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Biomedical subjects

S Malkin

Publications and source records attributed to S Malkin.

At least 55 records · Page 3Linked to original sources
PubMed1978

Fractures of the hip: a three-year survey in one hospital, including experience with the Pugh nail procedure.

Records were reviewed on 445 patients with fracture of the hip admitted to St. Paul's Hospital, Vancouver, Canada, during the period 1973--1975 inclusive. The epidemiologic factors were analyzed: age, sex, where and when the accident occurred, site of the fracture, the treatment procedure, length of time in hospital, complications, associated conditions, and final placement of the patient. Of the patients, 286 (64 percent) were more than 70 years of age. Among the 260 causal accidents in the patients' home living space or in the hospital, 35 involved toileting. The great majority of the fractured hips (330) were treated by open operation and internal fixation with the Pugh nail; the remainder were treated by conservative methods, various other devices, or arthroplasty. Within 30 days, 121 patients were discharged to their own homes and 68 to a major rehabilitation hospital. A total of 289 patients eventually returned to their own homes. The Pugh nail method of fixation permits early physiotherapy and early walking exercises, beginning within the first few days postoperatively. This largely accounts for the low complication rate, rapid achievement of functional status, and reduced hospital stay. Among the 445 patients there were 43 deaths, including 10 which occurred before operation could be undertaken.

Aged↗
PubMed1977

The effect of electron donors and acceptors on light-induced absorbance changes and photophosphorylation in Rhodospirillum rubrum chromatophores.

Light-induced difference spectra between 400 and 640 nm of Rhodospirillum rubrum chromatophores were performed in the presence and absence of exogenous electron donor/acceptor systems and compared with the chemical oxidation spectrum. The results indicate that the component previously defined as P430 is not a unique entity but rather represents different species, or a mixture of species, under various conditions. Under all conditions in which the reaction center bacteriochlorophyll is reversibly photooxidized, as indicated by the bleaching around 600 nm, it is also contributing to the absorbance increase around 430 nm. In one case, in presence of reduced dichloroindophenol and in the absence of oxygen, the photooxidation of reaction center bacteriochlorophyll is fully supressed. Under these conditions an irreversible change around 430 nm is still observed and seems to be due to the Soret band of b-type cytochrome. In the presence of reduced dichloroindophenol and absence of oxygen there is a marked inhibition of photophosphorylation. This inhibition is apparently due to the complete reduction of the cyclic electron carriers. Addition of the low potential dye benzyl viologen facilitates an almost complete recovery of the reversible photooxidation of reaction center bacteriochlorophyll as well as of photophosphorylation. These results indicate that the apparent mid-point potential of the primary electron acceptor in Rhodospirillum rubrum chromatophores is probably in the range of that of benzyl viologen (E'o = - 340 mV).

2,6-Dichloroindophenol↗
PubMed1977

The photochemical and fluorescence properties of whole cells, spheroplasts and spheroplast particles from the blue-green alga Phormidium luridum.

The photochemical activities and fluorescence properties of cells, spheroplasts and spheroplast particles from the blue-green alga Phormidium luridum were compared. The photochemical activities were measured in a whole range of wavelengths and expressed as quantum yield spectra (quantum yield vs. wavelength). The following reactions were measured. Photosynthesis (O2 evolution) in whole cells; Hill reaction (O2 evolution) with Fe(CN)63- and NADP as electron acceptors (Photosystem II and photosystem II + Photosystem I reactions); electron transfer from reduced 2,6-dichlorophenolindophenol to diquat (Photosystem I reaction). The fluorescence properties were emission spectra, quantum yield spectra and the induction pattern. On the basis of comparison between the quantum yield spectra and the pigments compositions the relative contribution of each pigment to each photosystem was estimated. In normal cells and spheroplasts it was found that Photosystem I (Photosystem II) contains about 90% (10%) of the chlorophyll a, 90% (10%) of the carotenoids and 15% (85%) of the phycocyanin. In spheroplast particles there is a reorganization of the pigments; they loose a certain fraction (about half) of the phycocyanin but the remaining phycocyanin attaches itself exclusively to Photosystem I (!). This is reflected by the loss of Photosystem II activity, a flat quantum yield vs. wavelength dependence and a loss of the fluorescence induction. The fluorescence quantum yield spectra conform qualitatively to the above conclusion. More quantitative estimation shows that only a fraction (20--40%) of the chlorophyll of Photosystem II is fluorescent. Total emission spectrum and the ratio of variable to constant fluorescence are in agreement with this conclusion. The fluorescence emission spectrum shows characteristic differences between the constant and variable components. The variable fluorescence comes exclusively from chlorophyll a; the constant fluorescence is contributed, in addition to chlorophyll a, by phycocyanine and an unidentified long wavelength component. The variable fluorescence does not change in the transition from whole cells to spheroplasts. However, the constant fluorescence increases considerably. This indicates the release of a small fraction of pigments from the photosynthetic photochemical apparatus which then become fluorescent.

Cyanobacteria↗
PubMed1977

Development of Photosystem II Activity in Chlamydomonas reinhardi Mutants: Insertion of Photosystem II Units into Inactive Preexisting Membranes versus Continuous Formation of New Photosynthetic Membranes.

In a previous work the development of photosystem II activity during the greening process of the y-1 mutant of Chlamydomonas reinhardi was studied (Cahen, Malkin, Shochat, Ohad. Plant Physiol 58: 257-267). Measurements of quantum yield, maximal rate of electron transfer, flash yield, and fluorescence induction indicated that photosystem II development consists of two partially overlapping phases: (a) reorganization and integration of preexisting units; and (b) addition of newly formed units to the growing membranes.In the present work an attempt was made to study these two processes independently. This was achieved using two experimental systems: (a) cells of the y-1 mutant, greened in the presence of chloramphenicol (CAP), whose activity is repaired under conditions which prevent further chlorophyll synthesis and membrane growth (dark or light with addition of cycloheximide [CHI]); (b) greening cells of a pale mutant derived from y-1 in which chloroplast membranes are formed gradually during several cell divisions.In both systems different parameters of 2,6-dichlorophenolindophenol reduction, as well as fluorescence, were measured. The results are interpreted using a kinetic model reported previously. It is concluded that during repair of photosynthetic activity in inactive membranes which were formed previously in the presence of chloramphenicol, photosystem II reaction centers are formed and integrated in preexisting membranes. In the pale green there is complete de novo synthesis of units of constant composition which are added during formation of new chloroplast membranes.

Journal Article↗
PubMed1976

Care of the terminally ill at home.

Care of the terminally ill at home demands the attention of the medical and paramedical community. Patients who choose to remain at home while death approaches must be given full physical, emotional and psychological support by the attending physician and home care services personnel. In 1974 the Vancouver early hospital discharge home care service provided such care to 47 patients. Generally both patient and family were happy with the program. A few families were unable to cope for more than a few days but most continued the care almost to the end, a large number (14) keeping the patient at home until death occurred. Added benefits are the lower costs and the freeing of hospital beds.

Adolescent↗
PubMed1976

Drilling of bone.

Explore the source record for details and available documents.

Biomechanical Phenomena↗
PubMed1976

Development of Photosystem II Complex during Greening of Chlamydomonas reinhardi y-1.

The relative content of organized pigment, active centers, and acceptor pools of photosystem II and their interconnection during the development of the photosynthetic membranes of Chlamydomonas reinhardi y-1 have been measured using the fluorescence induction technique. The degree of connectivity and efficiency of the developing system has been assessed also from measurements of maximal rates, quantum yield, and flash yield of 2,6-dichlorophenolindophenol photoreduction using H(2)O as the electron donor. The results obtained indicate that the process of membrane development in this organism consists of two phases: an initial phase of reorganization and connection between pre-existing components, and a second phase of actual accumulation of newly formed, complete, and active units. The ratio of active centers to Chl remains practically constant throughout the process while the degree of connectivity between the active center and the plastoquinone pool was doubled during the early phase of the greening. In addition the degree of connectivity between the plastoquinone pool and the rest of the electron transport chain increases as demonstrated by a 10- to 20-fold rise in the quantum yield and a 10-fold rise in the maximal rate and the flash yield. The ratio of light harvesting Chl to active centers remains apparently constant during the second phase of the greening as indicated by light saturation experiments and by the constancy of the apparent photosynthetic unit size. Electron donation from H(2)O seems to develop slower than the activity of the rest of the complex as demonstrated by measurements of 2,6-dichlorophenolindophenol photoreduction using 1,5-diphenylcarbazide as the electron donor. The value of all the above parameters which remain constant during the second phase of the greening are comparable to those obtained with membranes of light-grown cells.

Journal Article↗