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Biomedical subjects

J M Strottmann

Publications and source records attributed to J M Strottmann.

17 recordsLinked to original sources
PubMed2001

Imaging of the optic nerve and visual pathways.

The visual pathway extends from the globes anteriorly to the occipital cortex posteriorly. A wide variety of disease processes may produce visual dysfunction. Because the optic nerve is a fiber tract of the brain covered by meninges, it can be affected by many of the same pathologic processes that occur in the brain and meninges. Physical examination and diagnostic tests of visual function performed by the clinician can frequently identify the anatomic location of the causative lesion in the patient with vision loss. This enables the radiologist to optimize the imaging evaluation of the patient. This article reviews the normal anatomy of the optic nerve and visual pathways, presents computed tomography (CT) and magnetic resonance (MR) imaging techniques for evaluation of these structures, and discusses the pathologic processes intrinsic to the optic nerve and visual pathways.

Craniopharyngioma↗
PubMed2000

The prognostic significance of midline shift at presentation on survival in patients with glioblastoma multiforme.

PURPOSE: While patients with glioblastoma multiforme (GBM) who present with midline shift have a presumably worse prognosis, there is little literature evaluating the prognostic significance of this presentation in multivariate analysis in the context of other known prognostic factors. METHODS AND MATERIALS: From March 1981 to September 1993, 219 patients underwent irradiation for intracranial glioma at our institution. One hundred fourteen patients with a diagnosis of a primary GBM were analyzed for the influence of the presence of midline shift at diagnosis on survival with respect to other known prognostic factors, including age, Karnofsky performance status (KPS), and extent of surgery. Eighty-five patients (74%) presented with midline shift. Surgical treatment consisted of subtotal/total resection in 86 patients (75%). Among patients presenting with midline shift, 68 (80%) underwent subtotal/total resection before irradiation. RESULTS: Multivariate analysis of the entire cohort of patients found none of the potential prognostic factors analyzed to significantly influence survival. The overall median survival was 6 months. However, when multivariate analysis was limited to patients with a KPS of > or = 70, only the presence of midline shift and age were found to significantly influence survival. Patients with a KPS > or = 70 and with midline shift present at diagnosis had a median survival of 8 months, as compared to 14 months for those not having midline shift at presentation (p = 0.04). Patients with a KPS > or = 70 and age > 50 years had a median survival of 5 months as compared to 11 months for those < or = 50 (p = 0.02). CONCLUSION: In this series, where 80% of patients who presented with a midline shift underwent decompressive resection of GBM before irradiation, the presence of midline shift at diagnosis remained an independent prognostic factor influencing survival among good performance status patients. While the role of decompressive surgery in this setting is likely of some benefit, the extent of this benefit remains to be defined.

Adult↗
PubMed2000

Preliminary report of a phase I study of combined fractionated stereotactic radiosurgery and conventional external beam radiation therapy for unfavorable gliomas.

PURPOSE: To determine the tolerance and toxicities of fractionated stereotactic radiosurgery (FSRS) given in combination with conventional external beam radiation therapy (CEBRT). METHODS AND MATERIALS: From March 1995 to September 1998, 14 patients with previously unirradiated and unfavorable glioma (malignant glioma, n = 8; unfavorable low-grade glioma, n = 5; and recurrent glioma, n = 1) were stratified into 3 groups according to tumor volume (TV) to determine the initial FSRS dose schedule: Group A (n = 3): TV </= 5 cc (7 Gy x 2 pre- and post-CEBRT]; Group B (n = 6): 5 cc < TV </= 15 cc [7 Gy x 2 pre- and 7 Gy x 1 post-CEBRT]; and Group C (n = 5): 15 cc < TV </= 30 cc (7 Gy x 1 pre- and post-CEBRT). All patients received CEBRT to 59.4 Gy at 1.8 Gy/fraction. Dose escalation was planned, if toxicity was acceptable. RESULTS: All patients were able to complete CEBRT without interruption or experiencing disease progression. Unacceptable toxicity has been limited to patients in groups B (grade 4, n = 2/6) and C (grade 4, n = 2/5). Eight patients required reoperation, with 3 (38%) having necrosis without evidence of tumor. Eleven patients (79%) have had objective partial (>/=50% reduction, n = 2) or minor (>20% reduction, n = 9) imaging response. Follow-up ranged from 9 to 51 months (median 15 months), with 7 patients alive at 22-51 months. CONCLUSIONS: Imaging response and the ability of these patients with unfavorable intracranial gliomas to complete therapy without interruption or experiencing disease progression is very encouraging. Excessive toxicity of combined FSRS and CEBRT as evaluated thus far in this study was seen for patients with group B/C lesions. Evaluation of this novel treatment strategy with dose modification is ongoing.

Adult↗
PubMed2000

Gamma knife radiosurgery as a primary treatment for prolactinomas.

OBJECT: The purpose of this study was to estimate the efficacy of gamma knife radiosurgery (GKS) in controlling tumor growth and endocrinopathy associated with prolactinomas. METHODS: Between 1993 and 1997, 164 of 469 patients with pituitary adenomas treated by GKS harbored prolactinomas. The dose to the tumor margin ranged from 9 to 35 Gy (mean 31.2 Gy), and the visual pathways were exposed to a dose of less than 10 Gy. The mean tumor diameter was 13.4 mm. The mean follow-up time for 128 cases was 33.2 months (range 6-72 months). Tumor control was observed in all but two patients who underwent surgery 18 and 36 months, respectively, after GKS. Clinical cure was achieved in 67 cases. Clinical improvement was noted with a decrease in the hyperprolactinemia after GKS. Nonetheless, in 31 (29%) of 108 patients who were followed for more than 2 years no improvement in serum prolactin levels was demonstrated, although this could be normalized by bromocriptine administration after treatment. Nine infertile women became pregnant 2 to 13 months after GKS and all gave birth to normal children. There was no visual deterioration related to GKS. Five women experienced premature menopause. In these patients there was subtotal disappearance of the tumor and an empty sella developed. CONCLUSIONS: Gamma knife radiosurgery as a primary treatment for prolactinomas can be safe and effective both for controlling tumor growth and for normalization of prolactin hypersecretion. A higher margin dose (> or = 30 Gy) seemed to be associated with a better clinical outcome. Gamma knife radiosurgery may make prolactinomas more sensitive to the bromocriptine.

Humans↗
PubMed1995

Langerhans cell histiocytosis involving the corpus callosum and cerebellum: gadolinium-enhanced MRI.

Langerhans cell histiocytosis is a systemic disorder consisting of abnormal histiocyte proliferation, in the form of focal deposits. Central nervous system involvement is most common in the hypothalamus, although other sites have been described, such as the cerebellum and the meninges. We present a case with presumed involvement of the corpus callosum and cerebellum, demonstrating gadolinium enhancement on MRI.

Adolescent↗
PubMed1995

Combined effects of magnetization transfer and gadolinium in cranial MR imaging and MR angiography.

Magnetization transfer (MT) imaging is an MR technique in which image contrast is altered by applying RF pulses that saturate a restricted pool of hydrogen protons associated with cell membranes, proteins, and other macromolecules. Protons in this restricted pool, unlike those in tissue-free water, are not visible on MR due to their short T2 relaxation times. However, these restricted protons modulate the observed signal from free water by dipolar and chemical exchange interactions. In MT imaging, specifically tailored RF pulses are applied to saturate selectively the restricted macromolecular pool. This saturation is "transferred" to the free protons, causing their signal amplitude to decrease [1]. Increased signal intensity due to T1 shortening caused by gadolinium administration does not depend upon macromolecular interactions and is not appreciably suppressed by MT pulses (Fig. 1). Consequently, MT pulses act synergistically with gadolinium to increase the visibility of enhancing lesions by preferentially suppressing nonenhancing background tissue [2]. The purpose of this paper is to demonstrate the principles underlying the synergistic effects of MT saturation and paramagnetic contrast agents and to illustrate these effects in clinical MR imaging and MR angiography.

Brain↗
PubMed1985

Refolding a disulfide dimer of cytochrome c.

A covalent dimer of Saccharomyces cerevisiae iso-1 cytochrome c is stabilized by an interchain disulfide bond involving the cysteine residue penultimate to the C-terminus. The individual chains in the dimer appear to retain the tertiary structural features characteristic for monomeric cytochrome c albeit with some perturbation. The dimer is reversibly denatured by heat, urea, or guanidine hydrochloride in a single cooperative transition whose midpoint is less than that of the monomeric protein. The kinetic profile observed for the refolding of the denatured dimer is characteristic for monomeric cytochromes except for a markedly enhanced slow-phase amplitude.

Circular Dichroism↗
PubMed1984

Spectral studies of horse heart porphyrin cytochrome c.

Removal of the heme iron from cytochrome c to generate porphyrin cytochrome c relieves the quenching of porphyrin fluorescence and enhances the fluorescence of the single tryptophan residue and the 4 tyrosine residues. The intensity of the porphyrin fluorescence is not perturbed by denaturation of the protein at neutral pH using either urea or guanidine hydrochloride. However, the amplitude of tryptophan fluorescence is increased by these denaturants from 5 to about 85% of a model tryptophan residue using solutions of 2 microM tryptophan. In contrast to cytochrome c, the tryptophan fluorescence amplitude of denatured porphyrin cytochrome c is independent of pH over the range pH 3.0 to 7.4. Acidification of solutions of either native or denatured porphyrin cytochrome c markedly alters both the visible absorbance and fluorescence of the protein consistent with protonation of two pyrrole nitrogens on the porphyrin. Preliminary analysis of the spectral changes occurring in the acid transition suggests the presence of an intermediate form having only one of these two pyrrole nitrogens protonated.

Animals↗
PubMed1983

Advantages of preelectrophoretic conjugation of polypeptides with fluorescent dyes.

A rapid simple procedure is described for the conjugation of proteins, glycoproteins, and peptides with the fluorescent dye fluorescein isothiocyanate during the time required to polymerize a polyacrylamide gel. Such conjugation does not perturb the electrophoretic mobility of the polypeptides in detergent containing gels. The location of polypeptide . dye conjugate is evident by inspection immediately upon removal of a gel from an electrophoresis cabinet avoiding the time required for postelectrophoretic staining and destaining procedures. The sensitivity of detection of polypeptide . fluorescein conjugates is at least equivalent to that obtained using Coomassie blue.

Animals↗
PubMed1983

A globular high spin form of ferricytochrome c.

Acidification of a salt-free solution of native low spin globular horse heart ferricytochrome c with HCl causes a single cooperative transition centered at pH 2.5 at 23 degrees C resulting in the formation of denatured high spin ferricytochrome c. By contrast, acidification with HCIO4 uncouples denaturation from the spin-state transition, resulting in the formation of a globular high spin form of ferricytochrome c at pH 0.0 exhibiting only modest conformational differences from native cytochrome c as judged by far ultraviolet circular dichoroic, tryptophan fluorescence, and reduced viscosity measurements. This uncoupling is consistent with the preferential binding of two perchlorate anions to the globular form(s) cytochrome c. The acid spin-state transition of the perchlorate complex is biphasic, having midpoint values at pH 0.7 and 3.6 involving 1.0 and 1.6 protons, respectively, when measured in the presence of 1 M perchlorate.

Animals↗
PubMed1981

Prediction of neutral salt elution profiles for affinity chromatography.

Neutral salts exhibit very marked differences as eluants of proteins from affinity columns. We observe: (i) that the relative potencies of neutral salts as eluants are independent of the protein or the affinity ligand in the systems studied, (ii) that the absolute salt concentration necessary to elute any given protein bound to the affinity matrix is proportional to the algebraic sum of a set of elution coefficients defined herein for the separate ions present in the solution, and (iii) that the proportionality between elution potency and elution coefficient is a function of the affinity of the protein for the immobilized ligand. Given the concentration of one neutral salt required for elution of a protein of interest from an affinity column, the elution capability of any neutral salt at any temperature can be quantitatively predicted for that protein. Accordingly, application and elution protocols for affinity chromatography can be designed to optimize the yield and fold purification of proteins.

Adenosine Triphosphate↗
PubMed1980

Affinity chromatography in nonionic detergent solutions.

Anionic dye affinity chromatography is commonly unproductive in the presence of nonionic detergents used to extract particulate proteins. Using lactate dehydrogenase as a model protein, Cibacron blue F3GA as a model dye, and Triton X-100 as a model detergent, we find that the dye is encapsulated in nonionic detergent micelles, rendering the dye incapable of ligation with the enzyme. However, the dye can be liberatd from the micelles without altering the nonionic detergent concentration by addition of an anionic detergent, such as deoxycholate or sodium dodecyl sulfate, forming mixed anionic/nonionic micelles that displace the anionic dye. Encapsulation of the anionic detergents prevents their activity as protein denaturants. These observations have been successfuly translated to the dye affinity chromatography of a detergent extract of brain particulate cyclic nucleotide phosphodiesterase.

Animals↗