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Biomedical subjects

J Cohen

Publications and source records attributed to J Cohen.

At least 487 records · Page 27Linked to original sources
PubMed1997

Three-dimensional structural analysis of recombinant rotavirus-like particles with intact and amino-terminal-deleted VP2: implications for the architecture of the VP2 capsid layer.

Rotaviruses are the leading cause of severe infantile gastroenteritis worldwide. These viruses are large, complex icosahedral particles consisting of three concentric capsid layers enclosing a genome of eleven segments of double-stranded RNA (dsRNA). The amino terminus of the innermost capsid protein VP2 possesses a nonspecific single-stranded RNA and dsRNA binding activity, and the amino terminus is also essential for the incorporation of the polymerase enzyme VP1 and guanylyltransferase VP3 into the core of the virion. Biochemical and structural studies have suggested that VP2, and especially the amino terminus, appears to act as a scaffold for proper assembly of the components of the viral core. To locate the amino terminus of VP2 within the core, we have used electron cryomicroscopy and image reconstruction to determine the three-dimensional structures of recombinant virus-like particles that contain either full-length or amino-terminal-deleted forms of VP2 coexpressed with the intermediate capsid protein VP6. A comparison of these structures indicates two significant changes along the inner surface of VP2 in the structure lacking the amino terminus: a loss of mass adjacent to the fivefold axes and a redistribution of mass along the fivefold axes. Examination of the VP2 layer suggests that the proteins are arranged as dimers of 120 quasi-equivalent molecules, with each dimer extending between neighboring fivefold axes. Our results indicate that the amino termini of both quasi-equivalent VP2 molecules are located near the icosahedral vertices.

Animals↗
PubMed1997

Two proline residues are essential in the calcium-binding activity of rotavirus VP7 outer capsid protein.

Rotavirus maturation and stability of the outer capsid are calcium-dependent processes. It has been shown previously that the concentration of Ca2+-solubilizing outer capsid proteins from rotavirus particles is dependent on the virus strain. This property of viral particles has been associated with the gene coding for VP7 (gene 9). In this study the correlation between VP7 and resistance to low [Ca2+] was confirmed by analyzing the origin of gene 9 from reassortant viruses prepared under the selective pressure of low [Ca2+]. After chemical mutagenesis, we selected mutant viruses of the bovine strain RF that are more resistant to low [Ca2+]. The genes coding for the VP7 proteins of these independent mutants have been sequenced. Sequence analysis confirmed that these mutants are independent and revealed that all mutant VP7 proteins have proline 75 changed to leucine and have an outer capsid that solubilized at low [Ca2+]. The mutation of proline 279 to serine is found in all but two mutants. The phenotype of mutants having a single proline change can be distinguished from the phenotype of mutants having two proline changes. Sequence analysis showed that position 75 is in a region (amino acids 65 to 78) of great variability and that proline 75 is present in most of the bovine strains. In contrast, proline 279 is in a conserved region and is conserved in all the VP7 sequences in data banks. This region is rich in oxygenated residues that are correctly allocated in the metal-coordinating positions of the Ca2+-binding EF-hand structure pattern, suggesting that this region is important in the Ca2+ binding of VP7.

Amino Acid Sequence↗
PubMed1997

The PsyScope experiment-building system.

PsyScope is a system for building behavioral experiments on the Apple Macintosh computer using a graphic user interface that requires no computer programming. The program supports a wide variety of experimental designs, multimedia formats, and stimulus control. A freeware version is available at the author's web site.

Computer Communication Networks↗
PubMed1997

School-related issues among HIV-infected children.

OBJECTIVE: Many children with human immunodeficiency virus (HIV) infection are surviving long enough to reach school age. This study describes issues related to school attendance and disclosure of HIV infection in a population of HIV-infected children. METHODS: A statewide pediatric HIV surveillance system was used to collect data on school-age (>/=5 years old) HIV-infected children. In addition, HIV clinic nurses familiar with the child's history participated in a cross-sectional survey that collected information on school-related issues during the 1993-1994 school year. RESULTS: Of the 92 school-age children, only 3 were too ill to attend school. Another 5 children were home-schooled. Of the 84 who attended school outside the home, 25% had severe symptoms of HIV infection (Centers for Disease Control and Prevention [CDC] clinical category C). Absence from school ranged from less than 2 weeks during the year for half of the children (51%) to more than 8 weeks for 9 children (12%). Twenty-nine percent of the children received medication in school, usually administered by the school nurse. Over two thirds of the 50 children ages 5 to 10 years had not been told that they had HIV infection. Only 1 of the 20 children more than 10 years of age was not aware of her HIV infection. For 53% of the children attending school, no school personnel had been informed of the child's HIV infection. Administration of HIV medications at school, age of child, and treatment at one particular HIV clinic were associated with the parents' decision to inform school personnel. In the 47% of cases where the school had been informed, school nurses were most frequently notified, followed by principals and teachers. CONCLUSION: Only 3% of school-age children were too ill to attend school, and almost all were enrolled in public schools. The number of HIV-infected children reaching school age will continue to grow, and public schools will bear the responsibility for educating these children. Health care providers will increasingly be called upon for guidance by both educators and families to assure that HIV-infected children receive the best education possible.

Absenteeism↗
PubMed1997

Transscleral diode laser cyclophotocoagulation on autopsy eyes with abnormally thinned sclera.

BACKGROUND AND OBJECTIVE: To determine, using autopsy eyes, whether diode laser energy adjustments are indicated in patients with thin sclera. MATERIALS AND METHODS: In the laboratory, the superior 180 degrees of sclera at the limbus was dissected to the level of barely visible anterior uvea and the opposite 180 degrees of sclera served as the control in three human cadaver eyes. A contact G-probe was placed at the limbus, and settings of a diode laser were increased in increments from 1.0 to 9.0 J at 4 burns per setting in each location. RESULTS: On gross examination, circular hypopigmented lesions were seen in the ciliary body (CB) beginning at 3.0 J in thin sclera and at 5.0 J in normal sclera. On light microscopic examination of thin scleral sections, CB damage began at 2.9 J and CB/ciliary body epithelium (CBE) damage occurred beginning at 3.5 J. In normal sclera, minimal CB/CBE changes occurred at 6.0 to 7.5 J. No scleral damage was visible in either the experimental or the control groups. CONCLUSION: Cycloablation energy adjustments are indicated on eyes with abnormally thin sclera to achieve similar histologic end points using the diode laser.

Basement Membrane↗
PubMed1997

Spectacle/loupe telescope designed for reading music.

BACKGROUND: The optical needs of most low-vision patients can be satisfied with one or more of a large array of prefabricated, off-the-shelf, handheld or spectacle-mounted devices. When these devices do not provide the expected or desired results, a practitioner has the opportunity to design a custom-made device to satisfy the vision demands of the patient. CASE REPORT: A patient with a history of having tried several devices to see his music while playing the violin was examined and a simple, inexpensive. Galilean telescopic device was formulated, designed, and constructed. The objective was to create a telescope that would provide adequate magnification with a wider field of view than was available with prefabricated devices. The components needed to generate the required magnification were determined using basic telescope design concepts and equations. CONCLUSIONS: For patients with intermediate and/or distance symptoms testing with a telescope is an important part of the low-vision evaluation. Field of view, expense, and the time required to obtain the device are important considerations in deciding what to prescribe. The pathology involved, task demands, time since onset of decreased acuity, and personality of the patient will dictate, to a large degree, the acceptance of the device.

Eyeglasses↗
PubMed1997

Child and adolescent psychoanalysis: research, practice and theory.

In the last fifteen years, there have been three major developments in child and adolescent psychoanalysis and psychoanalytically informed psychotherapy. After briefly reviewing what is clear and unclear about the nature of child psychoanalysis, the author describes and critiques three recent trends: (1) a greater differentiation of aetiological factors that involves an enhanced understanding about developmental influences and how they may be utilised therapeutically; (2) a shift in child analytic theory to a more equitable balance between internal and external factors, with more attention being paid to the external; and (3) a significant increase in the psychoanalytically informed, empirical study of development as well as the process and outcome of treatment. Changes in these three overlapping domains are examined and their relevance to clinical practice discussed. It is suggested that the increase in the systematic and empirical study of the child psychoanalytic process has been the most significant recent development in the field; it is this that has the greatest potential to minimise rhetoric, to support discovery and to clarify what is unique about psychoanalytically informed work with children and adolescents.

Adolescent↗
PubMed1997

Cholera and typhoid vaccine. The current state of play.

The field of travel medicine is undergoing rapid change. Vaccination recommendations change with disease outbreaks, emerging infections and the availability of new vaccines. The following information on typhoid and cholera vaccination should be used in conjunction with up to date information and individualised for each traveller. It is emphasised that vaccination forms just part of the pretravel health consultation and does not replace the need for appropriate preventive advice and information.

Adolescent↗
PubMed1997

[Comparative randomized controlled study between human follicle- stimulating hormone (FSH-HP) and human menopausal gonadotropins (hMG) in in vitro fertilization].

We present the results of a prospective randomized trial comparing the issue of IVF-ET and of ICSI when either highly purified human folliculostimulin (FSH-HP) or human menopausal gonadotrophin (hMG) is used. There seems to be a trend to a better rate of ongoing pregnancies when FSH-HP is used although not statistically significant. The study has been stopped due to the lack of hMG.

Adult↗
PubMed1997

[Review of the latest treatments of vulvovaginal mycoses: role of fenticonazole nitrate (Lomexin) in their treatment].

Candidal vulvovaginitis result from the deficiency of hort defense mechanisms in front of the activity factors of candida. Filamentation and then adhesion of candida to vaginal mucosa is the most important step in the process of infection. The principal virulence factors of candida are its genotypical and phenotypical instability as well as proteinase secretion facilitating adhesion and vaginal mucosa invading. Hort defense mechanisms are essentially constituted by vaginal flora and local cellular immunity. A weakening even moderate of this immunity can favor the spontaneous transformation from asymptomatic colonization to symptomatic vaginitis. The most utilized treatments are imidazol derivates in short courses. The fenticonazole nitrate has the particularity and the recently discovered advantage over the other agents available in single dose regimen to inhihate in vitro the proteinase secretion in a dose dependent manner. The different clinical studies carried out in comparative or non comparative studies have demonstrated its efficiency and tolerance. The most recent studies stress the swiftness of symptoms disappearance.

Antifungal Agents↗