PubMed Health⌕ Search

Biomedical subjects

J Cohn

Publications and source records attributed to J Cohn.

At least 127 records · Page 7Linked to original sources
PubMedDate not supplied

Histoplasmosis of the larynx.

INTRODUCTION: Laryngeal histoplasmosis was first described in 1952. Since then, fewer than 100 cases had been reported. This dimorphic fungus is endemic in the Mississippi and Ohio River Valleys. The yeast phase is responsible for human infection. METHODS: We report a 44-year-old woman who developed laryngitis. The markedly abnormal larynx, which could have been mistaken for papillomatosis, was biopsied, at which time the diagnosis of histoplasmosis was confirmed. Treatment with oral ketoconazole was instituted. RESULTS: Objective voice assessment showed abnormalities of maximum phonation time, speaking fundamental frequency, perturbation, percent voicing, mean flow rate, and spectral pattern. Subsequent to antifungal therapy, objective measures were improved. CONCLUSION: This represents the first case of laryngeal histoplasmosis in which response to therapy is documented by objective vocal assessment.

Adult↗
PubMedDate not supplied

Lead exposure potentiates the effects of NMDA on repeated learning.

Several studies now suggest that Pb exposure disrupts NMDA receptor complex function, findings which may have implications for understanding the basis of Pb-induced learning impairments. To further evaluate this possibility, the behavioral properties of the glutamate agonist NMDA were compared in rats that had been chronically exposed to 0, 50, or 250 ppm Pb acetate in drinking water from weaning. Acute administration of NMDA (20-50 mg/kg IP) decreased accuracy in both the repeated acquisition (RA) and performance (P) components of this multiple schedule with a selective effect on the learning component in the second half of the session. Analyses of error patterns revealed that the disruption of RA accuracy derived from initial perseverative errors followed by errors of skipping forward and backwards in the 3-member response sequence. Response rates in both RA and P were suppressed by NMDA. Pb-exposure potentiated the accuracy-impairing effects of NMDA by further increasing the frequencies of these error classes, and likewise potentiated the rate-suppressing effects of NMDA. These findings add further support to the possible involvement of Pb with the NMDA receptor complex.

Animals↗
PubMedDate not supplied

Acute trimethyltin exposure produces nonspecific effects on learning in rats working under a multiple repeated acquisition and performance schedule.

Previous research has explored the adverse effects of trimethyltin (TMT) on learning and memory in laboratory animals. Virtually all studies of TMT effects on learning have not, however, included appropriate controls to establish a selective effect on learning. This experiment investigated the effects of TMT on the repeated acquisition (learning) and performance of response sequences. Adult male Long-Evans rats, maintained at 300 g b.wt., were trained with food reinforcement under a multiple repeated acquisition (RA) and performance (P) schedule. The RA component required rats to learn a different three-member response sequence during each session (Center Right Left, RLC, RCL, LCR, or LRC); the correct response sequence remained constant in the P component (CLR). RA and P components alternated twice during a session. Rats were given 0, 4, or 8 mg/kg TMT IV after 30 sessions of stable baseline performance, and an additional 40 sessions were conducted following TMT. Prior to TMT, all groups maintained comparable accuracy levels in both RA and P components. Following TMT, significant decreases in both accuracy and response rate were obtained in the 8 mg/kg group. Thereafter, response rate and accuracy both recovered to near baseline levels, although large individual differences were observed. No selective effects of TMT were obtained on RA when compared to P. These data suggest that TMT-induced impairments on learning may be due to a generalized performance decrement rather than a specific effect on learning.

Animals↗
PubMedDate not supplied

Acquisition, steady-state performance, and the effects of trimethyltin on the operant behavior and hippocampal GFAP of Long-Evans and Fischer 344 rats.

Strain differences represent an overlooked variable that may play an important role in neurotoxic outcomes that can impact regulatory decision making. Here, we examined the strain-dependent effects of trimethyltin (TMT), a compound used as a positive control for behavioral and neurochemical assessments of neurotoxicity. Adult male Long-Evans (LE) and Fischer 344 (F344) rats (n=12 each) were trained to respond under a multiple, fixed-interval 3-min fixed-ratio 10-response (multi FI 3-min FR10) schedule of milk reinforcement. Acquisition was characterized by time-dependent changes in several behavioral endpoints in both strains, although rate of acquisition of the fixed-interval pattern of responding was slower in F344 rats. Steady-state (baseline) performance was characterized by slower overall rates of responding in F344 rats. There was little evidence of strain differences in many of the other baseline performance measures. Rats of each strain were then divided into two equal groups that received either 1 ml/kg saline or 8.0 mg/kg iv TMT approximately 18 h before the next test session. TMT produced transient changes in the performance of LE and F344 rats that lasted for several sessions. For many behavioral measures, F344 rats were more affected by TMT than were LE rats. TMT-induced reactive gliosis, as assessed by assaying glial fibrillary acidic protein (GFAP), was also greater in F344 rats than in LE rats. These results suggest F344 rats may be more susceptible to TMT-induced neurotoxicity than are LE rats.

Animals↗
PubMedDate not supplied

The nuclear lamina is a meshwork of intermediate-type filaments.

The nuclear lamina, a protein meshwork lining the nucleoplasmic surface of the inner nuclear membrane, is thought to provide a framework for organizing nuclear envelope structure and an anchoring site at the nuclear periphery for interphase chromatin. In several higher eukaryotic cells, the lamina appears to be a polymer comprised mainly of one to three immunologically related polypeptides of relative molecular mass (Mr) 60,000-75,000 (60-70K) termed lamins. Three lamins (A, B, and C) are typically present in mammalian somatic cells. Previous studies on nuclear envelopes of rat liver and Xenopus oocytes suggested that the lamina has a fibrillar or filamentous substructure. Interestingly, protein sequences recently deduced for human lamins A and C from complementary DNA clones indicate that both of these polypeptides contain a region of approximately 350 amino acids very similar in sequence to the coiled-coil alpha-helical rod domain that characterizes all intermediate-type filament (IF) proteins. Here we analyse the supramolecular organization of the native nuclear lamina and the structure and assembly properties of purified lamins, and show that the lamins constitute a previously unrecognized class of IF polypeptides.

Animals↗
PubMedDate not supplied

A case study in assessing an ethnically diverse community-based aging population: a multimethod approach.

Obtaining useful information to improve services for older, multi-ethnic populations requires a nontraditional approach to assessing needs that can overcome both cultural barriers and natural suspicions about research. This case study describes a multimethod needs assessment conducted in a large senior housing facility, where 58% of residents were non-English-speaking. Methods of data collection were both qualitative and quantitative. Data were gathered by focus groups, interviews, and a written survey (N = 874) on topics of need for personal care assistance, level of assistance required for instrumental activities of daily living, and mobility. Qualitative inquiry yielded information about facilities and safety, and culturally specific needs, particularly communication. The case study concludes by discussing how the research findings translated into on-site programmatic changes, and delineating the factors that contributed to the success of this approach.

Activities of Daily Living↗
PubMedDate not supplied

New strategies in nonantibiotic treatment of gram-negative sepsis.

Gram-negative bacterial infections are difficult to control and often lead to septic shock or septic syndrome. Many physiologic changes in sepsis are due to bacterial triggering of host responses. Improved understanding of these mechanisms has led to new treatment modalities that aim to block the runaway inflammatory process of sepsis. New therapeutic agents are currently being evaluated in animal and human studies. By combining these advances with adequate antibiotic therapy, it may be possible to improve overall survival in patients with gram-negative sepsis.

Animals↗
PubMedDate not supplied

The effects of lead exposure on learning in a multiple repeated acquisition and performance schedule.

This study sought to determine the selectivity of Pb-induced changes in learning, as distinct from non-specific or performance effects, and to explore the nature of the underlying error patterns contributing to any learning deficits. To accomplish this, rats were chronically exposed to 0, 50, or 250 ppm Pb acetate in drinking water from weaning and trained on a multiple repeated acquisition (RA) and performance (P) schedule beginning at 55 days of age. The RA component required the rat to learn a new 3-member sequence of responses during each experimental session (Center Right Left, RLC, CLR, RCL, and LRC), while the correct sequence of responses for the P component was constant across sessions (LCR). Significant decrements in accuracy on the RA component but not on the P component were found in Pb-exposed groups compared to control, effects that could not be attributed to differential rates of responding. Analyses of error patterns revealed that the effects of Pb exposure on RA accuracy levels derived from two sources. The first consisted of a perseveration of P-like sequence responding (LCR) even during the RA component. Secondly, Pb exposure increased perseverative responding on a single lever, even though the schedule itself never directly reinforced such repetitive responding. The increase in frequency of these two types of perseverative behavior was incompatible with acquisition of non P-like sequences during the RA component. Adding a 5 sec tone to the light stimuli signalling the transition between RA and P components of the multiple schedule failed to attenuate these effects of Pb, suggesting that deficits in stimulus control were not the sole behavioral mechanism of these impairments. Examination of individual data revealed the presence of both 'learners' and 'non-learners' in each group, with the prevalence of the latter being suggestively higher in Pb-exposed groups than in controls. These findings may be relevant to the classroom setting, where periods requiring learning may frequently be interspersed with periods of performance of learned skills.

Animals↗