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M Klein

Publications and source records attributed to M Klein.

At least 577 records · Page 32Linked to original sources
PubMed1986

Additional component in the cellular mechanism of presynaptic facilitation contributes to behavioral dishabituation in Aplysia.

Sensitization of defensive gill and siphon withdrawal reflexes in Aplysia results, in part, from presynaptic facilitation of transmitter release from mechanoreceptor sensory neurons that innervate the siphon skin and synapse with interneurons and motor neurons. Presynaptic facilitation also can be elicited by application of serotonin. This facilitation is associated with two phenomena, a prolongation of the presynaptic action potential resulting from a decrease in a specific K+ current and an enhancement of the Ca2+ transients elicited by depolarization. Previous work has shown that prolongation of the action potential enhances synaptic transmission at normal levels of release. Here we report that an additional set of processes also contributes to facilitation. When repeated activation of the sensory neurons induces profound homosynaptic depression, prolonging the duration of action potentials (or of depolarizing commands under voltage clamp) has little effect on transmitter release. Nonetheless, serotonin is still capable of enhancing release. Since homosynaptic depression underlies the behavioral process of habituation, the second set of processes, by counteracting the consequences of the depression, seems to mediate the effects of dishabituation in the sensory neuron. Prolongation of the action potential by closure of the K+ channel seems to mediate the effects of sensitization.

Action Potentials↗
PubMed1986

[Nutrient dependence of energy preservation requirements in rats. 1. Dependence of energy requirements for preservation in fully-grown rats on the type of nutrient offered as the sole energy source].

In two experiments with fully-grown albino rats (Wistar strain) the energetic utilization of glucose, sunflower oil and casein in the maintenance metabolism was determined under thermoneutral conditions of keeping the animals. The relative requirement of metabolizable energy for maintenance was, with either glucose, sunflower oil or casein being the sole energy source of the feed, in experiment 1 100:105:133 and in experiment 2 100:102:135. The absolute values of the maintenance requirement of metabolizable energy were in experiment 1 347 +/- 26, 364 +/- 61 and 460 +/- 33 resp., and in experiment 2 330 +/- 11, 337 +/- 21 and 446 +/- 27 kJ/kg LW 0.75 resp. The results are discussed in connection with the efficiency of ATP synthesis (metabolizable energy/mol ATP gain) in the oxidative decomposition of nutrients.

Adenosine Triphosphate↗
PubMed1986

[Nutrient dependence of energy preservation requirements in rats. 2. Effect of the protein level of feed and the environmental temperature on the energy preservation requirement and heat production in fully-grown rats].

The influence of protein in exchange for carbohydrates on the energy maintenance requirement was studied with nearly fully-grown rats at ambient temperatures between 33 and 21 degrees C. The levels of the crude protein content were 10, 25, 40 and 70%. At an ambient temperature of 33 and 30 degrees C energy maintenance requirement increased with the growing protein content in the feed. At a temperature of 30 degrees C the following values of energy maintenance requirement were measured in the sequence of the protein levels mentioned: 330 +/- 11, 347 +/- 18, 360 +/- 15 and 399 +/- 15 kJ metabolizable energy/kg live weight 0.75 X d. The occurring changes largely coincide with the expected values calculated from the efficiency of the ATP synthesis in the oxidative catabolization of protein and carbohydrates. At ambient temperatures of less than 30 degrees C, thermogenous effects after the exchange of protein versus carbohydrates could only be observed partly or not. 30 degrees C in feeding on the maintenance level and 33 degrees C in the state of hunger are estimated as the lower critical temperatures. Below the critical temperatures down to 24 degrees C heat production increased less per 1 degree C temperature decrease both in hungry and fed rats than in the temperature range between 24 and 21 degrees C. By the decrease of the ambient temperature from 24 to 21 degrees C the heat production of the hungry or fed rats increased by 39 or 33 kJ/degrees C X kg live weight 0.75 X d.

Animals↗
PubMed1986

[Dependence of energy maintenance requirements on nutrients in rats. 3. Effect of the protein levels of food on the energy maintenance requirements of growing rats].

In addition to earlier experiments with growing rats on the protein levels 10, 25 and 40% crude protein in the dry matter of the feed (Hoffmann et al., 1982 a), two groups of nine male Wistar rats each received feed mixtures with 6 or 25% crude protein resp. and energy metabolism on the energy maintenance level in an N equilibrium or with a positive N balance resp. were measured on 6 levels of live weight between 65 and 250 g and additionally also at subsequent fasting day. Energy maintenance requirement on average of the 6 periods amounted to 381 and 377 kJ metabolizable energy/kg W 0.75 X d on a low or middle protein level resp. and thus did not show changes at the decrease of N retention to values of about zero even with regard to different ATP formation capacities of the nutrients.

Animal Feed↗
PubMed1986

Human T-cell receptor genes: organization, diversity, and polymorphism.

The analysis of 27 human beta cDNA clones has revealed striking insights as to the germ line, combinatorial, and somatic mechanisms that operate to diversify V beta gene segments. It appears that the repertoire of human V beta genes is limited to 60 or so functional gene segments. Deletional mapping together with the analysis of large DNA fragments by field inversion gel electrophoresis and the isolation of cosmid clones should permit us to map the entire human V beta gene family. The polymorphisms that are present in these V beta gene segments will facilitate a search for interesting disease associations. A detailed comparison of the mouse and human V beta loci should permit us to come to understand in more detail the evolutionary mechanisms that have created these fascinating gene families.

Base Sequence↗
PubMed1986

Monocyte-associated acid phosphatase isoenzyme profiles as determined in acute myeloid leukaemia cells.

The acid phosphatase (acP) isoenzymes from the blast cells of 102 cases of acute myeloid leukaemia were separated by isoelectric focusing on horizontal polyacrylamide gels. The cases were classified on the basis of the FAB cooperative group criteria. Several single bands were combined into groups (I-IV). An increase in the number of acP isoenzymes was noted which paralleled the assumed maturation along the granulocytic cell lineage from FAB M1 to FAB M3 and along the monocytic cell lineage from FAB M4 to FAB M5. One isoenzyme which was resistant to tartrate inhibition was found in 40% of the monocytic variants FAB M4 and M5, but not in the nonmonocytic cases FAB M1-M3 and M6. This particular isoenzyme, which has been described as being characteristic for hairy cell leukaemia, also appears to be a marker of the monocyte/macrophage system and the respective neoplastic counterparts. The FAB M4 and M5 patients expressed a characteristic profile of group I isoenzymes which allows for the discrimination between monocytic and nonmonocytic cells.

Acid Phosphatase↗
PubMed1986

The inhibition of flexor tendon adhesions.

In a single blind control study using adult rabbits, the effectiveness of locally applied dextran-70 and 1% hyaluronic acid were evaluated in the control of flexor tendon adhesions after laceration of the profundus tendon in Zone II. Dextran-70 proved effective, whereas application of hyaluronic acid did not.

Animals↗
PubMed1986

[Drug intolerance reactions in the perioperative phase--pathophysiology, diagnosis, therapy].

The increase in allergic reactions compels the anaesthetist to exercise great care when administering anaesthetics exclusively intravenously, because anaphylactic or anaphylactoid reactions can become a life-threatening problem for the patient within a very short time. Unfortunately the information given by patients is often very incomplete and the risk of allergic reactions is not eliminated by false positive or negative results in the skin test. There are only a few drugs available as antigens for the RAST test. Apart from avoiding histamine-releasing drugs, this information gap can only be countered in high-risk patients by preoperative prophylaxis with H1 and H2 receptor antagonists.

Anaphylaxis↗
PubMed1986

Lymphocytotoxins in vasculitis. Correlation with clinical manifestations and laboratory variables.

Twenty-eight of 53 patients with various types of vasculitis were found to have cold reacting lymphocytotoxins (LCT). LCT were cytotoxic to both peripheral blood B and T cells as well as to OKT4 and OKT8 subpopulations. The interaction with the B cells was more pronounced than with the T cells as shown by reactivity with the former at higher serum dilutions than with the latter. Similar results were obtained with eluates from the unseparated lymphocytes and from B or from T cells. Partial purification of LCT demonstrated that they belong to the IgM class. LCT correlated with the level of circulating immune complexes as determined by the fluid phase C1q binding assay, but they did not correlate with the level of immunoglobulins, complement or antinuclear factors. The presence of LCT correlated significantly with the activity but not with the disease duration or the number of involved organs. Correlation of LCT with the activity of vasculitis implies that these cytotoxins may have a pathogenetic role and perhaps may serve as a marker for disease activity.

Antigen-Antibody Complex↗
PubMed1986

Correlation of surface marker expression with morphologically and immunologically defined subclasses of acute myeloid leukaemias.

The expression of myeloid-associated cell surface antigens detected by monoclonal antibodies (MoAb: MCS-2, MCS-1, MY7, MY9, Leu-M1, OKM1, VIM-D5, Mol, My-1, MY8, MY4, Leu-M3, VIM-D2, Mo2) of the HLA-DR/Ia-like antigen and of the Fc-receptor was determined on the blast cells from 91 patients with acute myeloid leukaemias classified as M1-M5 in the French-American-British (FAB) system. The surface antigen analysis revealed a highly heterogeneous reaction profile. Nevertheless, distinctive patterns of marker expression referring to morphologically defined subgroups were delineated. Several MoAb (especially MCS-2 and MY7 which were positive in most cases of the five FAB subgroups) appear to be useful for the recognition of myelomonocytic cells regardless of the commitment to either the granulocytic or monocytic cell lineage whereas other Mo Ab (especially MY4, Leu-M3, VIM-D2, Mo2) react predominantly with the monocytic variants and are helpful in the identification of monocytic commitment. The 91 cases could be divided into three immunologically defined phenotypes (Types I-III) corresponding to sequential differentiation levels. Correlations of these MoAb-defined phenotypes with the FAB subtyping showed that immunological and morphological classifications are not completely concordant and that only the parameters Type I and FAB M1 were significantly related. A scheme of early myeloid differentiation sequences based on the expression of surface antigens is presented.

Adult↗
PubMed1985

Iron poisoning--a preventable hazard of childhood.

We retrospectively studied the records of all patients with poisoning due to excessive iron ingestion admitted to a children's hospital during a 7 1/2-year period. There were 80 such children, aged between 0,6 and 3,93 years. Almost half were severely poisoned. Most children took iron tablets intended for their mothers or aunts as a supplement during pregnancy. These were packed in easy-to-open plastic packets. Estimates of the number of tablets taken were unreliable. All 29 children who received parenteral desferrioxamine (Desferal; Ciba) on presentation survived, whereas 3 of the 51 children in whom desferrioxamine therapy was delayed died. Late morbidity from brain damage and intestinal strictures was not assessed. Many cases of iron poisoning in childhood could be prevented by strip-packaging of iron tablets. Parenteral desferrioxamine should be given without delay whenever a child is suspected of having swallowed excessive iron tablets.

Child, Preschool↗