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Biomedical subjects

M Kramer

Publications and source records attributed to M Kramer.

At least 199 records · Page 11Linked to original sources
PubMed1982

T cell-specific suppressor factor(s) with regulatory influence on interleukin 2 production and function.

In this study we report that alloantigen-activated spleen cells produce both amplifying and suppressive factors under the same conditions. Both types of soluble mediators--as detected in different assay systems--were present in the supernatants of in vivo sensitized and in vitro restimulated spleen cell populations and were separable by gel filtration. As shown by others, the amplifying factor (IL 2) was eluted in the size range of 30,000 m.w. The suppressive factor(s) (SF) was eluted in the size range of 10,000 m.w. SF was shown to inhibit the proliferative response of T cells to alloantigen, as well as the generation of regulatory T cells and cytotoxic T cells from their precursors when added at the beginning of the in vitro culture. Furthermore, SF inhibited the release of IL 2 from producer T cells but had no detectable effect on the interaction of IL 2 with receptive T cells. In addition it was shown that SF does not affect the generation of PFC from their precursors after activation by T cell-independent antigens. The results indicate that SF selectively acts on T cells and that it is involved in the regulation of the immune response by modulating early events in T cell activation.

Animals↗
PubMed1981

Waking and dreaming mentation: a test of their interrelationship.

The relationship of dream content to the immediate pre- and post-sleep mentation of the dreamer was studied using the electrophysiologically defined state of REM (rapid eye movement sleep) as dream collection time. The subjects were 20 male and 20 female volunteers, ages 18 to 25. Each slept for three non-consecutive nights in the laboratory and had REM awakenings and pre- and post-sleep verbal content collected. REM reports and waking verbal samples were scored on 18 Hall-Van de Castle content scales. The interscorer agreement of two judges was 0.90. Product moment correlations were performed on each of the 18 content categories between content of the REM reports and of the waking verbal samples. Across all 40 subjects, 9 out of 18 correlations were statistically significant and 14 of the 18 were positive. The zero-mu test indicated that the distribution of the 18 correlations was significantly different from zero. Thus it can be concluded that dream content is related to the psychological parameters of waking life, in a continuous rather than compensatory manner.

Adolescent↗
PubMed1981

Selective inhibition of T suppressor-cell function by a monosaccharide.

Interactions between regulatory T lymphocytes and other cells are assumed to occur at the level of the cell surface. T cells which suppress the generation of specifically effector cells have been described as having antigenic, idiotypic, allotypic and I-region specificity. Other T suppressor cells generated by in vitro cultivation with or without mitogenic stimulation have suppressive activity for T and B cells but no specificity can be assigned to them. These T suppressor cells (Ts) inhibit various lymphoid functions-this either reflects their polyclonal origin or indicates that the structures recognized by the Ts receptors must be common for many cell types. Carbohydrates on cell membrane-inserted glycoproteins or glycolipids might function as specific ligands for recognition by cellular receptors or soluble factors. Almost all cell-surface proteins of mammalian cells are glycosylated. There is evidence for lectin-like carbohydrate binding proteins not only in plants but also in toxins, viruses, prokaryotic cells and even mammalian cells, including T cells. A functional role for these lectin-like proteins has been described for slime moulds and suggested for the selective association of embryonic cells. We report here that addition of a monosaccharide can counteract the effect of T suppressor cells during the generation of alloreactive cytotoxic T cells (CTLs) in vitro.

Animals↗
PubMed1981

Periodic breathing in infants with histories of prolonged apnea.

Periodic breathing (PB) during sleep was investigated in two groups of full-term infants with histories of apnea that were terminated by resuscitation. One group of infants had been reported to be asleep whereas the other group had been reported to be awake when apnea was noted. Electrophysiologic sleep recordings were made after the apneic incident. The infants with histories of prolonged apnea while asleep exhibited more PB during recorded sleep than infants with histories of apnea while awake. Increased PB during sleep in full-term infants, therefore, may not be associated with all prolonged apneic episodes in infants but may be specifically associated with those episodes that occur during sleep.

Apnea↗
PubMed1981

Dose-related effects of flurazepam on human sleep-walking patterns.

Two consecutive nights of flurazepam at each of 15, 26, and 45 mg were compared to placebo in a Latin-square double-blind crossover design using 24 healthy young-adult males. Flurazepam had significant hypnotic effects on objective and subjective measures of efficacy: shorter sleep latency, longer sleep time, and fewer awakenings. It also induced morning sedation along with decrements in cognitive performance. Flurazepam had dose-related impacts on both human and computer-scored EEG-EOG parameters: less stages 3 + 4 and decreased EEG delta, less stage 1 REM and decreased REM density, more stage 2 and increased EEG spindling. Also, EEG alpha and movement artifact were decreased and EEG beta was increased. Only a few of the EEG-EOG variables and none of the subjective indices had cumulative changes on the two drug nights. Stage shifting was unaffected at the two lower doses on the first night but decreased at all three dose levels on the second night; percent stages 3 + 4 was unaffected on the first night but decreased at all dose levels on the second night. The rate of delta waveform activity was also diminished by a greater amount on the second night. This study conclusively established that flurazepam affects the EEG-EOG architecture of sleep on each of the first two nights of administration.

Adult↗
PubMed1981

A dose response study of the hypnotic effectiveness of alprazolam and diazepam in normal subjects.

One group of eight normal young males was administered three doses of alprazolam (0.25, 0.5 and 1.0 mg) and placebo, while a second group of eight normal young males was given three doses of diazepam (2, 5, and 10 mg) and placebo in the same design. All subjects slept in the sleep laboratory for 10 nights, 2 consecutive nights each week for 5 consecutive weeks. The first 2 nights served as adaptation. During the next 4 weeks subjects received a random dose of alprazolam (or placebo) or a random dose of diazepam (or placebo) each week. Similar dose-related benzodiazepine effects were found on sleep with both medications. Alprazolam reduced percent stage 4 and REM sleep and increased stage 2 sleep and latency to REM. Diazepam decreased percent stage 1 and increased percent stage 2 sleep. No drug by dose interactions were found. It was concluded that, while both drugs had similar effects on sleep, alprazolam showed significant effects on REM sleep parameters and might be evaluated for possible antidepressant effect.

Adolescent↗
PubMed1981

Gastroesophageal reflux in infants: relation to apnea.

The temporal relationship between apnea and gastroesophageal reflux was examined in 14 infants with abnormal GER scores and histories of prolonged apnea. Simultaneous polysomnographic and intraesophageal pH recordings were performed for each infant. GER episodes were compared to control segments of the recording (without GER) for frequency and type of apnea. Apnea was equally likely to occur during the control segments as during the GER episodes. Brief obstructive apneic episodes were more common during the onset of GER episodes than the onset of control segments. GER duration appeared prolonged during sleep. GER and apnea were not temporally related in the majority of instances, and may be two manifestations of a more general developmental delay.

Apnea↗
PubMed1981

Dose-related effects of phenobarbitone on human sleep-waking patterns.

1 Twenty-four healthy male subjects had two consecutive drug nights at 2-week intervals using placebo and 80, 140 and 240 mg doses of phenobarbitone in a double-blind cross-over design. 2 Phenobarbitone produced significant dose-related decreases in sleep latency and number of awakenings, along with increased total sleep time. 3 Both subjective and objective measures of sleep indicated the presence of cumulative (first v second night) effects of phenobarbitone, especially decreases in the number of awakenings and in delta waveform activity. 4 Measures of REM sleep were highly sensitive to phenobarbitone. The high dose decreased REM density to 30% of baseline on the first night and to 18% on the second night. 5 EEG alpha activity was decreased, beta activity was increased and sigma spindle activity was unaffected by phenobarbitone during sleep. 6 Subjects experienced some impairment of cognitive performance along with residual sedation the following morning.

Adult↗
PubMed1981

The interaction of age, performance and hypnotics in the sleep of insomniacs.

Scant attention has been paid to the objective evaluation of insomnia as a function of age, particularly with reference to increased drug sensitivity and resulting loss in balance performance. Therefore, the electroencephalographic sleep and the balance-board performance of 10 young and 12 geriatric insomniacs were studied under baseline and hypnotic drug (ketazolam) conditions. In terms of objectively measured sleep, the geriatric insomniacs had worse sleep on every dimension except sleep latency and percentage of stage-2 sleep. These differences between aged and young insomniacs, however, were no greater than might be expected as a function of normal aging. Drug-age interactions indicated that ketazolam differentially increased sleep efficiency, decreased the percentage of REM sleep, and eliminated any learning improvement on the balance board in geriatric versus young insomniacs. The findings indicate that the geriatric subjects were more sensitive to the hypnotic drug, in that their sleep improved to a greater extent. However, an important loss in balance performance was also observed.

Adult↗
PubMed1981

The acute effect of quazepam on the sleep of chronic insomniacs. A dose-response study.

The present study investigated the effects of the benzodiazepine, 7-chloro-5-(2-fluorophenyl)-1,3-dihydro-1-(2,2,2-trifluoroethyl)-2H-1,4-benzodiazeepine-2-thione (quazepam), on hypnotic efficacy and sleep staging in chronic insomniacs. We evaluated the acute withdrawal effects of several doses (0, 7.5, 30 and 45 mg) of quazepam. The effects of the different doses were assessed using both objective (polysomnographic) and subjective sleep parameters in a double blind repeated measures design (n = 15). The results indicated that daily administration of quazepam over three nights produced increased effects on sleep which suggested drug accumulation. Lower doses (7.5 and 15 mg) only had significant effects on sleep (sleep induction and maintenance and sleep architecture) with three days of administration, while 45 mg of quazepam produced significant effects on the first night of drug administration. Contrary to previous research investigating longer periods of administration, acute administration of low doses of quazepam did not produce carryover effects on withdrawal, while higher doses did. The accumulation of the parent compound or its active metabolites thus seemed to mediate these effects on sleep in a dose related fashion.

Adolescent↗
PubMed1981

[Haemodynamic effect of naloxone during electrostimulation analgesia with special reference to the role of endorphin (author's transl)].

10 persons undergoing cardiac surgery in electro-stimulation analgesia (ESA) with controlled ventilation were given 5 microgram/kg bodyweight and 10 microgram/kg body-weight respectively of naloxone during the operation and the effects of the drug on the circulation were registered over a period of 10 minutes. The observations do not support the view that endorphin plays a part in ESA. Other possible modes of action are discussed.

Dose-Response Relationship, Drug↗
PubMed1981

Guanosine polyphosphate production of Escherichia coli stringent and relaxed strains in the stationary phase of growth.

Stringent and relaxed Escherichia coli strains grown on minimal and on differently enriched media produced guanosine polyphosphates in the stationary phase of growth. On transition from the logarithmic to the stationary phase, stringent strains started to produce guanosine 5' triphosphate 3' diphosphate (pppGpp). and guanosine 5' diphosphate 3' diphosphate (ppGpp), while relaxes strains accumulated only ppGpp. When the stringent strain was cultivated on media enriched with Casamino Acids the leve of pppGpp decreased, while with yeast extract an almost twofold increase could be observed. The concentration of ppGpp increased with both nutrients as compared to that measured in minimal medium. Readdition of glucose to the stationary phase culture did not result in the slightest decrease of the nucleoside polyphosphate levels. In contrast, addition of a mixture of 20 L-amino acids or Casamino Acids or yeast extract to the medium caused an abrupt decrease in the guanosine polyphosphate levels. Qualitatively similar results were obtained with the relaxed strains except that the amounts of ppGpp were smaller than in the case of the stringent counterpart and the responses to the resupplementation were slower. Some possible mechanisms regarding the occurrence of guanosine polyphosphates in the stationary phase are discussed.

Culture Media↗
PubMed1981

[Cardiac and vascular effects of midazolam during induction of anesthesia prior to and during extracorporeal circulation in coronary-surgical patients (author's transl)].

8-Chloro-6-(2-fluorophenyl)-1-methyl-4H-imidazo[1,5-a] [1,4]benzodiazepine (midazolam, Ro 21-3981, Dormicum) is a new benzodiazepine which, when compared with its predecessors diazepam (Valium) and flunitrazepam (Rohypnol), has several outstanding advantages: We conducted hemodynamic investigations with 0.15 mg/kg b.w. midazolam in a total of 28 coronary patients divided into 3 groups. The new water-soluble benzodiazepine is at the dose given useful in the induction of and as an adjuvant to anesthesia because of its hemodynamic effect.

Anesthetics↗