blood viscosity and erythrocyte aggregation were statistically significantly lowered. Of 36 patients suffering from maculopathy, 25 showed an improvement of at least 1 line of visual acuity after therapy, 7/17 patients in AMD, 6/14 in uveitis and 0/5 in myopia improved 3 lines or more. All patients suffering from retinal vein occlusion improved at least 1 line and two showed an improvement of 3 lines or more. In uveal effusion syndrome, an improvement of 3 lines or more was reached in all patients. Plasma exchange, selective adsorption and membrane differential filtration are effective rheological treatment approaches to improving visual acuity in patients suffering from maculopathy except myopia-associated maculopathy. Efficacy in patients suffering from central retinal vein occlusion and uveal effusion syndrome was proven, even when the patients were resistant to previous haemodilution or steroid therapy. We conclude that a rheological approach should be considered before invasive methods such as laser coagulation, radiation therapy or surgery are applied.

Hemofiltration↗
PubMed1994

Statutory requirements for disclosure of breast cancer treatment alternatives.

Therapeutic options for breast cancer, particularly for early-stage disease, and increased patient participation in medical decision-making have oriented state legislatures toward ensuring that women with breast cancer have adequate information about treatment alternatives. Currently, 18 states have enacted statutes regarding physician disclosure of treatment alternatives to breast cancer patients. This paper reviews these statutes in the context of the requirements imposed on the physician as health care provider and the content of medical information presented to the patient as a consequence of the laws. State statutes were identified through the National Cancer Institute's State Cancer Legislative Database, and the statutory requirements were analyzed. For statutes requiring development of a written summary of treatment alternatives, the most recent summary was obtained through the responsible state agency, and informational content was analyzed for relevance to treatment decisions in early-stage disease. As a group, these laws address informed consent for treatment, physician behavior within the patient-physician relationship, and the medical information upon which treatment decisions are based. Individual statutes vary in the scope of the issues addressed, particularly in the responsibility placed on physicians, and treatment option summaries developed in response to this legislation vary widely in content and scope. Despite broad implications of these statutes in oncology practice, little is known about their effects on breast cancer care. Additional research is needed to define the impact of these statutes on breast cancer care, as such legislation is considered by other states for this and other diseases.

Breast Neoplasms↗
PubMed1993

Ovulation after intravenous and intramuscular human chorionic gonadotropin.

OBJECTIVE: To define the time interval from intravenous and intramuscular hCG administration to follicular wall rupture and the endocrinologic events associated with ovulation. DESIGN: Subjects were studied in two cycles and received hCG either 10,000 IU IM or 500 IU IV in a random sequence with an intervening spontaneous menstrual cycle. PATIENTS: Thirty women from the University of Vermont Reproductive Endocrinology Service with unexplained, male, or cervical factor infertility. INTERVENTIONS: Subjects underwent superovulation with clomiphene citrate followed by hCG administration when the lead follicle reached a mean diameter of 18 mm. Follicular rupture was determined by ultrasound monitoring every 2 hours starting 31 and 30 hours after intravenous and intramuscular hCG, respectively. Serum samples were obtained hourly for hormone measurements. The study was completed 2 hours after follicular rupture or 48 hours after hCG administration. RESULTS: Twenty-five subjects received both intramuscular and intravenous hCG. The mean time to ovulation was 40.4 hours after intramuscular hCG (range, < or = 36 to > or = 48 hours) and 38.3 hours after intravenous hCG (range, 33 to > or = 48 hours). No differences were noted in the time interval to ovulation or rate of change in circulating E2 and P levels after IM versus IV hCG administration. CONCLUSIONS: These findings suggest (1) ovulation occurs over a broad range of time after hCG administration; (2) ovulation does not occur in a more specific time interval after intravenous than intramuscular hCG; and (3) the rate of change in circulating E2 and P levels are not different after intravenous than intramuscular hCG.

Chorionic Gonadotropin↗
PubMed1990

Histiocytosis X of the vulva: a case report and review of the literature.

Histiocytosis X of the female genital tract is unusual. Thirty-two cases have been reported to date in the world literature. An additional case is reported herein, presenting as a vulvar ulcer in a 2.5-year-old child with osteolytic lesions of the skull, splenomegaly, and otitis media. The diagnosis of histiocytosis X may be established by identifying the Langerhans histiocyte, characterized by nuclear grooves, immunoreactivity for S-100 protein, and pentalamellar cytoplasmic structures seen by electron microscopy. Prognosis is difficult to determine with certainty. However, age of less than 2 years at presentation, multi-organ involvement, and/or organ dysfunction appear to be associated with a less favorable prognosis. The patient presented herein is currently receiving vinblastine chemotherapy for recurrence of disease, manifested as an osteolytic lesion in the skull.

Bone Diseases↗
PubMed1987

Midline foci of epileptiform activity in children and neonates.

We report the clinical and electroencephalographic (EEG) correlates of focal potentially epileptogenic discharge arising from midline sagittal vertices (Fz, Cz, Pz) in 21 children prospectively identified from among 7,051 consecutive EEGs recorded during a 27-month period. The patients range in age from neonates to 13 years. EEGs were obtained during evaluations for solitary or recurrent seizures (17/21), attention deficit disorder (2/21), psychomotor retardation (1/21), and headache (1/21). Clinical seizure types were diverse and included simple partial (5/17), complex partial (2/17), generalized tonic-clonic (4/17), mixed (2/17), and neonatal (4/17). The majority (13/21) of patients had an identifiable etiology for their disorder; CT scans verified mass lesions in two patients. Midline epileptogenic foci were present during wakefulness in 14 of 17 older children and restricted to sleep in the others. Sleep states were indeterminate in the four neonates. Midline foci were exquisitely confined to Fz, Cz, and/or Pz in 6 of 17 older children and would have been entirely missed by a recording montage that did not include vertex electrodes. In five other children, midline foci spread preferentially to the adjacent central-parietal regions and closely resembled the appearance of benign rolandic foci in the longitudinal EEG montages, a potentially serious cause of EEG misinterpretation in view of the high incidence of neuropathology in this patient group.

Adolescent↗
PubMed1986

Analysis of the effect of using two different strain rates on the acoustic emission in bone.

To study the effect of strain rate on the acoustic emission amplitude signature of bone, bovine cortical bone was milled into standard tensile specimens which were tested at two different strain rates while being monitored with acoustic emission equipment. It was demonstrated that the amplitude distribution of the acoustic events in bone is dependent on strain rate. Greater numbers of events occurred with the slower strain rate (0.0001 s-1), but these events were of lower amplitude than those emitted during the more rapid strain rate (0.01 s-1). The plot of the cumulative event amplitude distribution followed the power-law model, and the slope of this output, the b-value, represented a signature of the amplitude distribution. The mechanical test results were consistent with the behavior of a viscoelastic multi-phase composite material.

Acoustics↗
PubMed1983

Comparative analysis of serum antibody responses to Pseudomonas aeruginosa exotoxin A by cystic fibrosis and intensive care unit patients.

Pulmonary infection with Pseudomonas aeruginosa is a major cause of morbidity and mortality in cystic fibrosis (CF) patients. P. aeruginosa toxin is one of several proposed virulence factors which may be responsible for chronic P. aeruginosa infections in these patients. With a highly specific, sensitive, and quantitative radioimmunoassay (RIA) and a cell culture assay, the humoral immune responses of CF patients in terms of total antitoxin, antitoxin immunoglobulins A and M, and neutralizing antitoxin were compared with those of P. aeruginosa-infected intensive care unit patients and controls. The P. aeruginosa-infected CF patients were divided into severe and moderate disease groups based on mortality observed over an 8-year period. The intensive care unit patients were divided by the site of infection and the controls were healthy children and uninfected CF patients. Antibodies to toxin were found in the sera of all subjects by radioimmunoassay. Neutralizing antibody was associated with current infection. Elevated titers of antitoxin immunoglobulin A were found only in subjects with pulmonary P. aeruginosa infections. No significant differences in any antibody class were observed between the severe and moderate disease groups. In addition, no differences were observed in the antitoxin immune response of chronically infected CF patients and intensive care unit patients with acute pulmonary infections.

ADP Ribose Transferases↗
PubMed1982

Neisseria sicca osteomyelitis.

Neisseria sicca was identified as the cause of vertebral osteomyelitis in a male patient who had previously suffered a nonpenetrating, traumatic back injury. The identifying characteristics and antimicrobial susceptibility patterns are presented for this rare human pathogen, which heretofore has not been reported as a cause of infection localized to bone.

Humans↗