Biomedical subjects
S Gold
Publications and source records attributed to S Gold.
cAMP regulates morphogenesis in the fungal pathogen Ustilago maydis.
The fungal pathogen Ustilago maydis exhibits a dimorphic switch from budding to filamentous growth in response to mating interactions and environmental conditions. We have found that disruption of the uac1 gene, encoding adenylate cyclase, results in a constitutively filamentous phenotype. Budding is restored to the uac1 mutant upon growth in the presence of cAMP or by extragenic suppression because of a mutation in the ubc1 gene. The ubc1 gene encodes a type II regulatory subunit of cAMP-dependent protein kinase (PKA); defects in this gene attenuate the filamentous growth that normally occurs in response to mating and exposure to air. Growth of wild-type cells in cAMP and mutation of the ubc1 gene also cause defects in the separation of mother and daughter cells (cytokinesis) and alter bud site selection. These results indicate a key role for cAMP and PKA in morphogenesis in U. maydis; this role may be common among dimorphic fungal pathogens.
Exposure of simian virus-40-transformed human cells to magnetic fields results in increased levels of T-antigen mRNA and protein.
In its integrated form. SV-40 DNA offers an opportunity to observe the behavior of what is in effect a viral genome within a cellular genome, with transcriptional and translational products that can be clearly distinguished from those of the host cell. Exposure of SV40-transformed human fibroblasts to a 60 Hz continuous-wave sinusoidal electromagnetic (EM) field resulted in increased levels of virally derived mRNA and protein of large T-antigen. These findings provide evidence that a foreign DNA integrated into cells can be affected by EM fields under conditions known to cause increased transcripts from endogenous cellular genes.
Re: Current status of lasers in soft tissue dental surgery (J Periodontol; 1993; 64:589-602)
Explore the source record for details and available documents.
Behavioral adaptation to human immunodeficiency virus-seropositive status in children and adolescents with hemophilia.
OBJECTIVE: To examine the behavioral adaptation to human immunodeficiency virus (HIV)-seropositive status, as defined by parental report, in children and adolescents with hemophilia. RESEARCH DESIGN: A clinical descriptive study of two groups of patients as part of a longitudinal design. SETTING: A university-based comprehensive hemophilia center and department of neurology acquired immunodeficiency syndrome dementia center. PATIENTS: Forty-six male children with hemophilia divided into two groups based on HIV-seropositive (n = 18) or -seronegative (n = 28) status. None of the patients were symptomatic for acquired immunodeficiency syndrome. SELECTION PROCEDURES: All pediatric patients with documented factor VII or IX deficiency aged between 4 and 19 years at study onset and their families were eligible to participate. All subjects were recruited without regard to human immunodeficiency virus status. INTERVENTIONS: None. MEASUREMENTS AND RESULTS: Profiles of behavioral adjustment were obtained from parents' reports on the Child Behavior Checklist for the HIV-seropositive and HIV-seronegative groups. The two groups did not differ on any of the major indexes of the Child Behavior Checklist, even after adjusting for maternal education and severity of hemophilia. There also was no difference between the groups when individual cases were examined for the number of child behavior checklist scales falling within a clinically significant range. CONCLUSIONS: The current findings fail to confirm any clear evidence of behavioral problems in an asymptomatic group of HIV-seropositive children and adolescents with hemophilia.
Auditory event related potentials in chronic tinnitus patients with noise induced hearing loss.
In order to explore a possible deficit in auditory central neural activity in tinnitus with noise induced hearing loss (NIHL), auditory event related potentials (ERP) and reaction time (RT) were recorded (measures of central processing) from tinnitus patients (N = 12) and hearing and age matched controls (N = 12). Testing procedure included oddball paradigms and 1 KHz repetitive stimulus, as well as click-induced brainstem auditory evoked potentials (BAEP). ERP amplitudes (waves N1, P2 and P3) in tinnitus patients were significantly lower than in controls in all testing paradigms. No differences were found in ERP peak latencies, BAEP, RT, or response scoring. The lower ERP amplitudes may indicate attenuated or 'abnormal' auditory central processing in NIHL tinnitus patients. It is suggested that this dysfunction reflects an adaptive brain process response to the tinnitus and points to auditory central involvement in tinnitus sensation.
Ascorbic acid supplements and blood pressure. A four-week pilot study.
Explore the source record for details and available documents.
Same patients, different systems: clinical implications for the care of the elderly.
Explore the source record for details and available documents.
White fibrous papulosis of the neck.
We report a case of white fibrous papulosis of the neck in a 70-year-old Iranian woman. To date this recently reported entity has only been described in Japanese patients. This asymptomatic eruption characteristically affects the posterior neck. The pale papules are round to oval 2-3 mm in diameter, and not follicular. Histology shows thickened collagen bundles in the superficial and mid-dermis with a normal elastic pattern.
Group differences and individual classification accuracy associated with letter/word oddity problems.
The ability of 27 pairs of mildly mentally retarded and normally achieving 6- through 8-year-old students to apply an oddity rule to an experimental set of letter and word oddity problems was assessed. The mildly retarded group evidenced a markedly lower level of performance on all five experimental oddity problems, but they did evidence successful generalization to oddity arrays that visually were very different from those used in training. High levels (greater than 90%) of sensitivity, specificity, positive predictive accuracy, and negative predictive accuracy were observed using only six cards. Only slightly lower (greater than or equal to 85%) values were obtained when using a cut-off score. This subset of six cards is, therefore, an excellent candidate for inclusion in a cognitive preschool screening test being developed for the early detection of children with mild mental retardation.
Invasive treatment for coronary artery disease in the elderly.
The widespread availability of coronary artery bypass grafting and percutaneous transluminal coronary angioplasty presents important treatment options for the older patient. The findings from a number of surgical series of coronary artery bypass grafting and percutaneous transluminal coronary angioplasty are summarized. Certain trends are evident. Perioperative mortality, cardiovascular morbidity, and other complications, while declining, remain somewhat higher in elderly patients. However, the impact of age alone is slight. In both coronary artery bypass grafting and percutaneous transluminal coronary angioplasty, complications are more closely correlated with the presence of serious concomitant disease. Long-term survival and pain relief after coronary artery bypass grafting are excellent in older patients, and percutaneous transluminal coronary angioplasty may be the treatment of choice in some elderly patients with coronary artery disease. As in younger patients, prolongation of survival should not be the exclusive goal. Rather, a focus on quality of life and freedom from dependency should be seriously considered.
Angiocentric immunoproliferative lesion/T-cell non-Hodgkin's lymphoma and the acquired immune deficiency syndrome: a case report and review of the literature.
The lesions known as lymphocytic vasculitis, polymorphic reticulosis (midline malignant reticulosis, lethal midline granuloma), lymphomatoid granulomatosis, and angiocentric lymphoma form what have been collectively termed the angiocentric immunoproliferative lesions (AIL). Because of recent reports demonstrating clonal rearrangements of the T-cell receptor in these lesions, the AIL are now thought to represent a continuous spectrum of post-thymic T-cell non-Hodgkin's lymphoma (NHL). NHL associated with the acquired immune deficiency syndrome (AIDS) represents intermediate or high-grade B-cell malignancies in HIV-infected patients that may be etiologically related to the Epstein-Barr virus (EBV). There have been reports of EBV-associated T-cell NHL, AIL, and large granular lymphocyte (LGL) proliferations, as well as HIV-associated T-cell neoplasia, LGL/T-cell proliferations, and AIL. We describe a case of polymorphic reticulosis (lethal midline granuloma) arising in an HIV-infected individual, who later progressed to AIDS, and review the literature on HIV-associated and EBV-associated T-cell neoplasia, LGL/T-cell proliferations, and AIL. The etiology of this AIL/T-cell NHL, especially in relation to EBV and HIV, is discussed.
Noise and hypoxia induced temporary threshold shifts in rats studied by ABR.
Rats were exposed for 2 h either to 115 dB SPL noise, to 5% oxygen in nitrogen (hypoxia) or to both hypoxia and noise. Auditory nerve-brainstem evoked responses (ABR) to 80 dB HL clicks and threshold were recorded prior to exposure, immediately (5-10 min) after the exposure, 2 h after and 2 weeks after the exposure. The findings in each experimental animal were compared to those in the control (non-exposed) group and to those in the other groups. Thresholds were elevated in each of the experimental groups, but these were temporary threshold shifts, since 2 weeks following the exposure, threshold had returned to normal. Latencies (wave I and the IV-I interpeak latency difference- (IPLD] were prolonged in the groups exposed to hypoxia (hypoxia alone and hypoxia + noise). These results are discussed in view of possible mechanisms of these noise and hypoxia induced temporary threshold shifts.
Development of a somatic cell hybrid mapping panel and molecular probes for human chromosome 3.
A somatic cell hybrid mapping panel and molecular probes have been developed for human chromosome 3. This panel defines 11 regions for the short and long arms of the chromosome. Four hundred thirty-two probes have been mapped using these hybrids. One hundred thirty-one of these probes were derived from EcoRI and HindIII flow-sorted libraries. The remaining 301 probes were isolated from NotI boundary and random (partial MboI) libraries constructed from a hybrid that provided a relative enrichment in 3p DNA sequences. For some regions of the chromosome, significant differences in the distribution of probes were noted. This was observed for both the unique sequence flow-sorted and NotI probes. These differences are in agreement with previous suggestions that Giemsa light bands are GC-rich, and therefore gene-rich (especially housekeeping genes), and that the Giemsa dark bands may contain DNA that is more highly condensed. The isolation of probes from different types of libraries, or by different screening strategies, appears to reduce deficiencies that might arise from the use of probes derived with a more limited approach. These hybrids and probes should facilitate the construction of physical and genetic linkage maps to identify various disease loci involving chromosome 3.
Molecular cloning of the structural gene for exopolygalacturonate lyase from Erwinia chrysanthemi EC16 and characterization of the enzyme product.
The ability of Erwinia chrysanthemi to cause soft-rot diseases involving tissue maceration in many plants has been linked to the production of endo-pectate lyase E. chrysanthemi EC16 mutant UM1005, however, contains deletions in the pel genes that encode the known endopectate lyases, yet still macerates plant tissues. In an attempt to identify the remaining macerating factor(s), a gene library of UM1005 was constructed in Escherichia coli and screened for pectolytic activity. A clone (pPNL5) was identified in this library that contained the structural gene for an exopolygalacturonate lyase (ExoPL). The gene for ExoPL was localized on a 3.3-kb EcoRV fragment which contained an open reading frame for a 79,500-Da polypeptide. ExoPL was purified to apparent homogeneity from Escherichia coli DH5 alpha (pPNL5) and found to have an apparent molecular weight of 76,000 with an isoelectric point of 8.6. Purified ExoPL had optimal activity between pH 7.5 and 8.0 and could utilize pectate, citrus pectin, and highly methyl-esterified Link pectin as substrates. A PL- ExoPL- mutant of EC16 was constructed that exhibited reduced growth on pectate, but retained pathogenicity on chrysanthemum equivalent to that of UM1005. The results indicate that ExoPL does not contribute to the residual macerating activity of UM1005.
Tinnitus with normal hearing sensitivity: extended high-frequency audiometry and auditory-nerve brain-stem-evoked responses.
Extended high-frequency (HF) audiometry and auditory-nerve brain-stem-evoked responses (ABR) were carried out on two groups of subjects with normal hearing sensitivity. The experimental group comprised 17 subjects with tinnitus, while the control group consisted of age- and sex-matched subjects, not suffering from tinnitus. The aim of the study was to determine whether extended HF audiometry or ABR might reveal significant differences between these two groups of subjects with normal hearing sensitivity. In addition, the characteristics of tinnitus in subjects with normal audiograms were discussed. The results of extended HF audiometry showed no significant differences between the subjects with and without tinnitus. The ABR parameters considered were also within normal limits bilaterally. Based on the methods employed in this study, tinnitus in normal listeners does not appear to reflect appreciable damage in the cochlea or in the brain-stem auditory pathways. The authors present some suggestions for future research.