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Biomedical subjects

J L Falk

Publications and source records attributed to J L Falk.

At least 109 records · Page 6Linked to original sources
PubMed1985

Selective acidosis in venous blood during human cardiopulmonary resuscitation: a preliminary report.

During experimental CPR, a marked venoarterial gradient in PCO2 has been reported. This is accompanied by a disproportionate decrease in venous pH and a simultaneous increase in arterial pH. This study includes a case report of human CPR in which simultaneous arterial and mixed venous blood gases were obtained before and after cardiac arrest. Similar venoarterial PCO2 gradients were observed subsequently in six additional patients during arrest. These clinical data indicate that arterial blood gases fail to reflect striking increases in venous PCO2 and decreases in pH due to respiratory acidosis on the venous side of the circulation.

Acidosis↗
PubMed1984

Midazolam-induced increase in NaCl solution ingestion: differential effect of the benzodiazepine antagonists Ro 15-1788 and CGS 8216.

After adaptation to a 23-hr water deprivation regimen, under which rats were allowed a daily 1-hr water rehydration session, they were injected (SC) with 1 or 2 drugs presession and given 1.5% NaCl solution to drink in place of water. Midazolam (0.5-1.0 mg/kg) increased the intake of 1.5% NaCl solution as did Ro 15-1788 (2.5-10.0 mg/kg). This confirmed a previously noted agonist effect of midazolam and partial agonist action of Ro 15-1788. When injected in combination with midazolam, Ro 15-1788 (2.5-10.0 mg/kg) antagonized the effect of midazolam. CGS 8216 (2.5-20.0 mg/kg) revealed no partial agonist action on the NaCl solution ingestion procedure nor did it block the effect of midazolam.

Animals↗
PubMed1984

Chlordiazepoxide injection elevates the NaCl solution acceptance-rejection function.

Injection (SC) of chlordiazepoxide (2-8 mg/kg) increased the intake of NaCl solution (0.5-3.0% NaCl) as well as water in water-deprived rats when these fluids were made available singly during daily 1-hr rehydration periods. The marked enhancement of this drug effect when NaCl solution was the available fluid does not appear to be due to the induction of a sodium appetite or the mimicking of an increase in water deprivation. The exaggeration of the drug effect when an NaCl solution is the drinking fluid, as opposed to water, may be useful as a sensitive index of action for punishment-attenuating (anxiolytic) drugs.

Analysis of Variance↗
PubMed1984

The relationship between oxygen delivery and consumption during fluid resuscitation of hypovolemic and septic shock.

The effects of increasing oxygen delivery (DO2) on oxygen consumption (VO2) in eight patients with septic shock and five patients with hypovolemic shock were studied during fluid resuscitation. In the septic shock group, DO2 increased from 315 +/- 29 to 424 +/- 25 ml/min/m2 (p less than 0.01) and VO2 increased from 134 +/- 8 to 151 +/- 7 ml/min/m2 (p less than 0.01). In the hypovolemic shock group, DO2 increased from 239 +/- 26 to 386 +/- 48 ml/min/m2 (p less than 0.01) and VO2 increased from 96 +/- 9 to 135 +/- 6 ml/min/m2 (p less than 0.01). There was no significant difference in either the increase in DO2 or VO2 between the septic shock and hypovolemic shock patients. We conclude that increasing DO2 by fluid resuscitation increases VO2 during both hypovolemic and septic shock.

Aged↗
PubMed1983

Drug dependence: myth or motive?

The acceptability of nonmedical use for a particular drug is a function of diverse social needs. Drug dependence is due less to intrinsic effects than to the situation in which drug taking occurs. An addictive level of drug self-administration is a symptom of behavioral troubles rather than a definition of the trouble itself. The intrinsic effects of drugs do not in themselves produce either misuse or evoke specific kinds of behavior such as sexual or aggressive activities. Drugs can, however, come to function as discriminative stimuli for socially sanctioned behavior that would not under other circumstances be tolerated. The intrinsic reinforcing potential of an agent evolves in and dominates situations in which other reinforcing opportunities are either absent or remain unavailable to an individual who is unprepared to exploit them. While certain intrinsic properties of a drug contribute to its potential as a reinforcer (e.g., rapid onset and brief duration of action), reinforcing efficacy is notoriously malleable. It is a function of historic and currently-acting factors, particularly social reinforcers. The importance of physical dependence in the maintenance of drug seeking and taking is mainly unproven and probably overrated. Situations under which important reinforcers are available only in small portions intermittently can induce various excessive activities, including an untoward concern with obtaining and using drugs. Drug dependence prevention as a species of environmental dependence can be best effected by either alterations in the intermittent reinforcement situations inducing excessive behavior or by providing opportunities and training with respect to reinforcing alternatives other than drugs.

Aggression↗
PubMed1983

Production of physical dependence on ethanol by a short drinking episode each day.

A 3-hr schedule-induced ethanol polydipsia regimen was used in rats to elevate blood alcohol concentration to a single intoxicating peak each day. After 3 weeks, and again after 3.5 months, animals were tested for the presence of physical dependence by exposure to a brief auditory stimulus (key shaking) at 7 and 11 hr after ethanol polydipsia. Withdrawal signs were observed only at 11 hr when blood ethanol levels had returned to zero. No such signs were observed when animals were made water polydipsic. While sufficient, continuous elevation of blood ethanol concentration is not necessary for the development of a demonstrable physical dependence. A limited daily ethanol binge was sufficient.

Alcohol Drinking↗
PubMed1983

Agonistic action of a benzodiazepine antagonist: effects of Ro 15-1788 and midazolam on hypertonic NaCl intake.

Rats adapted to a 23-hr water deprivation regimen were allowed a daily 1-hr water rehydration session. On test days the session drinking fluid was 1.5% NaCl solution rather than water. One group was injected (SC) with the benzodiazepine antagonist Ro 15-1788 (2.5-10 mg/kg) and another group with the agonist agent midazolam (0.13-2.0 mg/kg) every 5-6 days at 10 and 15 min before a test session, respectively. Both Ro 15-1788 and midazolam increased 1.5% NaCl solution intake in a dose-related manner. In this study and in previous research, benzodiazepines and barbiturates were shown to increase the intake of hypertonic NaCl solutions. The present results reveal a similar effect for Ro 15-1788, indicating an agonistic dimension to the spectrum of action of this specific receptor antagonist.

Animals↗
PubMed1983

Diazepam-induced NaCl solution intake: independence from renal factors.

Rehydrating rats injected with diazepam (8 mg/kg, SC) increased their intake of 2.0% NaCl solution. Neither bilateral nephrectomy nor bilateral ureter ligation interfered with the increased NaCl solution ingestion produced by diazepam. It is concluded that the increased intake of the NaCl solution is not secondary to renal water-electrolyte losses nor dependent upon intact renal benzodiazepine receptors.

Animals↗
PubMed1983

Fluid resuscitation in circulatory shock: a comparison of the cardiorespiratory effects of albumin, hetastarch, and saline solutions in patients with hypovolemic and septic shock.

Twenty-six consecutive patients in hypovolemic shock were randomized to fluid challenge with 5% albumin (A), 6% hetastarch (H), or 0.9% saline (S) solutions. Fluid challenge consisted of 250 ml of test fluid every 15 min until the pulmonary artery wedge pressure (WP) reached 15 mm Hg. Thereafter, WP was maintained at 15 mm Hg for an additional 24 h with infusions of the same test fluid. Vital signs, hemodynamic and respiratory variables, as well as arterial lactate and colloid osmotic pressure (COP) were monitored according to protocol. Chest x-rays were performed by standardized technique before fluid challenge and at 12 and 24 h of maintenance fluid therapy and were evaluated for evidence of pulmonary edema. Cardiac function and hemodynamic stability were restored by fluid challenge with A, H, and S. Two to 4 times the volume of S as A or H was required to achieve similar hemodynamic endpoints. COP was increased by fluid challenge with A or H but was markedly reduced by fluid challenge with S and throughout the 24-h maintenance period. Fluid challenge resulted in reductions in COP-WP gradient of 62% in the A, 43% in the H, and 125% in the S groups. Resuscitation with S resulted in a significantly higher incidence of pulmonary edema (87.5%) than did resuscitation with A (22%) or H (22%). Urine output was not different among the groups at any time during the study. We conclude that 6% H performs as well as 5% A as a resuscitative fluid and that resuscitation with either of these colloids is associated with a lower incidence of pulmonary edema than is resuscitation with 0.9% S.

Aged↗
PubMed1982

Complete reversal of chronic ethanol polydipsia by schedule withdrawal.

Rats exposed to daily 3-hr intermittent food delivery sessions (binging) chronically ingested excessive amounts of either H2O or 5% EtOH (mean 7.1 g/kg/3-hr). Withdrawing the intermittency of the feeding schedule once every 10 days (single-ration probe session) resulted in reduction of fluid intakes (both H2O and EtOH) to the level of animals always given daily single-ration sessions. This complete dependence of elevated fluid intake levels on the intermittent feeding schedule was unaffected by either the number of probes previously administered (0 to 11) or the duration the feeding schedule was maintained before introduction of the first probe session (29 or 109 days). The results of the probe sessions demonstrated that a history of ethanol overindulgence was not a sufficient condition for the maintenance of overdrinking. Continued overindulgence required the continued presence of the original inducing conditions. Ethanol-polydipsic animals exposed to periodic probe sessions also developed a slow rise in binge session intake. No such increase was observed in the water-polydipsic animals.

Animals↗
PubMed1981

Hemodynamic and metabolic effects of abdominal aortic crossclamping.

The hemodynamic and metabolic effects of aortic crossclamping and declamping were studied in 10 patients undergoing abdominal aortic reconstructive surgery. After placement of pulmonary and radial arterial catheters, measurements were obtained preoperatively, during the procedure according to protocol, and postoperatively. Pulmonary arterial wedge pressure was maintained at 10 to 15 mm Hg throughout the operation. Aortic cross clamping produced a significant increase in systemic arteriolar resistance and systolic blood pressure, with no change noted in the left ventricular stroke work index. Declamping decreased systemic resistance and produced no change in the left ventricular stroke work index. Clamping and declamping resulted in elevations of serum lactate. Central venous pressure correlated with pulmonary arterial wedge pressure in each patient and in the entire group. Cardiac function is not decreased by aortic crossclamping, and central venous pressure can usually be used for hemodynamic monitoring in these patients.

Adult↗
PubMed1981

Cross-tolerance to phenobarbital following chronic ethanol polydipsia.

Using contingent food pellet delivery, rats were trained on a discriminative motor control task requiring that a force transducer be held steadily within a force band. Motor performance following pre-task doses of phenobarbital (40, 60 or 80 mg/kg) both before and after 4 months fo chronic ethanol polydipsia (mean intake = 11.1 g/kg/kay)indicated the development of cross-tolerance from ethanol to phenobarbital. Days on which saline control injections were given in place of phenobarbital injections (on injection days ethanol was withdrawn 5 hr pre-injection) revealed the development of a mild physical dependence on ethanol at this level of ethanol polydipsia. Chronic ethanol polydipsia did not alter the time course of phenobarbital elimination from the serum, indicating that the cross-tolerance probably was due to central nervous system changes.

Alcoholism↗
PubMed1981

Barbiturate dependence and drug preference.

Rats exposed to a daily 3-hr session of intermittent food delivery ingested physical-dependent levels of a 1 mg/ml sodium phenobarbital solution. This chronic, voluntary, high level of session phenobarbital intake had no effect on 21-hr home cage barbiturate preference. Substitution of water for phenobarbital during the session after 7.5 weeks precipitated various spontaneous withdrawal signs in some of the animals by the 24th hr of drug withdrawal but no change was found in home-cage barbiturate preference at any time. Physical dependence alone does not seem to play a crucial role in the maintenance of drug intake behavior.

Animals↗
PubMed1980

Schedule induction and overindulgence.

An animal model of human alcoholism is presented in which animals maintain chronic overdrinking to the extent that they develop severe physical dependence. They can be induced to overdrink ethanol in situations where an alternative fluid is present as well, so that the overindulgence is elective. The environmental conditions that produce this result also can induce the overingestion of other substances, aggression, and hyperactivity. It would appear, then, that many kinds of seemingly excessive, maladaptive behavior in animals and humans can have similar environmental sources. Alcoholism may be viewed within a context of environmental conditions that can produce a variety of excesses.

Alcohol Drinking↗