Biomedical subjects
Publications and source records attributed to M Glaser.
We examined 103 patients with vestibular neuritis (VN) in a follow-up study (5.7 to 20.5 years, mean 9.8 years). Two patients (1.9%) had developed a second occurrence of VN 29 to 39 months after the first. VN affected the contralateral ear in both and caused less severe distressing vertigo and postural imbalance. Unlike Bell's palsy and sudden hearing loss, a relapse in the same ear did not occur.
We report on a patient with a clinically diagnosed acute lymphoblastic leukemia (ALL) with partial unrecorded complex translocation events especially involving chromosomes 5, 9 and 18. At the GTG-band level the karyotype was abnormal in 20% of the analyzed cells. The complex karyotype was studied in more detail by spectral karyotyping (SKY) and multicolor banding (MCB) to characterize it in more detail. Thus, the karyotype could be described very accurately and in summary three different clones were detected, reflecting a high rate of karyotypic evolution in this patient.
The availability of a noninvasive method to detect and quantify apoptosis in tumours will enable tumour response to several cancer therapies to be assessed. We have synthesised two radiotracers, annexin V and the N-succinimidyl-3-iodobenzoic acid (SIB) derivative of annexin V, labelled with radio-iodine ((124)I and (125)I) and provided proof of the concept by assessing specific binding and biodistribution of these probes to apoptotic cells and tumours. We have also assessed the tumour uptake of [(124)I]annexin V in a mouse model of apoptosis. RIF-1 cells induced to undergo apoptosis in vitro showed a drug concentration-dependent increased binding of [(125)I]annexin V and [(125)I]SIB-annexin V. In the same model system, there was an increase in terminal deoxynucleotidyl transferase-mediated nick end labelling (TUNEL)-positive cells and a decrease in clonogenic survival. Radiotracer binding was completely inhibited by preincubation with unlabelled annexin V. In RIF-1 tumour-bearing mice, rapid distribution of [(125)I]SIB-annexin V-derived radioactivity to kidneys was observed and the radiotracer accumulated in urine. The binding of [(125)I]SIB-annexin V to RIF-1 tumours increased by 2.3-fold at 48 h after a single intraperitoneal injection of 5-fluorouracil (165 mg kg(-1) body weight), compared to a 4.4-fold increase in TUNEL-positive cells measured by immunostaining. Positron emission tomography images with both radiotracers demonstrated intense localisation in the kidneys and bladder. Unlike [(124)I]SIB-annexin V, [(124)I]annexin V also showed localisation in the thyroid region presumably due to deiodination of the radiolabel. [(124)I]SIB-annexin V is an attractive candidate for in vivo imaging of apoptosis by PET.
Up to now, there have been only a few valid epidemiological investigations of dizziness or vertigo as key symptoms. According to an analysis of 4,214 patients examined between 1989 and 2002 in an outpatient dizziness unit, benign peripheral paroxysmal positional vertigo (BPPV) and phobic postural vertigo (PPV) constitute the two most frequent syndromes. In this study, the relative age and sex distribution of both disorders was analysed. In the age group from 20 to 50 years, PPV was comparatively the most frequent form of dizziness, with a share of 22% to 26%. When left untreated, PPV becomes chronic in most cases and leads to considerable impairments, also at work. However, when diagnosed correctly, it can be treated successfully in more than 70% of cases. Thus, it takes on considerable medical and socioeconomic significance and should be part of the diagnostic repertoire of every doctor.
A patient with anterior semicircular canal dehiscence syndrome underwent surgical patching that caused an isolated dysfunction of the left anterior semicircular canal postoperatively. He exhibited significant ocular torsion toward the side of the affected labyrinth (17 degrees excyclotropia of the ipsilateral eye), but no displacement of the subjective visual vertical. This dissociation suggests that an isolated ocular torsion may occur after an anterior semicircular canal lesion. A combined ocular torsion and subjective visual vertical tilt, which is usually seen with vestibular lesions, requires an associated otolith dysfunction.
[A(14)-*I]iodoinsulin was prepared for studies to assess the suitability of labeled iodoinsulin for positron emission tomography (PET). Iodine-125 was used to establish the methods and for preliminary studies in rats. Further studies and PET scanning in rats were carried out using iodine-124. Tissue and plasma radioactivity was measured as the uptake index (UI = [cpm x (g tissue)(-1)]/[cpm injected x (g body weight)(-1)]) at 1 to 40 min after intravenous injection of either [A(14)-(125)I]iodoinsulin or [A(14)-(124)I]iodoinsulin. For both radiotracers, initial clearance of radioactivity from plasma was rapid (T(1/2) approximately 1 min), reaching a plateau (UI = 2.8) at approximately 5 min which was maintained for 35 min. Tissue biodistributions of the two radiotracers were comparable; at 10 min after injection, UI for myocardium was 2.4, liver, 4.0, pancreas, 5.4, brain, 0.17, kidney, 22, lung, 2.3, muscle, 0.54 and fat, 0.28. Predosing rats with unlabelled insulin reduced the UI for myocardium (0.95), liver (1.8), pancreas (1.2) and brain (0.08), increased that for kidney (61) but had no effect on that for lung (2.5), muscle (0.50) or fat (0.34). Analysis of radioactivity in plasma demonstrated a decrease of [(125)I]iodoinsulin associated with the appearance of labeled metabolites; the percentage of plasma radioactivity due to [(125)I]iodoinsulin was 40% at 5 min and 10% at 10 min. The heart, liver and kidneys were visualized using [(124)I]iodoinsulin with PET.
Adenylate kinase (AKe) from E. coli is a small, single-chain, monomeric enzyme with no tryptophan and a single cysteine residue. We have constructed six single-Trp mutants of AKe to facilitate optical studies of these proteins and to specifically examine the interrelationship between their structure, function, dynamics, and folding reactions. In this study, the effects of hydrostatic pressure on the folding reactions of AKe were studied. The native structure of AKe was transformed to a non-native, yet pressure stable, conformation by hydrostatic pressure of about 300 MPa. This pressure lability of AKe is rather low for a monomeric protein and presumably may be attributed to substantial conformational flexibility and a correspondingly large volume change. The refolding of AKe after pressure-induced denaturation was reversible under ambient conditions. At low temperature (near 0 degrees C), the refolding process of pressure-exposed AKe mutants displayed a significant hysteresis. The observation of a slow refolding rate in the 193 region and a faster folding rate around the active site (86, 41, 73 regions) leads us to suggest that in the folding process, priority is afforded to functional regions. The slow structural return of the 193 region apparently does not hinder the more rapid return of enzymatic activity of AKe. Circular dichroism studies on the pressure-denatured Y193W mutant show that the secondary structure (calculated from far-UV spectra) returned at a rapid rate, but the tertiary structure alignment (calculated from near-UV spectra) around the 193 region occurred more slowly at rates comparable to those detected by fluorescence intensity. Denaturation of AKe mutants by guanidine hydrochloride and subsequent refolding experiments were also consistent with a much slower refolding process around the 193 region than near the active site. Fast refolding kinetic traces were observed in F86W, S41W, and A73W mutants using a fluorescence detection stopped-flow rapid mixing device, while only a slow kinetic trace was observed for Y193W. The results suggest that the differences in regional folding rates of AKe are not derived from the specific denaturation methods, but rather are inherent in the structural organization of the protein.
Nordihydroguaiaretic acid (NDGA) 1 is a constituent of the creosote bush Larrea divaricata and is well known to be a selective inhibitor of lipoxygenases. NDGA can also inhibit the platelet derived growth factor receptor and the protein kinase C intracellular signalling family, which both play an important role in proliferation and survival of cancers. Moreover, NDGA induces apoptosis in tumour xenografts. Although it is likely to have several targets of action, NDGA is well tolerated in animals. These encouraging results have prompted interest in the compound for clinical study. However, high concentrations of NDGA are required for efficacy and more potent analogues are required. We have synthesized five analogues of NDGA with different lengths of carbon bridge between the two catechol moieties in order to establish the spacing required for optimum anticancer effect and to compare their activities with NDGA. In order to ascertain if the catechol moieties are essential for anticancer activity, we prepared five analogues of NDGA containing only one hydroxyl group on each aromatic ring. NDGA 1, its racemic form 2, the catechol derivatives 5, 6 with five or six carbon atom bridges and the phenol analogues 8-11 with bridges of three to six carbon atoms all showed similar activity, with IC50 values of approximately 3-5 microM against the H-69 small cell lung cancer cell line. Analogues with shorter (3) or longer bridges (7, 12) were much less active. The most potent analogue was the biscatechol with a four-carbon bridge 4 which was > 10 times more active than NDGA and therefore represents a new lead compound in this area. Surprisingly, the tetramethyl ether 14 of this compound was slightly more active than NDGA, but the trihydroxy analogue 13 was less active than NDGA. The conformationally restricted analogue 15 was also less active than NDGA. In summary, simplification of the structure of NDGA by removal of the methyl groups has produced a new lead compound 4, which is >10 times more potent than NDGA as a proliferative inhibitor of H-69 small cell lung cancer cells.
Bis-(8-anilinonaphthalene-1-sulfonate) (bis-ANS) causes inactivation of vesicular stomatitis virus (VSV) at micromolar concentrations while butyl-ANS and ANS are effective at concentrations one and two orders of magnitude higher, respectively. VSV fully inactivated by the combined effects of 10 microM bis-ANS and 2.5 kbar hydrostatic pressure elicited a high titer of neutralizing antibodies. Incubation of VSV with >/=2 M urea at atmospheric pressure caused very little virus inactivation, whereas at a pressure of 2.5 kbar, 1 M urea caused inactivation that exceeded by more than two orders of magnitude the sum of the inactivating effects produced by urea and pressure separately. Measurements of bis-ANS fluorescence showed that increasing the urea concentration reduces the pressure required to disrupt the structure. We conclude that anilinonaphthalene sulfonate compounds inactivate VSV by a mechanism similar to that produced by pressure. The most effective antiviral compound was bis-ANS which can be used for the preparation of safe viral vaccines or as an antiviral drug eventually.
Previously, progesterone was found to regulate the initiation and biosynthetic rate of myelin synthesis in Schwann cell/neuronal cocultures. The mRNA for cytochrome P450scc (converts cholesterol to pregnenolone), 3beta-hydroxysteroid dehydrogenase (3beta-HSD, converts pregnenolone to progesterone), and the progesterone receptor were found to be markedly induced during active myelin synthesis. However, the cells in the cocultures responsible for these changes were not identified. In this study, in situ hybridization was used to determine the localization of the enzymes responsible for steroid biosynthesis. The mRNA for cytochrome P450scc and 3beta-HSD were detected only in actively myelinating cocultures and were localized exclusively in the Schwann cells. Using immunocytochemistry, with minimal staining of the Schwann cells, we found the progesterone receptor in the dorsal root ganglia (DRG) neurons. The progesterone receptor in the neurons translocated into the nuclei of these cells when progesterone was added to neuronal cultures or during myelin synthesis in the cocultures. Additionally, a marked induction of the progesterone receptor was found in neuronal cultures after the addition of progesterone. The induction of various genes in the neurons was also investigated using mRNA differential display PCR in an attempt to elucidate the mechanism of steroid action on myelin synthesis. Two novel genes were induced in neuronal cultures by progesterone. These genes, along with the progesterone receptor, were also induced in cocultures during myelin synthesis, and their induction was blocked by RU-486 (a progesterone receptor antagonist). These genes were not induced in Schwann cells cultured alone after the addition of progesterone. These results suggest that progesterone is synthesized in Schwann cells and that it can indirectly regulate myelin formation by activating transcription via the classical steroid receptor in the DRG neurons.
OBJECTIVE: The District of Columbia General Hospital has a flexible sigmoidoscopy (FS) colorectal cancer screening program. We noted that this program was underused. The aim of this study was to determine whether education could improve use of a flexible sigmoidoscopy screening program in an inner city population. METHODS: Patients undergoing screening FS 5 months before our educational initiative were compared to patients undergoing screening FS 5 months after implementation. A 1-month period was allowed for implementation. Procedure logs and GI charts were reviewed. RESULTS: A total of 121 patients underwent FS screening during our study period. Of the patients, 97% were African-American; 58% were female; and the average age was 61 yr. A total of 50 patients underwent FS in the pre-education group, and 71 patients underwent FS after implementation of our educational initiative. CONCLUSIONS: Education resulted in a 42% increase in FS screening in this inner city, predominantly African-American population. Larger scale educational initiatives should be conducted to determine whether these benefits can persist and can be improved upon.
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Esophageal cancer is the third most prevalent gastrointestinal malignancy in the world. The tumor responds poorly to various therapeutic regimens and the genetic events underlying esophageal carcinogenesis are not well understood. To identify overall chromosomal aberrations in esophageal squamous cell carcinoma, we performed comparative genomic hybridization (CGH). All 17 tumor samples were found to exhibit multiple gains and losses involving different chromosomal regions. The frequency of chromosomal loss associated with this type of tumor was as follows: in 2q (100%), 3p (100%), 13q (100%), Xq (94%), 4 (82%), 5q (82%), 18q (76%), 9p (76%), 6q (70%), 12q (70%), 14q (65%), 11q (59%), and 1p (53%). Interstitial deletions on 1p, 3p, 5q, 6q, 11q, and 12q were detected also. Chromosomal gains were displayed by chromosomes and chromosome areas: 19 (100%), 20q (94%), 22 (94%), 16p (65%), 17 (59%), 12q (59%), 8q (53%), 9q (53%), and 3q (50%). Two sites showing apparent amplification were 11q (70%) and 5p15 (47%). To validate the CGH data, we isolated a BAC clone mapping to 18q12.1. This clone was used as a probe in interphase fluorescence in situ hybridization of tumor touch preparations and allelic loss was clearly revealed. This study represents the first whole-genome analysis in esophageal squamous cell carcinoma for associated chromosomal aberrations that may be involved in either the genesis or progression of this malignancy.
We report a case of dermatomyositis occurring in association with transitional cell carcinoma of the bladder. The case illustrates the importance of a thorough search for neoplasms in elderly patients with dermatomyositis and is a reminder that bladder cancer may be a rare cause of dermatomyositis. The case also shows that successful treatment of an underlying tumour may lead to resolution of paraneoplastic dermatomyositis, and relapse of cutaneous and muscle symptoms and signs may indicate recurrence of tumour.
A case of granular cell tumour of the oesophagus in a middle-aged woman is reported. The pathological features and appearances on endoscopic ultrasound (EUS) are described, and the role of EUS in the characterization of intramural oesophageal tumours is discussed.
Temozolomide, a methylating imidazotetrazinone, has antitumor activity against gliomas, malignant melanoma, and mycosis fungoides and is presently administered as a 5-day oral schedule every 4 weeks. This Phase I study aimed to determine the maximum tolerated dose of temozolomide administered as a single oral daily dose for a continuous 6- or 7-week period, evaluate the plasma pharmacokinetics on this schedule, and compare total plasma exposure over 7 weeks with the conventional 5-day regimen. Twenty-four patients with varying tumor types (17 of 24 gliomas) received temozolomide. All had clinically evaluable, refractory disease; normal renal, hepatic, and bone marrow function; and WHO performance status < or = 2. Temozolomide was administered at 50 mg/m2/day, increasing by 25 mg/m2/day/cohort until at 100 mg/m2/day grade 4 myelotoxicity forced dose reductions to 85 mg/m2/day, then 75 mg/m2/day. At 75 mg/m2/day the regimen was extended to 7 weeks, allowing the future potential combination with irradiation for primary gliomas. Patient responses (standard Union International Contre Cancer criteria; for gliomas objective response) and toxicity were assessed. Temozolomide plasma pharmacokinetics were determined on day 1 and at the beginning of the final week of administration (n = 5). The most frequent toxicities were myelosuppression and grades 1 and 2 nausea and vomiting. Grade 4 leucopenia and thrombocytopenia occurred in one of four patients receiving 100 mg/m2/day temozolomide and in one of seven patients receiving 85 mg/m2/day. These hematological toxicities did not exceed grade 2 in 10 patients receiving 75 mg/m2/day temozolomide. One of 4 malignant melanoma patients and 7 of 17 glioma patients (41%) demonstrated tumor responses. The overall response rate for this prolonged schedule was 33% (objective response, 7 of 24 patients; partial response, 1 of 24 patients); also, 6 of 17 glioma patients maintained SD. Peak plasma temozolomide concentrations were obtained 30-90 min after oral administration. Elimination in plasma was best described by a monoexponential equation with an elimination half-life of 96 +/- 16 min. No plasma accumulation of temozolomide occurred. Toxicity was greatest in higher dose cohorts, with a resultant maximum tolerated dose of 85 mg/m2/day, whereas lower dose cohorts tolerated the schedule well. The area under the temozolomide plasma versus time curve was noncumulative between the first and last week of the schedule. Temozolomide administration of 75 mg/m2/day over a 7-week period permits a 2.1-fold greater drug exposure/4 weeks in comparison with the 5-day schedule of 200 mg/m2/day repeated every 28 days. The overall response rate was 33% (glioma patients, 41% and a further 25% SD). Temozolomide (75 mg/m2/day) for 7 weeks is the recommended starting dose for further assessment of this schedule.
The properties of phosphatidyl-L-serine (L-PS) and phosphatidyl-D-serine (D-PS) were compared. The two forms of PS have similar but nonidentical L to L phase transition temperatures. Mixtures of phosphatidylserine with phosphatidylethanolamine and cholesterol (molar ratio 1:1:2) show polymorphic behavior at higher temperatures and in the presence of Ca2+. Mixtures with L-PS undergo conversion to nonlamellar phases at lower temperatures than do similar mixtures with D-PS. The aggregation of vesicles upon addition of histones is greater for L-PS than for D-PS. With fluorescence digital imaging microscopy we could show differences in the extent of formation of histone-induced domains enriched in PS or in diacylglycerol. The most enriched domains were induced with histone in membranes containing L-PS. The MARCKS peptide showed no differences in domain formation between L-PS and D-PS. The maximal activity of protein kinase C was greater in the presence of L-PS when histone, which could form more enriched domains, was the substrate. However, with a MARCKS peptide substrate, which formed domains of equal enrichment with L-PS and D-PS, the maximal activity of protein kinase C was the same with D-PS and with L-PS. These observations demonstrate that L-PS and D-PS have different physical properties. These differences likely contribute to the greater ability of L-PS to activate protein kinase C.
Dexamethasone and progesterone have been found to accelerate the time of initiation and enhance the rate of myelin synthesis in Schwann cell/neuronal cocultures. The expression of mRNA for cytochrome P450scc (converts cholesterol to pregnenolone), 3beta-hydroxysteroid dehydrogenase (converts pregnenolone to progesterone), and the progesterone receptor were detected and markedly induced during peak myelin formation in the cocultures. The mRNA for the glucocorticoid receptor was detected, but was found to be constituitively expressed. In addition, the specific activity of 3beta-hydroxysteroid dehydrogenase was measured and found to increase by 10-fold. The mRNA for cytochrome P450scc and 3beta-hydroxysteroid dehydrogenase also were found to be induced during the differentiation of O-2A precursor cells to oligodendrocytes. Fibroblast growth factor and platelet-derived growth factor were found to have proliferative effects on Schwann cells, but they had no effect on the initiation or the rate of myelin formation. These results demonstrate that myelin-forming cells have inducible enzymes responsible for steroid biosynthesis and suggest a critical role for endogenous steroid hormones in signaling the initiation and enhancing the rate of myelin formation.