Medical arthroscopy--emerging era of rheumatological intervention

OBJECTIVE

To evaluate the safety and diagnostic value of arthroscopy performed by a rheumatologist.

METHODS

Decisions for performing arthroscopy were taken when detailed clinical history-and relevant rheumatological investigations failed to arrive at a definite diagnosis. Arthroscopies were performed under local anesthesia as a daycare procedure. Synovial biopsies taken during procedures were subjected to histopathological examination (HPE).

RESULTS

Of the 50 patients enrolled, 39 were males while 11 were females with mean age of 35.5 years. In lower limb oligoarthritis group of patients, three had macroscopic picture of crystal arthropathy, rest of the 29 patients revealed gross picture indicative of non-specific synovitis. While in polyarticular group of eight patients, three had macroscopic picture suggestive of crystal arthropathy (probably polyarticlar gout) while five were indicative of rheumatoid arthritis. In monoarticular disease pattern (n= 10) macroscopic picture findings were as follows- crystal arthropathy-two, tubercular-three, synovial chondromatosis-one and non-specific synovitis-two. HPE of synovium did not correlate in many cases.

CONCLUSION

Arthroscopy using a 4 mm scope under local anesthesia in the hands of rheumatologists is a safe daycare procedure. In few cases arthroscopy helped in arriving at a final diagnosis but many patients remained undiagnosed. Both the rheumatologists and the pathologists require further experience in this field.

Resistance to UV-induced apoptosis in human keratinocytes during accelerated senescence is associated with functional inactivation of p53

Compared to proliferating keratinocytes (KCs), growth-arrested KCs are relatively resistant to UV-light induced apoptosis. When KCs undergo confluency, or following exposure to anti-proliferative agents such as IFN-gamma plus a phorbol ester-12-O-tetradecanoylyphorbol-13-acetate (TPA), they convert from a proliferative to a nonproliferative state resembling senescence. Since p53 regulates UV-induced apoptosis of KCs, this report further characterizes p53 half-life, post-translational modifications, and transcriptional activity using cultured human KCs and living epidermal equivalents. The half-life of p53 in KCs was longer than fibroblasts (greater than approximately 3 h vs. 30 min). Exposure of proliferating KCs to UV-light induces post-translational modifications of p53 including acetylation of lysine-382 residues. By contrast, KCs undergoing irreversible growth arrest following confluency, or exposure to IFN-gamma plus TPA, were resistant to UV-induced apoptosis, and failed to undergo the acetylation modification of p53. Exposure of KCs to IFN-gamma plus TPA reduced total cellular p53 levels and reduced the transcriptional activity of p53. Addition of Trichostatin A (TSA), an inhibitor of de-acetylation, increased acetylation of lysine-382 in confluent KCs, thereby enhancing susceptibility of confluent cultures to UV-induced apoptosis. Pre-treatment of epidermal equivalents with IFN-gamma plus TPA also blocked UV-light induced increase in p53 levels, and reduced apoptosis. In conclusion, these studies demonstrate that growth arrested KCs may resist UV-light induced apoptosis by inactivating the pro-apoptotic function of p53.

Synthesis of galactopyranosyl amino alcohols as a new class of antitubercular and antifungal agents

The galactopyranosyl amino alcohols (3-16) were synthesised by regioselective oxirane ring opening of compound 2 with variety of amines and screened for antitubercular and antifungal activities. One of the compounds (16) showed potent activity against Mycobacterium tuberculosis H37 Rv in vitro and also displayed activity in MDR TB. The compound (16) was found to be superior to ethambutol clinically used anti TB drug in in vitro screen.

Synthesis and antimycobacterial activity of 3,5-disubstituted thiadiazine thiones

A series of 3,5-disubstituted thiadiazine thiones (4-24) have been synthesized by reaction of primary amines with carbon disulphide followed by cyclocondensation of the resulting intermediate with formaldehyde and primary amines or amino acids. The compounds were screened for antitubercular activity in vitro against Mycobacterium tuberculosis H37Rv. Three compounds 4, 12 and 18 showed antimycobacterial activity with MIC 12.5 microg/mL. Compound 4, was tested in vitro against five multidrug resistant (MDR) strains of M. tuberculosis and was found to be active. Compound 4 also exhibited activity in vivo. While all the mice died in the untreated group, the mean survival time (MST) of the compound treated mice was enhanced, 33% mice were surviving in treated group and the load of bacilli in the lung was considerably less in the compound treated group than in the untreated control group.

Optimal testing conditions for determining MICs and minimum fungicidal concentrations of new and established antifungal agents for uncommon molds: NCCLS collaborative study

This collaborative three-center study evaluated NCCLS M38-A document testing conditions and other testing conditions for the antifungal susceptibility testing of 35 isolates of Aspergillus nidulans, A. terreus, Bipolaris hawaiiensis, B. spicifera, Cladophialophora bantiana, Dactylaria constricta, Fusarium solani, Paecilomyces lilacinus, Scedosporium prolificans, Trichoderma longibrachiatum, and Wangiella dermatitidis for itraconazole, three new triazoles (voriconazole, posaconazole, and ravuconazole), and amphotericin B. MICs and minimum fungicidal concentrations (MFCs) were determined in each center by using four media (standard RPMI-1640 [RPMI], RPMI with 2% dextrose [RPMI-2%], antibiotic medium 3 [M3], and M3 with 2% dextrose [M3-2%]) and two criteria of MIC determination (complete growth inhibition [MICs-0] and prominent growth inhibition [MICs-2]) at 24, 48 and 72 h. MFCs were defined as the lowest drug concentrations that yielded <3 colonies (approximately 99 to 99.5% killing activity). The reproducibility (within three wells) was higher among MICs-0 (93 to 99%) with either RPMI or M3 media than among all MICs-2 (86 to 95%) for the five agents at 48 to 72 h. The agreement for MFCs was lower (86 to 94%). Based on interlaboratory agreement, the optimal testing conditions were RPMI broth, 48 to 72 h of incubation and 100% growth inhibition (MIC-0); MFCs can be obtained after MIC determination with the above optimal testing parameters. These results warrant consideration for inclusion in the future version of the NCCLS M38 document. However, the role of these in vitro values as predictors of clinical outcome remains to be established in clinical trials.

Jagged-1 mediated activation of notch signaling induces complete maturation of human keratinocytes through NF-kappaB and PPARgamma

Establishing an effective epidermal barrier requires a series of coordinated molecular events involving keratinocytes (KCs) within a stratified epithelium. Epidermal maturation depends on convergence of pathways involving components of NF-kappaB and peroxisome proliferator activated receptor (PPAR) signaling systems that promote terminal differentiation and production of a stratum corneum. The Notch-1 receptor and its ligand Delta-1 have been proposed by others to participate in early events in KC differentiation. Here, we establish differential expression patterns for several Notch receptors and ligands in normal human skin. These immunolocalization findings, together with functional studies demonstrating increased levels of Notch ligand/receptors occurring during the onset of differentiation, prompted use of a soluble Notch ligand, a peptide derived from the most conspicuously expressed ligand in skin, Jagged-1. Exposing submerged KC monolayers to this peptide (JAG-1) in co-presence of elevated calcium ion concentration, produced stratification with loricrin expression. Using a living human epidermal equivalent (EE) model system, when submerged cultures were raised to an air/liquid interface to generate a fully mature epidermis, activation of Notch signaling was detected. Addition of JAG-1 peptide to submerged EEs was sufficient to induce epidermal maturation. Moreover, a soluble decoy Notch inhibitor prevented such differentiation and corneogenesis in human EEs exposed to either an air/liquid interface or to the JAG-1 peptide. In KC monolayers, addition of JAG-1 peptide induced IKKalpha mediated NF-kappaB activation, as well as increased PPARgamma expression. Immunoprecipitation/Western blot analysis revealed a physical association between the p65 subunit of NF-kappaB and PPARgamma. These results indicate that activation of Notch signaling is necessary for maturation of human epidermis, and activation by a soluble Notch ligand is sufficient to trigger complete KC differentiation including cornification.

Antifungal susceptibility testing: practical aspects and current challenges

Development of standardized antifungal susceptibility testing methods has been the focus of intensive research for the last 15 years. Reference methods for yeasts (NCCLS M27-A) and molds (M38-P) are now available. The development of these methods provides researchers not only with standardized methods for testing but also with an understanding of the variables that affect interlaboratory reproducibility. With this knowledge, we have now moved into the phase of (i) demonstrating the clinical value (or lack thereof) of standardized methods, (ii) developing modifications to these reference methods that address specific problems, and (iii) developing reliable commercial test kits. Clinically relevant testing is now available for selected fungi and drugs: Candida spp. against fluconazole, itraconazole, flucytosine, and (perhaps) amphotericin B; Cryptococcus neoformans against (perhaps) fluconazole and amphotericin B; and Aspergillus spp. against (perhaps) itraconazole. Expanding the range of useful testing procedures is the current focus of research in this area.

Role of NF-kappaB activity in apoptotic response of keratinocytes mediated by interferon-gamma, tumor necrosis factor-alpha, and tumor-necrosis-factor-related apoptosis-inducing ligand

An important step in tumorigenesis involves loss of sensitivity to various apoptotic signals by malignant cells, imbuing them with an enhanced survival phenotype. NF-kappaB also regulates epidermal thickness, susceptibility to apoptosis, and tumor formation in skin. Keratinocytes were examined for their susceptibility to apoptosis using cytokines produced during an immunologic response to tumor antigens, i.e., interferon-gamma and/or tumor necrosis factor-alpha (TNF-alpha). The role for NF-kappaB in this response was examined using a retroviral vector containing a degradation-resistant form of IkappaBalpha. Whereas interferon-gamma and TNF-alpha either alone or in combination did not induce apoptosis in keratinocytes, after infection with the retrovirus to block NF-kappaB activation they became susceptible to TNF-alpha but not Fas-induced apoptosis. Moreover, when keratinocytes with repressed NF-kappaB activity were simultaneously treated with interferon-gamma, there was a synergistic induction of apoptosis by TNF-alpha that was dependent on FADD, tumor-necrosis-factor-related apoptosis-inducing ligand (TRAIL), and caspase activation. Molecular abnormalities accompanying repressed NF-kappaB activity included failure to induce TNF-RII receptor together with enhanced levels of TRAIL death receptor 4. The ability of interferon-gamma when combined with TNF-alpha to mediate keratinocyte apoptosis included induction of TRAIL coupled with diminished capacity of keratinocytes with repressed NF-kappaB activity to increase the TRAIL decoy receptor-1, as well as lower levels of several NF-kappaB-dependent antiapoptotic proteins accompanied by enhanced caspase 8 levels. These results indicate that interferon-gamma and TNF-alpha synergistically induce keratinocyte apoptosis when concomitant induction of NF-kappaB is blocked. Participants in the apoptotic response mediated by NF-kappaB, besides cell-survival proteins, include modulation of TRAIL and both death and decoy receptors. Thus, not only does NF-kappaB signaling influence the intrinsic survival pathway for keratinocytes in normal skin, but it may also play a role in determining the apoptotic response to cytokines generated during an immune response via TRAIL produced by the keratinocytes themselves.

Optimal susceptibility testing conditions for detection of azole resistance in Aspergillus spp.: NCCLS collaborative evaluation. National Committee for Clinical Laboratory Standards

The most important role of susceptibility testing is to identify potentially resistant isolates for the agent being evaluated. Standard testing guidelines recently have been proposed for antifungal susceptibility testing of filamentous fungi (molds). This collaborative (eight centers) study evaluated further newly proposed guidelines (NCCLS, proposed standard M38-P, 1998) and other testing conditions for antifungal susceptibility testing of Aspergillus spp. to itraconazole and three new triazoles, posaconazole (SCH56592), ravuconazole (BMS-207147), and voriconazole. MICs of itraconazole, posaconazole, ravuconazole, and voriconazole for 15 selected isolates of three species of Aspergillus (A. fumigatus, A. flavus, and A. terreus) with well documented in vitro, clinical, or animal data were determined in each center by using four medium formulations (standard RPMI-1640 [RPMI], RPMI with 2% dextrose, antibiotic medium 3 [M3], and M3 with 2% dextrose) and two criteria of MIC determination (complete [MIC-0s] and prominent [MIC-2s] growth inhibition) at 24, 48, and 72 h. The highest reproducibility (92 to 99%) was seen with the standard RPMI and M3 media. Moreover, the distinction between itraconazole-resistant (MICs of >8 microg/ml for clinically resistant strains) and -susceptible (MICs of 0.03 to 1 microg/ml) isolates, as well as between a voriconazole-resistant laboratory mutant and other isolates (voriconazole MICs of 2 to >8 versus 0.12 to 2 microg/ml), was more consistently evident with the standard RPMI medium and when MIC-0s were determined at 48 h. These results provide further refinement of the testing guidelines for susceptibility testing of Aspergillus spp. and warrant consideration for inclusion in the future NCCLS document M38-A.

Prevalence of vaginal colonization by drug-resistant Candida species in college-age women with previous exposure to over-the-counter azole antifungals

We enrolled 382 college-age women in a cross-sectional survey to investigate the relationship between use of over-the-counter (OTC) azole-based antifungal drugs and vaginal colonization by drug-resistant Candida. This study showed no correlation (P=.506) between previous OTC exposure and colonization of drug-resistant Candida in vaginal flora. However, a small number of resistant Candida species isolates were obtained from women with a history of multiple exposures to OTC antifungals; given the widespread use of these products, this may be an emerging concern.

Prospective study of Candida species in patients at a comprehensive cancer center

Since most nosocomial systemic yeast infections arise from the endogenous flora of the patient, we prospectively evaluated the species stratification and antifungal susceptibility profile of Candida spp. associated with heavy colonization and systemic infection in patients at Memorial Sloan-Kettering Cancer Center in New York. A total of 349 Candida isolates were obtained from 223 patients during the later half of 1998. Cancer was the most common underlying disease, occurring in 91% of the patients, including 61.8% with organ and 23.7% with hematological malignancies; 4.4% of the patients had AIDS. Candida albicans was the predominant species (67.3%); among 114 non-albicans Candida spp., C. glabrata (45.6%) was the most frequent, followed by C. tropicalis (18.4%), C. parapsilosis (16.6%), and C. krusei (9.6%). The overall resistance to triazole-based agents among all yeast isolates was 9.4 and 10.8% for fluconazole and itraconazole, respectively. A total of 5% of C. albicans strains were resistant to triazole antifungals, whereas 30.8 and 46.2% of C. glabrata strains were resistant to fluconazole (MIC > or = 64 microg/ml) and itraconazole (MIC > or = 1 microg/ml), respectively. A significant association was observed between prior treatment with triazole and isolation of fluconazole-resistant C. albicans (P = 0.005, OR 36), although this relationship was not seen in C. glabrata isolates (P = 0.4). This study reinforces the importance of periodic, prospective surveillance of clinical fungal isolates to determine appropriate prophylactic, empiric, and preemptive antifungal therapy for the highly susceptible patient population.

Abnormal NF-kappaB signaling pathway with enhanced susceptibility to apoptosis in immortalized keratinocytes

The transcriptional activation and proper regulation of NF-kappaB is known to be important to the apoptotic resistant phenotype of epidermal-derived keratinocytes. By comparing and contrasting the responses of normal foreskin-derived keratinocytes versus an immortalized skin-derived keratinocyte cell line (i.e. HaCaT cells), several molecular defects involving NF-kappaB signaling pathway were delineated in the immortalized keratinocytes. While exposure to IFN-gamma plus TPA produces growth arrest in both normal and immortalized keratinocytes, with rapid phosphorylation of MEKKI and recruitment of distinctive protein kinase C isoforms into the signalosome complex, subsequent molecular events necessary for NF-kappaB activation were abnormal in HaCaT cells. This disrupted NF-kappaB activation in HaCaT cells was accompanied by enhanced susceptibility to UV-light induced apoptosis, which was associated with elevated levels of E2F-1 and decreased TRAF1/TRAF2 levels. Additional defects in HaCaT cells included markedly diminished levels of IKKbeta (and lack of induction of kinase activity) in response to inflammatory stimuli, a failure of p21(WAF1/CIP1) to associate with CDK2, and a decreased association between p65 and p300. These studies suggest caution in using HaCaT cells as a substitute for normal keratinocytes to study apoptosis in the skin. Thus, it appears that while the immortalized cells can escape cell cycle checkpoints by elevated levels of E2F-1, an adverse biological consequence of such dysregulated cell cycle control is the inability to activate the anti-apoptotic NF-kappaB signaling pathway. Therefore, exploiting this apoptosis vulnerability in pre-malignant, or immortalized cells, prior to acquiring a death-defying phenotype characteristic of more advanced malignant cell types, provides the basis for an early interventional therapeutic strategy for cutaneous oncologists.

Molecular cloning, phylogenetic analysis and three-dimensional modeling of Cu,Zn superoxide dismutase ( CnSOD1 ) from three varieties of Cryptococcus neoformans

Cryptococcus neoformans (Cn), causal agent of fungal meningoencephalitis, has three varieties with variable host predilection. To explore mechanisms for these pathogenic differences, we have characterized Cu,Zn SOD gene (CnSOD1). A Saccharomyces cerevisiae sod1Delta mutant was complemented with Cn var. grubii yeast expression library. The complementing clone had an ORF of 462 bp and the deduced 154 aa sequence showed 61% identity with S. cerevisiae SOD1 and 53-65% with other eukaryotic SOD1s. Cn var. grubii CnSOD1 cDNA was used to clone corresponding cDNAs from var. neoformans and var. gattii. ORFs from three varieties revealed 20-29% differences in deduced aa (s) with a significant 6% non-synonymous aa substitution between Cn var. grubii and Cn var. gattii. Cosmid library screening and PCR cloning were used to obtain genomic SOD1, which was split by five introns with identical placements and a typical 5' splice junction sequence, GTNNGY. These introns also showed a large nt variation among the three Cn varieties. Phylogenetic analyses revealed CnSOD1 to be in a group distinct from other eukaryotic SOD1s and with a significant divergence of the var. grubii from var. gattii. The CnSOD1 -deduced protein was modeled based on the crystal structure of S. cerevisiae SOD1, which showed an excellent fit. Most of the non-synonymous aa substitutions occurred on the outside of the molecule and these may contribute to differences in antigenicity among the three varieties. Notably, Cn var. neoformans and var. gattii Cu,Zn SOD had three substitutions of glycine (Gly26, Gly92 and Gly123 for Asn26, Ser92 and Ser123) that may contribute to the observed lower thermostability of this enzyme vis-a-vis Cn var. grubii. This is the first nucleotide and structural comparison of a protein-encoding gene from the three Cn varieties, which may provide a framework for future studies on the role of Cu,Zn SOD in Cn pathogenesis.

Candida dubliniensis at a cancer center

Candida dubliniensis, a germ tube-positive yeast first described and identified as a cause of oral candidiasis in patients with acquired immunodeficiency syndrome in Europe in 1995, has an expanding clinical and geographic distribution that appears to be similar to that of the other germ tube-positive yeast, Candida albicans. This study determined the frequency, clinical spectrum, drug susceptibility profile, and suitable methods for identification of this emerging pathogen at a cancer center in 1998 and 1999. Twenty-two isolates were recovered from 16 patients with solid-organ or hematologic malignancies or acquired immunodeficiency syndrome. Two patients with cancer had invasive infection, and 14 were colonized with fungus or had superficial fungal infection. All isolates produced germ tubes and chlamydospores at 37 degrees C, did not grow at 45 degrees C, and gave negative reactions with d-xylose and alpha-methyl-d-glucoside in the API 20 C AUX and ID 32 C yeast identification systems. Phenotypic identification was confirmed by molecular beacon probe technology. All isolates were susceptible to the antifungal drugs amphotericin B, 5-fluorocytosine, fluconazole, itraconazole, and ketoconazole.

Keratinocyte CDw60 expression is modulated by both a Th-1 type cytokine IFN-gamma and Th-2 cytokines IL-4 and IL-13: relevance to psoriasis

SUMMARY

Psoriasis is a chronic skin disease with an immunocytic infiltrate, including activated T lymphocytes, producing multiple cytokines that can influence the phenotype of epidermal keratinocytes. In these studies we examined the effect of the cytokines interferon-gamma and interleukin-13 or interleukin-4 on keratinocytes, alone and in combination, on surface levels of HLA-DR, intercellular adhesion molecule 1, and CDw60, as well as the transcription factors STAT1, STAT6, and BCL-6. As CDw60 is an acetylated form of the GD3 ganglioside and may function as a T cell costimulatory molecule, the modulation of CDw60 expression by keratinocytes in psoriatic lesions was highlighted to gain insight into potentially important T cell-keratinocyte interactions. Interferon-gamma was observed to block the interleukin-4- or interleukin-13-mediated induction of CDw60 on cultured keratinocytes, but not induction of the transcription factor STAT6. Interleukin-13 and interleukin-4 were unable to block interferon-gamma-mediated induction of STAT1 or BCL-6, however, or the upregulation of intercellular adhesion molecule 1 and HLA-DR. In psoriatic plaques, CDw60 was not consistently detected on keratinocytes in acute lesions, but was detected predominantly on basal layer keratinocytes in chronic lesions. In addition we found that BCL-6 levels were increased in psoriatic lesions; in acute lesions BCL-6 was primarily localized in the basal layer keratinocytes, whereas in chronic plaques nuclear BCL-6 was predominantly expressed by keratinocytes in the suprabasal cell layers. These studies highlight the complex modulation of the keratinocyte phenotype by immunocyte-derived cytokines, in which induction of CDw60 involving interleukin-4, or interleukin-13 was antagonized by interferon-gamma. We suggest in psoriatic plaques that the presence or absence of CDw60 expression by keratinocytes may reflect the dynamic interplay between Th-1-type cytokines such as interferon-gamma and Th-2-type cytokines such as interleukin-4 and interleukin-13. The ability of interferon-gamma to induce the transcription repressor BCL-6 may also contribute to the overall immunologic events in skin, including suppression of the intermediates in the synthetic pathway leading to expression of the T cell costimulatory ganglioside CDw60.

Flow cytometry antifungal susceptibility testing of pathogenic yeasts other than Candida albicans and comparison with the NCCLS broth microdilution test

Candida species other than Candida albicans frequently cause nosocomial infections in immunocompromised patients. Some of these pathogens have either variable susceptibility patterns or intrinsic resistance against common azoles. The availability of a rapid and reproducible susceptibility-testing method is likely to help in the selection of an appropriate regimen for therapy. A flow cytometry (FC) method was used in the present study for susceptibility testing of Candida glabrata, Candida guilliermondii, Candida krusei, Candida lusitaniae, Candida parapsilosis, Candida tropicalis, and Cryptococcus neoformans based on accumulation of the DNA binding dye propidium iodide (PI). The results were compared with MIC results obtained for amphotericin B and fluconazole using the NCCLS broth microdilution method (M27-A). For FC, the yeast inoculum was prepared spectrophotometrically, the drugs were diluted in either RPMI 1640 or yeast nitrogen base containing 1% dextrose, and yeast samples and drug dilutions were incubated with amphotericin B and fluconazole, respectively, for 4 to 6 h. Sodium deoxycholate and PI were added at the end of incubation, and fluorescence was measured with a FACScan flow cytometer (Becton Dickinson). The lowest drug concentration that showed a 50% increase in mean channel fluorescence compared to that of the growth control was designated the MIC. All tests were repeated once. The MICs obtained by FC for all yeast isolates except C. lusitaniae were in very good agreement (within 1 dilution) of the results of the NCCLS broth microdilution method. Paired t test values were not statistically significant (P = 0.377 for amphotericin B; P = 0.383 for fluconazole). Exceptionally, C. lusitaniae isolates showed higher MICs (2 dilutions or more) than in the corresponding NCCLS broth microdilution method for amphotericin B. Overall, FC antifungal susceptibility testing provided rapid, reproducible results that were statistically comparable to those obtained with the NCCLS method.

Id-1 delays senescence but does not immortalize keratinocytes

Defining the molecular basis responsible for regulating the proliferative potential of keratinocytes has important implications for normal homeostasis and neoplasia of the skin. Under current culture conditions, neonatal foreskin-derived human keratinocytes possess a relatively short replicative lifespan. Recently it was reported that forced overexpression of the helix-loop-helix protein Id-1 was capable of immortalizing keratinocytes, secondary to activation of telomerase activity and suppression of p16/Rb-mediated growth arrest pathways. To investigate the relationship between Id-1, telomerase activity, telomere length, p16, Rb cell cycle regulators, and senescence, whole populations of keratinocytes were infected with a retrovirus to induce overexpression of Id-1. In these unselected cultures, enhanced Id-1 levels clearly extended the lifespan of keratinocytes, but Id-1 did not prevent the onset of replicative senescence. Under these experimental conditions, Id-1 expression did not trigger induction of telomerase activity, and there was progressive shortening of the telomeres that was accompanied by elevated p16 levels and prevalence of active Rb. The ability of Id-1 to postpone, but not prevent, senescence may be related to partial inhibition of p16 expression, as the Id-1-overexpressing cultures displayed a decreased capacity for 12-O-tetradecanoylphorbol-13-acetate-mediated p16 induction. Thus, while no immortalization was observed, Id-1 could delay the onset of replicative senescence in unselected human keratinocyte populations.

Rapid identification of Candida dubliniensis using a species-specific molecular beacon

Candida dubliniensis is an opportunistic fungal pathogen that has been linked to oral candidiasis in AIDS patients, although it has recently been isolated from other body sites. DNA sequence analysis of the internal transcribed spacer 2 (ITS2) region of rRNA genes from reference Candida strains was used to develop molecular beacon probes for rapid, high-fidelity identification of C. dubliniensis as well as C. albicans. Molecular beacons are small nucleic acid hairpin probes that brightly fluoresce when they are bound to their targets and have a significant advantage over conventional nucleic acid probes because they exhibit a higher degree of specificity with better signal-to-noise ratios. When applied to an unknown collection of 23 strains that largely contained C. albicans and a smaller amount of C. dubliniensis, the species-specific probes were 100% accurate in identifying both species following PCR amplification of the ITS2 region. The results obtained with the molecular beacons were independently verified by random amplified polymorphic DNA analysis-based genotyping and by restriction enzyme analysis with enzymes BsmAI and NspBII, which cleave recognition sequences within the ITS2 regions of C. dubliniensis and C. albicans, respectively. Molecular beacons are promising new probes for the rapid detection of Candida species.

Limitation of the AccuProbe Coccidioides immitis culture identification test: false-negative results with formaldehyde-killed cultures

The AccuProbe Coccidioides immitis culture identification test (CI test) yielded false-negative results with formaldehyde-killed C. immitis submitted to a reference laboratory. Further evaluation with pure or mixed cultures or stored, heat-killed cultures revealed the CI test to be highly sensitive and specific for C. immitis except when the cultures were pretreated with formaldehyde.

Direct PCR of Cryptococcus neoformans MATalpha and MATa pheromones to determine mating type, ploidy, and variety: a tool for epidemiological and molecular pathogenesis studies

Cryptococcus neoformans MATalpha and MATa pheromones were amplified by direct PCR. Nucleotide sequence analyses revealed unique restriction enzyme sites. Sixty strains were used to devise a restriction fragment length polymorphism typing scheme that yielded three variety-specific patterns. Additionally, pheromone-specific PCR allowed easier identification of diploid C. neoformans strains than flow cytometry.

Stimulation in the rostral pole of monkey superior colliculus: effects on vergence eye movements

Recent studies have indicated that the superior colliculus (SC), traditionally considered to be saccade-related, may play a role in the coding of eye movements in both direction and depth. Similarly, it has been suggested that omnidirectional pause neurons are not only involved in the initiation of saccades, but can also modulate vergence eye movements. These new developments provide a challenge for current oculomotor models that attempt to describe saccade-vergence coordination and the neural mechanisms that may be involved. In this paper, we have attempted to study these aspects further by investigating the role of the rostral pole of the SC in the control of vergence eye movements. It is well-known that, by applying long-duration electrical stimulation to rostral sites in the monkey SC, saccadic responses can be prevented and interrupted. We have made use of these properties to extend this paradigm to eye movements that contain a substantial depth component. We found that electrical intervention in the rostral region also has a clear effect on vergence. For an eye movement to a near target, stimulation leads to a significant suppression and change in dynamics of the pure vergence response during the period of stimulation, but the depth component cannot be prevented entirely. When these paradigms are implemented for 3D refixations, the saccade is inactivated, as expected, while the vergence component is often suppressed more than in the case of the pure vergence. The data lead us to conclude that the rostral SC, presumably indirectly via connections with the pause neurons, can affect vergence control for both pure vergence and combined 3D responses. Suppression of the depth component is incomplete, in contrast to the directional movement, and is often different in magnitude for 3D refixations and pure vergence responses. The results are discussed in connection with current models for saccade-vergence interaction.

Genetic modeling of human urinary bladder carcinogenesis

We developed a model of human urinary bladder cancer progression from in situ precursor lesions to invasive carcinoma using whole organ histologic and genetic mapping. The model represents a high-density and detailed analysis regarding allelic losses on chromosomes 4, 8, 9, 11, and 17 as revealed by testing of 234 samples obtained from five cystectomy specimens. The samples corresponded to microscopically identified intraurothelial precursor conditions ranging from dysplasia to carcinoma in situ and invasive cancer. The initial analysis of paired normal and tumor DNA samples disclosed allelic losses in 72 of 225 tested hypervariable DNA markers. Subsequent use of these markers on all mucosal samples revealed that 47 had alterations with a statistically significant relation to urothelial neoplasia. The allelic losses clustered in 33 distinct chromosomal regions, indicating the location of putative tumor suppressor genes involved in the development and progression of urinary bladder cancer. Some of the markers with statistically significant allelic losses mapped to the regions containing well-characterized tumor suppressor genes but many were located in previously unknown loci. The majority of statistically significant allelic losses (70%) occurred early in low-grade intraurothelial dysplasia, and some of them involved adjacent areas of morphologically normal mucosa preceding the development of microscopically recognizable precursor lesions. The remaining 30% of markers developed allelic losses in the later phases of urothelial neoplasia, implicating their involvement in progression to invasive disease. Markers exhibiting allelic losses in early phases of urothelial neoplasia could be used for detection of occult preclinical or even premicroscopic phases of urinary bladder cancer, whereas markers that showed allelic losses in the later phases of the process could serve as indicators of progression to invasive disease. The approach used in this study facilitates genome-wide modeling of cancer progression and provides important chromosomal landmarks for more specific studies of multistep urinary bladder carcinogenesis.

Coccidioidomycosis in New York State

Coccidioidomycosis, a systemic fungal disease caused by Coccidioides immitis, is endemic in the southwestern United States and in parts of Mexico and Central and South America. Only sporadic cases have been reported in areas (including New York) where the disease is not endemic. We used hospital discharge records and state mycology laboratory data to investigate the characteristics of C. immitis infections among New York State residents. From 1992 to 1997, 161 persons had hospital discharge diagnoses of coccidioidomycosis (ICD9 Code 114.0 - 114.5, 114.9). From 1989 to 1997, 49 cultures from patients were confirmed as C. immitis; 26 of these patients had traveled to disease-endemic areas. Fourteen of 16 isolates had multilocus genotypes similar to those of Arizona isolates, which corroborates the travel-related acquisition of the disease. Our results indicate that coccidioidomycosis may be more common in New York residents than previously recognized. Increased awareness among health-care providers should improve timely diagnosis of coccidioidomycosis and prevention of associated illnesses and deaths among patients in nondisease-endemic areas.

Congenital urethral fistula

A case of congenital urethral fistula with an intact glanular urethra without chordee is reported with a discussion of the possible etiology and one-stage repair.

Esophageal atresia and tracheoesophageal fistula: a review of 25 years' experience

During a 25-year period (1972-1996), 585 patients with esophageal atresia with or without tracheoesophageal fistula were treated at the Department of Pediatric Surgery, SMS Medical College, Jaipur, India. Increasing awareness of the anomaly has led to early detection and referral with fewer pulmonary complications. For purposes of analysis the period has been divided into five phases, with a steady decline in overall mortality observed from 95.4% in phase 1 to 41% in phase V. Although postoperative complications have also shown a declining trend, delay in diagnosis, prematurity, low birth weight, delayed arrival at the surgical centers, sepsis, pulmonary complications including pneumonitis, and inadequate nursing care all continue to contribute substantially to lower the survival in developing countries such as ours.

Role of NF-kappaB in the apoptotic-resistant phenotype of keratinocytes

Several studies point to a role for NF-kappaB in modulating epidermal thickness and apoptotic susceptibility of keratinocytes. When phorbol esters such as 12-O-tetradecanoylphorbol-13-acetate (TPA) are topically applied, prominent epidermal thickening occurs, and exposure to interferon (IFN)-gamma promotes increased epidermal thickness producing psoriatic lesions. While keratinocytes derived from psoriatic plaque resist apoptosis, and combination of TPA and IFN-gamma activates NF-kappaB, the molecular mechanism linking NF-kappaB activation and keratinocyte apoptosis resistance was unknown. Therefore, we examined the ability of IFN-gamma plus TPA to influence NF-kappaB activity, gene expression, and response to UV light-induced apoptosis. These responses in normal keratinocytes were compared with immortalized keratinocytes (HaCaT cells). Exposure of normal keratinocytes to IFN-gamma plus TPA produced a synergistic activation of NF-kappaB, compared with when each reagent was used individually. Normal keratinocytes when exposed to IFN-gamma plus TPA acquired a resistance to UV light-induced apoptosis, which was dependent on NF-kappaB because expression of a dominant negative form of IkappaBalpha overcame the resistance. Compared with normal keratinocytes, HaCaT cells have a dysfunctional constitutive NF-kappaB signaling pathway not induced by IFN-gamma and TPA, rendering HaCaT cells highly susceptible to UV-induced apoptosis. Thus, immortalized HaCaT cells have an abnormal constitutive and dysfunctional NF-kappaB signaling system. These results provide evidence that activation and proper regulation of NF-kappaB is essential for acquisition of an apoptotic-resistant phenotype for epidermal-derived keratinocytes.

Secretory proteins of Mycobacterium habana induce a protective immune response against experimental tuberculosis

The capacity of proteins of Mycobacterium habana TMC 5135 secreted into culture medium during the mid-exponential growth phase (secretory proteins, SPs) to induce protective immunity against Mycobacterium tuberculosis H37Rv was studied in the mouse model. Mice immunized with SPs followed by a challenge with M. tuberculosis H37Rv showed lesser M. tuberculosis bacilli in their lung and spleen and survived longer than unimmunized controls. The findings suggest that SP antigens of M. habana are protective against tuberculosis infection.

Apoptosis in proliferating, senescent, and immortalized keratinocytes

Skin provides an attractive organ system for exploring coordinated regulation of keratinocyte (KC) proliferation, differentiation, senescence, and apoptosis. Our main objective was to determine whether various types of cell cycle arrest confer resistance to apoptosis. We postulated that KC cell cycle and cell death programs are tightly regulated to ensure epidermal homeostasis. In this report, simultaneous expression of cyclin-dependent kinase inhibitors (p15, p16, p21, and p27), a marker of early differentiation (keratin 1), mediators of apoptosis (caspases 3 and 8), and NF-kappaB were analyzed in three types of KCs. By comparing the response of proliferating, senescent, and immortalized KCs (HaCaT cells) to antiproliferative agents followed by UV exposure, we observed: 1) Normal KCs follow different pathways to abrupt cell cycle arrest; 2) KCs undergoing spontaneous replicative senescence or confluency predominantly express p16; 3) Abruptly induced growth arrest, confluency, and senescence pathways are associated with resistance to apoptosis; 4) The death-defying phenotype of KCs does not require early differentiation; 5) NF-kappaB is one regulator of resistance to apoptosis; and 6) HaCaT cells have undetectable p16 protein (hypermethylation of the promoter), dysfunctional NF-kappaB, and diminished capacity to respond to antiproliferative treatments, and they remain highly sensitive to apoptosis with cleavage of caspases 3 and 8. These data indicate that KCs (but not HaCaT cells) undergoing abruptly induced cell cycle arrest or senescence become resistant to apoptosis requiring properly regulated activation of NF-kappaB but not early differentiation.

Protective antigens of Mycobacterium habana are distributed between peripheral and integral compartments of plasma membrane: a study in experimental tuberculosis of mouse

Mycobacterium habana, a cultivable nonpathogenic mycobacterium provides appreciable resistance in mouse against M. tuberculosis infection. This study is aimed at identification and characterization of protective antigens of M. habana. Protective potential of antigens of cell wall (CW), cell membrane (CM), cytosol (CS) and peripheral and integral compartments of the membrane fraction of M. habana was explored against experimental tuberculosis in mouse. Peripheral and integral membrane proteins were characterized by SDS-PAGE and differential staining with silver and periodic acid. Results reveal that protective antigens are distributed in both peripheral and integral membrane compartments though such effect is dominant in the former. Polysaccharide staining showed that LAM, LM and PIMs have a preference for the detergent phase. Peripheral and integral compartments constitute, respectively, 68 and 31% of the total membrane protein.

Variation in Microbial Identification System accuracy for yeast identification depending on commercial source of Sabouraud dextrose agar

The accuracy of the Microbial Identification System (MIS; MIDI, Inc. ) for identification of yeasts to the species level was compared by using 438 isolates grown on prepoured BBL Sabouraud dextrose agar (SDA) and prepoured Remel SDA. Correct identification was observed for 326 (74%) of the yeasts cultured on BBL SDA versus only 214 (49%) of yeasts grown on Remel SDA (P < 0.001). The commercial source of the SDA used in the MIS procedure significantly influences the system's accuracy.

Estimation & significance of serum & synovial fluid malondialdehyde levels in rheumatoid arthritis

Serum and synovial fluid (SF) levels of malondialdehyde (MDA), a marker of free radical induced lipid peroxidation, were estimated in patients of rheumatoid arthritis (RA) and compared with healthy controls and patients of osteoarthritis (OA). While serum MDA levels were similar in healthy controls (0.24 +/- 0.10 nmol/ml) and OA (0.28 +/- 0.11 nmol/ml), the serum levels in RA (0.47 +/- 0.19 nmol/ml) were significantly higher as compared to both healthy controls and OA patients; and correlated with synovial fluid (SF) MDA levels. No difference was observed in SF-MDA levels in RA (0.17 +/- 0.07 nmol/ml) and OA (0.16 +/- 0.09). MDA levels did not correlate with markers of disease activity in RA like joint counts, duration of morning stiffness, erythrocyte sedimentation rate etc. Increased serum MDA levels in RA suggest the role of free radicals in the pathogenesis of this inflammatory arthropathy and support the need for further studies assessing the therapeutic role of free radical scavengers in RA.

Perturbation of combined saccade-vergence movements by microstimulation in monkey superior colliculus

Perturbation of combined saccade-vergence movements by microstimulation in monkey superior colliculus. This study investigated the role of the monkey superior colliculus (SC) in the control of visually (V)-guided combined saccade-vergence movements by assessing the perturbing effects of microstimulation. We elicited an electrical saccade (E) by stimulation (in 20% of trials) in the SC while the monkey was preparing a V-guided movement to a near target. The target was aligned such that E- and V-induced saccades had similar amplitudes but different directions and such that V-induced saccades had a significant vergence component (saccades to a near target). The onset of the E-stimulus was varied from immediately after V-target onset to after V-saccade onset. E-control trials, where stimulation was applied during fixation of a V-target, yielded the expected saccade but no vergence. By contrast, early perturbation trials, where the E-stimulus was applied soon after the onset of the V-target, caused an E-triggered response with a clear vergence component toward the V-target. Midflight perturbation, timed to occur just after the monkey initiated the movement toward the target, markedly curtailed the ongoing vergence component during the saccade. Examination of pooled responses from both types of perturbation trials showed weighted-averaging effects between E- and V-stimuli in both saccade and fast vergence components. Both components exhibited a progression from E- to V-dominance as the E-stimulus was delayed further. This study shows that artificial intervention in the SC, while a three-dimensional (3D) refixation is being prepared or is ongoing, can affect the timing (WHEN) and the metric specification (WHERE) of both saccades and vergence. To explain this we interpret the absence of overt vergence in the E-controls as being caused by a zero-vergence change command rather than reflecting the mere absence of a collicular vergence signal. In the perturbation trials, the E-evoked zero-vergence signal competes with the V-initiated saccade-vergence signal, thereby giving rise to a compromised 3D response. This effect would be expected if the population of movement cells at each SC site is tuned in 3D, combining the well-known topographical code for direction and amplitude with a nontopographical depth representation. On E-stimulation, the local population would yield a net saccade signal caused by the topography, but the cells coding for different depths would be excited equally, causing the vergence change to be zero.

Superimposed histologic and genetic mapping of chromosome 9 in progression of human urinary bladder neoplasia: implications for a genetic model of multistep urothelial carcinogenesis and early detection of urinary bladder cancer

The evolution of alterations on chromosome 9, including the putative tumor suppressor genes mapped to the 9p21-22 region (the MTS genes), was studied in relation to the progression of human urinary bladder neoplasia by using whole organ superimposed histologic and genetic mapping in cystectomy specimens and was verified in urinary bladder tumors of various pathogenetic subsets with longterm follow-up. The applicability of chromosome 9 allelic losses as non-invasive markers of urothelial neoplasia was tested on voided urine and/or bladder washings of patients with urinary bladder cancer. Although sequential multiple hits in the MTS locus were documented in the development of intraurothelial precursor lesions, the MTS genes do not seem to represent a major target for p21-23 deletions in bladder cancer. Two additional tumor suppressor genes involved in bladder neoplasia located distally and proximally to the MTS locus within p22-23 and p11-13 regions respectively were identified. Several distinct putative tumor suppressor gene loci within the q12-13, q21-22, and q34 regions were identified on the q arm. In particular, the pericentromeric q12-13 area may contain the critical tumor suppressor gene or genes for the development of early urothelial neoplasia. Allelic losses of chromosome 9 were associated with expansion of the abnormal urothelial clone which frequently involved large areas of urinary bladder mucosa. These losses could be found in a high proportion of urothelial tumors and in voided urine or bladder washing samples of nearly all patients with urinary bladder carcinoma.

Altered p53 is associated with aggressive behavior of chondrosarcoma: a long term follow-up study

BACKGROUND

p53 is a major tumor suppressor gene that has been implicated in the biology of a variety of human neoplasms, including some that affect the skeleton. Recent studies based on small numbers of cases have shown that overexpression or alteration of the p53 gene is frequently present in high grade, clinically aggressive chondrosarcomas of bone. In this study, the authors addressed the relation between overexpression and alteration of the p53 gene and the clinical aggressiveness of chondrosarcoma in a large series of patients for whom long term follow-up data were available.

METHODS

The authors analyzed the expression and/or alteration of the p53 gene in 158 cases of chondrosarcoma of bone using immunohistochemistry, single-strand conformation polymorphism, and direct sequencing. They then related the findings to various clinicopathologic parameters and long term follow-up data.

RESULTS

The presence of overexpression and/or structural alterations of the p53 gene was documented in 38.1% of chondrosarcomas of bone. A statistically significant correlation was observed between overexpression or alteration of the p53 gene and both the histologic grade of the tumor and the presence of metastasis. The probability of local recurrence free, metastasis free, and overall survival was significantly higher for patients with no overexpression or alteration of p53 than for patients with p53 overexpression or alteration.

CONCLUSIONS

Overexpression or alteration of the p53 gene is an important predictor of aggressive clinical behavior in chondrosarcoma of bone.

Efficacy of API 20C and ID 32C systems for identification of common and rare clinical yeast isolates

The abilities of the API 20C and ID 32C yeast identification systems to identify 123 common and 120 rare clinical yeast isolates were compared. API 20C facilitated correct identification of 97% common and 88% rare isolates while ID 32C facilitated correct identification of 92% common and 85% rare isolates.

Generalised wasting in a young diabetic

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Shared target selection for combined version-vergence eye movements

Primates frequently make rapid binocular eye movements to reorient gaze in both direction and depth. To explain the unequal movements made by the two eyes, it often is assumed that they result from the combined action of a conjugate saccadic system and a vergence contribution. Clearly such a scheme can only yield coordinated binocular movements if both systems are guided by a shared or coupled target selection mechanism. To investigate the degree of cooperation at this level, we studied binocular refixations to target-nontarget double-stimuli in three-dimensional (3-D) space. Binocular eye movements were recorded in seven subjects using the scleral coil technique. In the experiments, 20% of trials were composed of a green target and a red nontarget, presented at the same time, but at different locations in 3-D space. These were alternated randomly with single-target trials (80%) in which the green stimulus was presented randomly at one of eight possible positions in 3-D space. Instructions to the subject emphasized either the speed or accuracy of response. Our findings show that typical features of the saccadic response to double-stimuli (bistability, averaging, and a speed-accuracy trade-off), as found in earlier two-dimensional studies, are also prevalent for initial binocular refixations to double stimuli in 3-D space. When the first saccadic response is directed to one of the two stimuli, the vergence system almost invariably makes the same choice. Likewise, when the saccadic system makes a short-latency averaging response, the vergence system shows a similar compromise. Statistical analysis shows a high correlation between saccadic and vergence target selection, strongly suggesting that the amplitude computation process of both subsystems is due to a common target selection stage that has access to information about stimulus location in 3-D space.

Role of antigen specific circulating immune complexes in diagnosis of tuberculosis

SETTING

Tuberculosis is a public health problem worldwide. Early accurate diagnosis in patients with active disease is essential to reduce morbidity and mortality. Conventional methods for detection of Mycobacterium tuberculosis have given disappointing results.

OBJECTIVE

To evaluate the utility of detection of M. tuberculosis antigen in circulating immune complexes (CIC) for the diagnosis of tuberculosis.

METHOD

Eighty-four clinically diagnosed cases of mainly extra-pulmonary tuberculosis, 85 patients with diseases other than tuberculosis and 30 healthy controls, were evaluated for the presence of antigen of M. tuberculosis in CIC in serum using sandwich enzyme linked immunosorbent assay (ELISA).

RESULTS

In total, 22 out of 84 cases were positive for culture on Lowenstein Jensen medium; 76.5% (n = 65) of the clinically diagnosed patients (including 20 culture-positive cases) were found to be positive by ELISA. The difference in mean absorbance values of ELISA in cases of tuberculosis was significantly higher than in controls. The sensitivity of ELISA was 90.9% and the specificity was 93.04%.

CONCLUSION

Detection of M. tuberculosis antigen in CIC by ELISA has potential as a useful diagnostic tool for the rapid diagnosis of tuberculosis, especially extra-pulmonary forms where results of conventional methods of diagnosis are disappointing.

Limitations of the current microbial identification system for identification of clinical yeast isolates

The ability of the rapid, computerized Microbial Identification System (MIS; Microbial ID, Inc.) to identify a variety of clinical isolates of yeast species was compared to the abilities of a combination of tests including the Yeast Biochemical Card (bioMerieux Vitek), determination of microscopic morphology on cornmeal agar with Tween 80, and when necessary, conventional biochemical tests and/or the API 20C Aux system (bioMerieux Vitek) to identify the same yeast isolates. The MIS chromatographically analyzes cellular fatty acids and compares the results with the fatty acid profiles in its database. Yeast isolates were subcultured onto Sabouraud dextrose agar and were incubated at 28 degrees C for 24 h. The resulting colonies were saponified, methylated, extracted, and chromatographically analyzed (by version 3.8 of the MIS YSTCLN database) according to the manufacturer's instructions. Of 477 isolates of 23 species tested, 448 (94%) were given species names by the MIS and 29 (6%) were unidentified (specified as "no match" by the MIS). Of the 448 isolates given names by the MIS, only 335 (75%) of the identifications were correct to the species level. While the MIS correctly identified only 102 (82%) of 124 isolates of Candida glabrata, the predictive value of an MIS identification of unknown isolates as C. glabrata was 100% (102 of 102) because no isolates of other species were misidentified as C. glabrata. In contrast, while the MIS correctly identified 100% (15 of 15) of the isolates of Saccharomyces cerevisiae, the predictive value of an MIS identification of unknown isolates as S. cerevisiae was only 47% (15 of 32), because 17 isolates of C. glabrata were misidentified as S. cerevisiae. The low predictive values for accuracy associated with MIS identifications for most of the remaining yeast species indicate that the procedure and/or database for the system need to be improved.

Amino acids within residues 181-200 of the nicotinic acetylcholine receptor alpha1 subunit involved in nicotine binding

Structural determinants of L-[3H]nicotine binding to the sequence flanking Cys 192 and Cys 193 of the Torpedo acetylcholine receptor alpha1 subunit were investigated using synthetic peptides (residues 181-200) and fusion proteins (residues 166-211). Nicotine binding at a single concentration (30 nM) was compared with 71 peptides and fusion proteins in which individual amino acids at positions 181-200 were substituted. Substitution of Lys 185, Tyr 190, Cys 192, Cys 193, Thr 196, and Tyr 198 resulted in the greatest reduction in nicotine binding. Equilibrium binding of [3H]nicotine to peptide 181-200 revealed a binding component with an apparent KD of 1.2 microM. Substitution of Lys 185 (with Glu), His 186, Tyr 190, Cys 192, Cys 193, and Tyr 198 resulted in a significant reduction in affinity. Affinity was not affected significantly by substitution of Arg 182, Lys 185 (with Gly or Arg), Val 188, Tyr 189, Pro 194, Asp 195, Thr 196, and Asp 200. It is concluded that Lys 185, His 186, Tyr 190, Cys 192, Cys 193, and Tyr 198 play the greatest role in nicotine binding to residues 181-200 of the alpha1 subunit. Previous studies have implicated Tyr 190, Cys 192, Cys 193, and Tyr 198 in agonist binding to the acetylcholine receptor. These results confirm a role for these residues and also demonstrate a function for Lys 185 and His 186 in nicotine binding.

Tilletiopsis minor: a new etiologic agent of human subcutaneous mycosis in an immunocompromised host

We describe herein the isolation of Tilletiopsis minor from a subcutaneous cyst of a 70-year-old immunocompromised male. The diagnosis was based on repeated isolation of the fungus, observation of hyphal elements in tissue sections, the ability of the mold to grow at or near body temperature, and the achievement of a complete cure following surgery and antifungal therapy.

Superimposed histologic and genetic mapping of chromosome 17 alterations in human urinary bladder neoplasia

Multistep alterations of chromosome 17 in the progression of human urinary bladder neoplasia were studied by superimposed histologic and genetic mapping. The p53 gene was included in the analysis as a model tumor suppressor gene that is frequently involved in urothelial carcinogenesis. The strategy provided a systematic approach to the study of multistep genomic alterations that occur as neoplasia progresses from precursor intraurothelial conditions to invasive cancer. This was accomplished by sampling the entire mucosa of the organ and displaying microscopically identified invasive cancer and precursor conditions in the form of a histologic map. Subsequent isolation of DNA provided a set of samples in which the search for genetic alterations was performed and superimposed on the histologic map. This approach disclosed multifocal allelic losses of chromosome 17 in the early preinvasive phases of urothelial neoplasia. The alterations were predominantly confined to the p12-13, q22-11 and q24-25 regions. Mutations and allelic losses of the p53 gene were mapped to early preinvasive phases of urothelial neoplasia. The data provide detailed analysis of chromosome 17 allelic losses that occur in the development and progression of urothelial neoplasia and represent the first step for genome-wide modeling of multistep human urothelial carcinogenesis.

Specificity of saccadic adaptation in three-dimensional space

The saccadic system is known to exhibit a considerable degree of short-term plasticity. Earlier studies have shown that saccadic adaptation, rather than being a global process affecting all saccades equally, has a certain degree of spatial resolution. Its localized nature has become apparent from studies in the frontal plane which have shown that short-term saccadic adaptation, induced along a given meridian, transfers to only a limited range of neighbouring directions. Considering that most natural gaze shifts also have a depth component, we investigated whether the directional specificity of the saccadic adaptive system can be generalized to three-dimensional (3-D) space. Binocular eye movements were recorded in seven subjects while they made saccades to visual stimuli in the horizontal plane of regard. Experiments began by recording baseline saccades, all starting from the same fixation point to either a farther target (far saccades) or an equally eccentric nearer target (near saccades). Next, by displacing the target intra-saccadically in opposite directions in alternating far and near trials, we attempted to simultaneously reduce the gain of the far saccades while increasing the gain of the near saccades. These experiments, aimed at eliciting a state of differential gain, were specifically designed to adapt only the saccadic response, since targets were shifted along corresponding iso-vergence circles. To investigate the effect of varying the radial direction difference, similar differential gain adaptation experiments were conducted in the frontal plane for saccades along two different meridians. Our results show that when the saccadic system is pressured, it is capable of adopting different gains simultaneously for equal-direction saccades to different depth planes. Similarly, opposite gain adaptation can also be achieved in the frontal plane, but only if radial saccade directions are sufficiently separated. The fact that short-term saccadic adaptation can be shown to be directionally specific in two perpendicular planes suggests that the adaptation process is restricted to a limited volume of 3-D oculomotor space.