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At least 19 recordsLinked to original sources

PubMed1979

Shock as a signal for shock or no-shock: a feature-negative effect in conditioned suppression.

Rats were trained in conditioned suppression discriminations where shock at the beginning of a trial signaled either shock or no-shock at the end of the trial. In the shock-positive condition, shock at the beginning of a presentation of white noise signaled that noise would end with shock; noise that did not begin with shock did not end with shock. In the shock-negative discrimination, shock at the beginning of noise signaled that noise would not end with shock; presentations of noise that did not begin with shock ended with shock. In shock-random training, shock at the beginning of noise did not reliably signal whether the noise presentation would or would not end with shock. Most subjects in shock-negative training quickly developed a differential pattern of suppression on positive (shock reinforced) trials and no suppression on negative (nonreinforced) trials. The shock-positive discrimination was much more difficult to establish and was not acquired by the majority of the rats. This "feature-negative" effect is a clear exception to the general superiority of feature-positive learning commonly observed in discriminations based on a single distinguishing feature. The results are discussed in terms of Pavlovian stimulus-shock contingencies in the shock-positive and shock-negative paradigms, which appear to favor rapid development of the shock-negative discrimination.

Acoustic Stimulation↗

PubMed1976

Effects of electric-shock delivery on schedule-induced water intake: delay of shock, shock intensity, and body-weight loss.

In each of four experiments, schedule-induced water intake in the rat was studied under fixed-time 40-sec food delivery. Experiments I and II studied the temporal relationship between response-independent electric-shock delivery and licking. Shock was delivered under a variable-time 60-sec schedule. A lick-dependent delay was imposed so that licking and shock delivery were systematically separated in time by a minimum of 1 to 15 sec. Over a wide range of shock intensities the data failed to reveal a consistent delay-of-shock effect. Similar shock intensities led to similar reduction of water intake at each delay of shock interval. Experiments III and IV studied the effects of body-weight loss on water intake during independent shock delivery. In Experiment III, shock was delivered under variable-time 60-sec with a minimum separation between shock and licking of 5 sec. In Experiment IV, shock was delivered under variable-time 180-sec. The minimum separation between shock and licking was 10 sec. In each study, the resistance of water intake to suppression by shock delivery increased as the degree of body-weight loss increased. Schedule-induced water intake was affected more by shock when the animal was maintained at 90% of free-feeding weight than at 70%.

Animals↗

PubMed1975

Sepsis, resuscitated hemorrhagic shock and "shock lung:" An experimental correlation.

Dogs were submitted to hermorrhagic shock, resuscitated shock and resuscitated shock plus a pulmonary bacterial insult. Pulmonary familure was absent in dogs submitted only to shock or to shock and its resuscitation. The addition of usually sub-lethal amounts of micro-organisms to the shock-resuscitated lung caused rapid death from pulmonary failure. Pulmonary failure was demonstrated by increased lung weight, hypoxemia, decreased compliance and a hemorrhagic destruction of lung tissue. These findings strongly support recent concepts of an infective genesis of "shock lung" in man.

Animals↗

PubMed1976

[Effects of signal-shock contingency probability on gastric lesions in rats as a function of shock region (author's transl].

Effects of signal-shock contingency probability on stress pathology were studied with 2 regions of electric shock and with (a) only sound signal presentations (NS), (b) unrelated presentations of the signal and tail shock (TS) or foot shock (FS) (NPS), (c) signal presentations all of which were paired with the TS or FS (100 PS), or (d) signal presentations, 50% of which were paired with a TS or FS (50 PS). Rats in NPS and 50 PS groups with TS showed more stress-induced pathology than animals in the 100 PS groups with TS. However, the 100 PS group with FS resulted in greater gastric lesions than NPS, 50 PS, or NS group. The interaction between shock region and signal-shock contingency probability plays an important role.

Animals↗

PubMed1979

Influence of PCPA, shock level, and home-cage conditions on shock-induced aggression.

In a series of experiments, the effect of parachlorophenylalanine (PCPA) on shock-induced fighting was assessed rats raised and maintained under either a 12-hr alternating light-dark cycle (LD) or constant light conditions (LL). PCPA increased shock-induced aggression only in LL groups when testing was accomplished using a 2 mA shock; PCPA resulted in increased aggression in groups from the LD condition only when testing was done at 1 mA. A procedure that used castrated and intact cagemates to manipulate home-cage social experience provided evidence for a role for social experience in determining differences between LL and LD reared rats in shock-induced aggression. However, these data also suggested that home-cage social experience was not a factor in the lighting condition influence on the effect of PCPA on shock-induced aggression. Finally, a separate experiment demonstrated that diurnal rhythms in shock-induced aggression were disrupted by handling and vehicle injection in the control procedures, so the possible role of serotonin in diurnal rhythms of aggression behavior could not be assessed.

Aggression↗

PubMed1979

[Therapy of so-called shock lung. Experimental animal studies of the lung in shock].

1. Under hemorrhagic-traumatic shock conditions the depression of the flow and the pressure in pulmonary arteria and of the pressure in the left atrium was significant. The elevation of the pulmonary vessel resistance was significant, the pulmonary circulation time was longer. The depression of the oxygen partial pressure in arterial and venous blood was significant. 2. In comparison to single re-transfusion of the taken blood, the re-transfusion and application of 6-Methylprednisolone (Urbason; 30 mg/kg) could raise the pulmonary pressure and the flow in the pulmonary arteria and the oxygen pressure in the arterial and venous blood over their basic level. 3. After re-transfusion and simultaneous addition of phenoxybenzamine a renewing shock took place caused by a relative hypovolemia. 4. The hemodynamic circulation in the pulmonary and peripherial vessels was restored by hemodilution. While a single infusion of Haemaccel intensified the hypoxemia in comparison to shock conditions, the infusion of albumin (4%) caused no change in measured values. The application of Urbason (30 mg/kg) combined with Haemaccel-infusions raised the arterial and venous oxygen pressure significantly, in comparison to the hypotonic-phase they exceeded the basic values.

Animals↗

PubMedDate not supplied

[Involvement of the thyroid gland in clinical shock (anti-shock action of propylthiouracil)].

Propylthyouracil, a synthetic anti-thyroid drug, was given intravenously in ten patients in a severe shock condition and its action was followed on the blood cathecholamines. This was assessed in venous blood according to a modified colorimetric method by Manuhin, before and 30 minutes after the substance was perfused. Although statistically non-significantly the two amines show a tendency to fall after the administration of the drug. In line with a series of previous studies carried out in various institutes of chemical and pharmaceutical research the drug was given for the first time in humans in shock conditions. Discussing the results obtained the administration of propylthyouracil is recommended, as an adjuvant therapy in severe shock.

Adrenal Glands↗

PubMed1978

Glucagon treatment of hemorrhagic shock: improved survival and metabolic parameters in a murine shock model.

One hundred-twenty Sprague-Dawley rats were shocked at 60 torr for 60 minutes and at the end of this period shed blood was reinfused. The animals were divided into three groups at random. These groups were either treated by N saline or glucose in N saline or glucagon in N saline. Glucagon treatment resulted in increased liver and muscle glucose-glycogen stores in the late period following shock. This was associated with a decrease in liver pyruvate and lactate and improved survival. It appears that glucagon more favorably affects the response to shock in this model than does treatment with glucose or saline.

Animals↗

PubMed1978

The products of the "heat-shock" loci of Drosophila hydei. Correlation between locus 2-36A and the 70,000 MW "heat-shock" peptide.

Antibody was raised against total Drosophila hydei embryonic cellular protein with a molecular weight between 65,000 and 70,000 dalton. This antiserum reacted with the 70,000 MW "heat-shock" peptide found in "S labelled cell extracts of "heat-shocked" D. hydei tissue culture cells or salivary glands.--The antibody was coupled to Sepharose 4B and this material was used to absorb polysomes obtained from tissue culture cells incubated at 37 degrees C in the presence of tritiated RNA precursors. The relative concentrations of various RNA species complementary to the "heat-shock" loci 2-32A, 2-36A, and 2-48C in either bound, non-bound, or total polysomal material was then determined by in situ hybridization. The RNA species complementary to locus 2-36A was found to be enriched in the bound polysomal material.

Animals↗

PubMedDate not supplied

The effect of shock separation time on multiple-shock defibrillation.

Reports in the literature of studies of the efficacy of multiple, staggered shocks used for cardiac defibrillation have shown widely varying results. Twin half sinusoids, separated by an integral number of 60-Hz half-cycles, were used for transthoracic defibrillation of dogs. The separation of the pulses was varied from 0 to 13 half-cycles (0 to 108 msec). An online computer was used to determine the energy content of each shock and to obtain curves of the percentage of success vs energy, current, and voltage. The results show that 2 pulses, separated by 9 half-cycles (75 msec), require 57 percent of the peak current and 87 percent of the peak voltage required by a single pulse. The energy requirement, however, was 9.9 percent higher with the staggered shock. Other pulse separations required higher voltages and currents. Possible mechanisms for the effect are discussed.

Animals↗

PubMed1978

The shock liver. Clinical and biochemical findings in patients with centrilobular liver necrosis following cardiogenic shock.

Five patients with severe heart disease developed cardiogenic shock of more than 24 hours' duration. As a sequela to the shock, severe liver affection was demonstrated. Serum aspartate aminotransferases and serum lactate dehydrogenases showed very high activities. The prothrombin-proconvertin index was reduced to less than 25% of the normal. Four of the patients were jaundiced. The condition gave rise to some differential diagnostic problems. Liver biopsies were available from four of the patients, and histological examination of an autopsy specimen of the liver was performed in each case. The liver histology showed centrilobular necrosis and haemorrhage in all patients. It seems that centrilobular fibrosis develops later in the condition. The pathogenesis of this liver affection is probably hypoxic injury to the centrilobular areas of the liver lobule due to reduced liver blood flow.

Aged↗

PubMed1977

[Septic shock in the uroseptic patient. I. General and specific pathomechanisms of the septic shock (author's transl)].

Failure of microcirculation in septic shock is due to the generalized release of catecholamins following a fall in cardiac output by the activity of bacterial toxin. The failure of the microcirculation can be defined as 1. a failure of the distribution of the tissue perfusion, and 2. a decrease of capillary flow due to obstructed inflow, reduced capillary flow passage and obstructed outflow. Bloodviscosity increases because of fluid sequestration, aggregation of rbc's and decrease in velocity of the blood flow. All this results in a dispariaty of oxygen consumption and availability to the tissue. The characteristics of specific organ disturbances in shock go along with the distribution of the alpha-receptors in each organ, the specific physiological function and architecture of the organ as well as previous diseases of the organ.

Angiotensin II↗

PubMed1978

Is shock-induced lung fibrosis reversible? A report on recovery from "shock-lung".

As the consequence of a road accident a 19-year-old man developed respiratory insufficiency. Radiology and gas analysis revealed signs of "shock-lung". Morphometric analysis of a punch biopsy from the lung confirmed the diagnosis. Gas exchange grew worse in spite of conventional treatment. At the end of the third week after the trauma the maintenance of a highly negative fluid balance and the administration of high doses of corticoids were given a trial. The patient recovered. Although no functional pulmonary deficiencies remained, years later the patient still shows radiological evidence of extensive scarring. The lung parenchyma is intact, as judged by morphometric examination. This case shows that patients with "shock lung" can recover, but scars in the extrapulmonary space can remain, even though the lung parenchyma returns to normal.

Accidents, Traffic↗

PubMed1979

Anaphylatoxin-induced shock and two patterns of anaphylactic shock: hemodynamics and mediators.

In the dog, different cardiorespiratory reactions were identified in two types of anaphylactic shock and in C5a-AT (anaphylatoxin)-induced shock. All three types had in common a portal blood pooling with consequent decrease in the venous return, cardiac output, and arterial pressure. In anaphylaxis (a) of the first type, at a low titer of hemagglutinating antibodies, the latent period was 68 s and heart and lung function was unchanged. In the second type, at high titer, the latency was 19 s and pulmonary hypertension and decreased heart contractility occurred. After AT injection pulmonary hypertension appeared with tachypnea and unchanged heart function. Tachyphylaxis, but not cross-over tachyphylaxis against the anaphylactic agent and AT was observed in dogs and isolated guinea pig lungs. AT induced a transient release and a, a prolonged release of histamine, prostaglandins (PGs), and thromboxane A2 and endoperoxides from guinea pig lungs. SRS-A was released only in a. Indomethacin inhibited AT-induced release of PGs in guinea-pig lungs and AT-induced hypotension in the dog though it did not prevent the drop in cardiac output. These model studies suggest that different patterns of clinical a. can occur, depending on the type of antibodies and/or mediators involved.

Anaphylatoxins↗

PubMedDate not supplied