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Biomedical subjects

J Beck

Publications and source records attributed to J Beck.

At least 253 records · Page 14Linked to original sources
PubMed1982

The effect of medial amygdala lesions on instrumental sexual responses in male rats.

In male rats bar press responses reinforced by the contact with estrous females were established during the preoperative training. Bilateral electrolytic lesions of the medial amygdala nuclei caused an impairment of copulatory behavior manifested by the appearance, during male-female contacts, of exploratory behavior or body investigation instead of copulatory behavior. In all subjects such noncopulatory contacts occurred alternately with those when the copulations took place. The latencies of instrumental responses immediately following the contacts during which intromissions took place remained unchanged. It is suggested that the medial amygdala exerts excitatory and regulatory influences on sexual arousal mechanisms in male rats.

Amygdala↗
PubMed1981

Low temperature excitation and emission spectroscopy of the photosynthetic bacteria Rhodopseudomonas sphaeroides 'wild-type' strain ATCC 17023.

Prompt and delayed emission of Rhodopseudomonas sphaeroides 'wild-type' strain ATCC 17023 was measured in the spectral range 550-950 nm at 1.7 K. The broad emission spectra could be resolved into separate bands by excitation spectroscopy. Through a comparison of the separated excitation and emission spectra of the present study with absorption and fluorescence spectra of photosynthetic pigments given in the literature, the emitting species could be identified. Beside the well-known pigments bacteriochlorophyll (BChl), bacteriopheophytin (BPh) and carotenoids, additional pigments could be detected. In the visible and near-infrared range, the fluorescence of pigments could be observed which were produced by the biosynthesis of BChl in the cells. Further, fluorescence bands at 753 and 813 nm are interpreted as originating from BPh (F-753) and BChl (F-813). Delayed emission signals between 700 and 800 nm were attributed to a metalloporphyrin phosphorescence. Surprisingly, the excitation spectra of the delayed BChl emissions measured at 872 and 912 nm showed the same excitation spectra as the short-wavelength emission, typical of metalloporphyrins. This is strong indication of an energy transfer between metalloporphyrins and BChl.

Bacteriochlorophylls↗
PubMed1981

Optically excited triplet states in the bacteria Rhodopseudomonas sphaeroides 'wild-type' detected by magnetic resonance in zero-field.

Optically-detected magnetic resonance (ODMR) experiments in zero-field on the photosynthetic bacteria Rhodopseudomonas sphaeroides revealed triplet states belonging to molecules which have a prompt emission in the optical region from 590 to 700 nm and a delayed emission between 700 and 830 nm. The zero-field parameters of these triplet states are 29 less than [D] less than 34 . 10(-3) cm-1 and 4 less than [E] less than 8 . 10(-3) cm-1, the decay rates of the [D] + [E] transitions being in the order of 60-340 ms. The correlation between optical emission and radio-frequency was used to separate the total optical emission from 590-700 nm into individual emissions, belonging to molecules whose triplet states were studied by ODMR in this region. Comparing the fluorescence microwave double resonance (FMDR) spectra with the results of excitation spectroscopy, as well as comparing the zero-field parameters and the decay rates with that of Mg-porphyrins in matrices given in the literature, allowed the identification of the emitting molecules as Mg-porphyrins which are produced by the biosynthesis of bacteriochlorophyll in the cells.

Magnetics↗
PubMed1981

[Changes in the water and electrolyte contents of human erythrocytes due to Visotrast 370 during I-V urography (author's transl)].

The effect of the contrast medium Visotrast 370 on the water content and volume of erythrocytes, and on the electrolyte levels of plasma and erythrocytes during I-V urography was examined. The measurements were carried out at one, ten and 30 minutes after injection. One minute after injection there was a significant reduction in the water content and volume of the erythrocytes. The levels of sodium and potassium ions in the plasma were reduced ten minutes after contrast injection, but increased in the erythrocytes. After 30 minutes, significant changes could no longer be demonstrated. Possible causes for these changes and their effects on other organs are discussed. Certain practical conclusions are drawn.

Calcium↗
PubMed1981

Human hematopoietic tumors in nude mice.

Despite the difficulty in establishing human hematopoietic tumors in nude mice, four human lymphomas were successfully heterotransplanted and passaged serially in our laboratory. Additional immunosuppression with chemotherapy, whole-body radiation or splenectomy was not required for establishment of these tumors. All four of these tumors were of the non-Hodgkin's lymphoma type. In each case the tumors in the nude mice were histologically identical to the biopsy specimens from the patient in whom they were derived. Attempts to transplant tumor from 17 patients with Hodgkin's disease or 4 patients with immunoblastic lymphadenopathy were unsuccessful. Tumors from 2 patients with chronic myelogenous leukemia and 1 with hairy cell leukemia could be grown in nude mice conditioned with whole-body radiation or cytosine arabinoside, but these tumors could not be passaged to other nude mice. Cell surface markers were determined on the four serially passaged lymphomas. These surface markers were similar to the markers on the original tumors, even after long periods of mouse-to-mouse passage. In 1 patient with fevers, night sweats and mediastinal mass in whom a diagnosis had not been made after several biopsies, examination of tumor tissue that had been transplanted from the patient to the nude mouse clearly established the diagnosis of lymphoma.

Animals↗
PubMed1981

The influence of changes of partners on the integration of the male-female set in rats.

Instrumental sexual responses were tested in two group; of rats. In Group 1 the subjects were tested with the same partners throughout the whole experiment, whereas in Group 2 the partners were changed every second week of experiment. The statistically significant positive correlations between the male and female response latencies were observed significantly more often in Group 1 than in Group 2, but only if the female partners were in estrous stage. It is suggested that mating with the same partner enhanced the degree of integration of the male-female set in rats.

Animals↗
PubMed1980

The future need for geriatric manpower in the United States.

Additional medical manpower will be required to meet the growth in the elderly segment of the United States population over the next 50 years. This paper provides estimates of the needs for medical geriatric manpower under four different models: continuation of the status quo; academic geriatricians only; provision of care by academic and consultant geriatricians; and provision of care by academic, consultant, and primary-care geriatric practitioners. Each option is further analyzed in terms of three levels of delegation to nonphysician clinicians. We project the implications of these 12 patterns through the year 2030, assuming present usage levels and allowing for improved care of the elderly. The need for geropsychiatric care is explored separately. We think that geriatricians should provide improved care, including both consultant and primary care, to people aged 75 years and older, and that they should delegate a moderate amount of responsibility to nurse practitioners, physician assistants, and social workers. On the basis of these assumptions, and allowing for an academic role as well, we estimate that the United States will require between 7000 and 10,300 geriatricians by the year 1990; the best intermediate figure is about 8000.

Aged↗
PubMed1980

Interferon production in cocultures between mouse spleen cells and tumor cells: possible role of mycoplasmas in interferon induction.

Interferon production was measured in the murine mixed lymphocyte tumor cell interaction (MLTI) using spleen cells of three inbred mouse strains and a number of in vitro grown lymphoma cells. No difference in interferon production was observed when syngeneic or allogeneic combinations were compared. Interferon was not detectable during the first 6 h of culture and reached its maximum after 12--24 h. In contrast, natural killer cell activity of spleen cells against one of these lymphoma lines (YAC-1) was already high after 4h. A cell line that was not susceptible to natural killing (MDAY-D2) induced the same amount of interferon as YAC-1. These findings suggest that natural killer cell activity and interferon induction in the MLTI are not correlated. Several lymphoma cell lines induced interferon in the MLTI whereas some others did not. All lines that were inductive were found to contain mycoplasmas. Furthermore, even the cell-free supernatants of inducing lines contained mycoplasmas and induced interferon. Purified mycoplasmas and membranes thereof were able to induce interferon production in mouse spleen cells. Our data strongly suggest that interferon production in the MLTI is caused by mycoplasmas. This artifact is the relevance for three reasons. First, cocultures between lymphoma cells and lymphocytes are widely studied in immunology. Secondly, contamination with mycoplasmas is extremely common and often goes unnoticed in immunological laboratories. Thirdly, interferon is known to affect profoundly a number of in vitro functions of immunocompetent cells.

Animals↗
PubMed1980

The integration of the male-female set studied by simultaneous investigation of the instrumental sexual responses in rats.

Instrumental sexual responses were investigated under conditions that the contact between the subjects was possible when both of them had accomplished the instrumental response. The instrumental responses were studied in three situations: (i) when the female subjects were in induced estrus, (ii) when they were in natural estrus, and (iii) in natural diestrus. The correlation between the male and female response latencies was estimated for all sessions. The significant positive correlation was in about 40 percent of sessions in both estrus situations and only in 4 percent in the diestrus situation. The distribution of the correlation coefficients was similar in both estrus situations. In diestrus situation the positive correlation was less often observed then in estrus situations, yet it differed significantly from random distribution. It is concluded that the correlation between male and female response latencies could be used as an indicator of the degree of integration of the male-female set.

Animals↗