Estimating ON and OFF contributions to the photopic hill: normative data and clinical applications.

BACKGROUND: With progressively brighter stimuli, the amplitude of the b-wave of the human photopic electroretinogram (ERG) first increases to a maximal value (Vmax) and then decreases to finally reach a plateau, a phenomenon known as the photopic hill (PH). A mathematical model combining a Gaussian (G) and a logistic (L) growth function was previously proposed to fit this unusual luminance-response curve, where the G and L functions were suggested to represent, respectively, the OFF and ON retinal pathway contributions to the building of the PH. METHOD: The PHs of patients presenting stationary diseases affecting specifically the ON (3 CSNB-1) or OFF (4 CPCPA) retinal pathways as well as patients affected with retinitis pigmentosa (14 RP) of different stages or etiology were analyzed using this mathematical model and compared to the PHs of a group of 28 normal subjects. RESULTS: The PH of the CSNB-1 patients had a much larger contribution from the G function compared to normal subjects, whereas the opposite was observed for the CPCPA patients. On the other hand, analysis of data from RP patients revealed variable G-L contributions to the building of their PH. CONCLUSION: In this study, we confirm the previous claim that the luminance-response function of the photopic ERG b-wave can be decomposed into a Gaussian function and a logistic growth function representing, respectively, the OFF and ON retinal pathways. Furthermore, our findings suggest that this mathematical decomposition could be useful to further segregate and potentially follow the progression of retinopathies such as RP.

Postnatal hyperoxia and the developing rat retina: beyond the obvious vasculopathy.

Although a great deal of emphasis has been placed on the vasculopathy that is associated with oxygen-induced retinopathy (OIR), our studies also revealed significant and irreversible structural (retinal histology) and functional (scotopic and photopic electroretinograms) impairments that were significantly more severe in pigmented Long-Evans rats compared to the more commonly used albino Sprague Dawley rats. In the following pages, we will highlight what we have learned about the retinal pathophysiological processes of OIR taking place in strains of both rats with the hope that this will trigger investigations into new therapeutic strategies to complement those geared at preventing the vasculopathy.

The effect of oxygen and light on the structure and function of the neonatal rat retina.

The neonatal rat is born with its eyes closed and an immature visual system, that some say is equivalent to that of a human fetus at 26 weeks of gestation. From birth, the visual system of the newborn rat will gradually mature, the first manifestation of that being the opening of the eye which usually take place at postnatal day 14. Complete maturation of the retina and visual pathways is normally reached at the end of the first month of life. The neonatal rat model thus represents a unique paradigm to study the normal and abnormal maturation of the primary visual pathways that normally occurs in utero in human subjects. Our laboratory has, over the past decade, developed two animal models of postnatally induced retinopathy, namely the Oxygen-Induced Retinopathy (OIR) that share several common features with the human Retinopathy of Prematurity (ROP) and the Light-Induced Retinopathy that is viewed by some as a valid model of some forms of Retinitis Pigmentosa (RP). The following pages review what is known of the pathophysiological processes taking place and suggest possible therapeutic avenues that could be explored in order to halt the degenerative process.

[Early application of plasmapheresis for complex treatment of purulent mediastinitis].

Acute purulent mediastinitis (APM) is one of the most difficult forms of surgical infection with severe clinical course and lethality from 17 to 80%. Overall 80 patients with APM were treated; plasmapheresis in postoperative period was used at 66 of them. The main criteria of negative prognosis at the patients with APM were elderly age, high score on APACHE-2, SAPS-2 and SOFA scales, higher level of creatinine and urea serum concentration, hyperglycemia, leucopenia. Early application of plasmapheresis was associated with lower lethality (12.5% at the group with early beginning of plasmapheresis, 35.3% at the group with late beginning, 36.2% at the control group). Plasmapheresis promotes normalization of hemostasis, microcirculation and immune parameters, reduction of intoxication and systemic inflammation syndrome.

[Lung perfusion scanning in the comprehensive diagnosis of pulmonary thromboembolism].

The aim of the study was to define the sensitivity, specificity, and diagnostic accuracy of lung perfusion scanning (LPS) in pulmonary thromboembolism (PTE). PTE diagnostic techniques are comparatively assessed. The data on 108 patients with suspected PTE and lung perfusion defects revealed at pulmonary scintigraphy were analyzed. The diagnostic techniques included electrocardiography (ECG), 150 echocardiography, venous ultrasonography, chest X-ray, and LPS. The significant signs of PTE were singled out of 150 ones (history data, complaints, clinical symptoms, instrumental findings, autopsy data); LPS data were analyzed in detail. The sensitivity, specificity, and accuracy of LPS were 95.2, 20, and 77.7%, respectively. It is shown that lung scans should be interpreted, by taking into account X-ray data, and LPS should follow ECG, venous ultrasonography, and chest X-ray.

[Possibility of using microbiological data in epidemiological analysis of hospital pneumonias]. / Vozmozhnosti ispol'zovaniia mikrobiologicheskikh dannykh pri épidemiologicheskom analize vnutribol'nichnykh pnevmonii.

A total of 528 patients with nosocomial pneumonias were examined by bacteriological methods during 4 years. The data on the patients and on 2468 bacterial strains isolated from them were computer processed using original software "Hospital Infection". Special attention was paid to hospital strains of pneumonia agents of the same taxonomic position with identical markers of antibacterial resistance. Tendencies and seasonal fluctuations in the prevalence of hospital serovars were detected. Special bacteriological studies helped detect differences in the translocation capacity of different biological variants of the agents. Routine bacteriological studies and their adequate statistical computer processing yield information needed for epidemiological analysis of the development of nosocomial pneumonias in patients of clinical wards of different profile.

Structure of the ankyrin-binding domain of alpha-Na,K-ATPase.

The ankyrin 33-residue repeating motif, an L-shaped structure with protruding beta-hairpin tips, mediates specific macromolecular interactions with cytoskeletal, membrane, and regulatory proteins. The association between ankyrin and alpha-Na,K-ATPase, a ubiquitous membrane protein critical to vectorial transport of ions and nutrients, is required to assemble and stabilize Na,K-ATPase at the plasma membrane. alpha-Na,K-ATPase binds both red cell ankyrin (AnkR, a product of the ANK1 gene) and Madin-Darby canine kidney cell ankyrin (AnkG, a product of the ANK3 gene) utilizing residues 142-166 (SYYQEAKSSKIMESFK NMVPQQALV) in its second cytoplasmic domain. Fusion peptides of glutathione S-transferase incorporating these 25 amino acids bind specifically to purified ankyrin (Kd = 118 +/- 50 nM). The three-dimensional structure (2.6 A) of this minimal ankyrin-binding motif, crystallized as the fusion protein, reveals a 7-residue loop with one charged hydrophilic face capping a double beta-strand. Comparison with ankyrin-binding sequences in p53, CD44, neurofascin/L1, and the inositol 1,4,5-trisphosphate receptor suggests that the valency and specificity of ankyrin binding is achieved by the interaction of 5-7-residue surface loops with the beta-hairpin tips of multiple ankyrin repeat units.

[Problems in improvement of work conditions in railroad transport]. / Problemy uluchsheniia uslovii truda na podvizhnom sostave i putevoi tekhnike.

Within a short period of time the temperature conditions have been improved at working places of locomotive drivers and their assistants, a new switchboard for locomotives developed, noise and vibration in cabins were reduced, etc. Hygienic problems associated with improvement of locomotives are supervised by the Ministry of Communications and by special commissions.

[Sanitary-hygienic regulations of the utilization of asbestos production waste in railway facilities]. / Sanitarno-gigienicheskaia reglamentatsiia ispol'zovaniia otkhodov asbestovogo proizvodstva v putevom khoziaistve.

The hazards of utilizing the asbestos production wastes in railway construction are analyzed. An increased risk of cancer development was observed only in groups exposed to asbestos in concentrations surpassing the maximal permissible level, as shown by mortality records. The authors come to a conclusion that the use of asbestos waste is permissible only on condition of strict adherence to sanitary regulations.

[Reasons for privileges for hard and hazardous work conditions in railway transport]. / Voprosy obosnovaniia l'got za tiazhelye i vrednye usloviia truda dlia professii zheleznodorozhnogo transporta.

Many railway occupations have special work conditions which considerably depend on peculiarities of work and therefore could not undergo hygienic regulation. The article gives examples of such occupations connected mostly with personal risk in railway traffic, marked work hardness, etc. Reasonable privileges and compensations are established for those occupations.

DSM-III-R personality disorders in parents of schizophrenic patients.

This study examines the frequency of DSM-III-R personality disorders in parents of 58 patients who were admitted consecutively to a New York State psychiatric hospital with a first admission for a schizophrenia-like psychosis. For comparison, a control group of 65 families were randomly recruited who were in the same age group and denied any psychiatric history in their immediate families. Significantly more parents of the patients had a diagnosed personality disorder than controls. These were classified as schizoid, schizotypal, histrionic, and sadistic types by DSM-III-R criteria. While paranoid personality disorder was frequent, it was equally distributed among both groups of parents. These data suggest that the genetic boundaries to a "schizophrenia spectrum" disorder may extend further than previously thought and particularly the specific characteristics that are common to a wide variety of these disorders need to be examined in further analyses.

Familial thyroid disease and delayed language development in first admission patients with schizophrenia.

One hundred consecutive first admission patients with a DSM-III-R diagnosis of schizophrenia, schizoaffective disorder, or schizophreniform disorder were compared with 100 randomly selected community controls. Childhood histories of physical, medical, and perinatal trauma, as well as physical and cognitive development, were examined by structured interviews with all available mothers of patients and controls. The prevalence of specific psychiatric disorders and several medical illnesses among first degree and more distant relatives was determined by family history questionnaires. The patient group did not have an excess of childhood head injuries, serious infections, or perinatal/birth complications compared with controls. With social class level taken into account, it was found that the acquisition of reading skills occurred significantly later in patients than controls. Family histories of schizophrenia and thyroid disorders were significantly more frequent among patients than controls. These data fail to indicate any childhood physical or medical environmental trauma that could lead to an increased risk for schizophrenia, although patients were substance abusers to a greater extent than controls. This study also confirms the already known contribution of familial factors and suggests an association of the inheritance of thyroid disorders with schizophrenia. Delayed development of reading skills suggests that precursers of illness may appear early in life before psychosis is evident.