[The radicular post. Specifications]

The radicular pivot, the key component in Richmond and Davis crowns, was initially devised to maintain a permanent link between an artificial crown and the residual root of a monoradicular tooth. The success of such structures depends on three parameters: pivot rigidity (to prevent its fracture or deformation), rigidity of the link of between pivot and artificial crown, permanence of the cemented junction between pivot and root (pivot retentivity).

[The value of velocimetric investigation of the uterine arteries in retro-placental hematoma. 3 cases]

Retro-placental hematoma is a sudden event with a serious prognosis which is aggravated by the very frequent absence of premonitory clinical, biological or ultrasonic signs. Does a velocimetric investigation of the uterine arteries have any predictive value in this disorder? The apparatus used was a continuous Doppler with spectral analysis and a 4 MHz probe no ultrasonic location. Each examination involved the exploration of 2 uterine arteries and of the umbilical flow. The method of recording the uterine arteries is described. Three cases of retro-placental hematoma are reported. In these three cases, an increase in the resistance index of one of the uterine arteries (the right artery in 2 cases and the left in 1 case) was detected with the presence of a protodiastolic notch on the trace, whereas the umbilical index itself was normal and no other sign was present which could predict the placental event. The value of the Doppler recording is already established in many obstetric indications, and these should be extended yet further, particularly if this preliminary study is confirmed on a larger scale.

[Prognosis of canal treatment. Success and failure]

This clinical review confirms the very positive prognosis for endodontic therapy, conditional to strict compliance with imperatives. Endodontics failures are transient and can be remedied. The authors define the attitude to be adopted and the measures to be taken in accordance with the type of difficulty encountered.

Effect of chronic caffeine administration on theophylline concentrations required to produce seizures in rats

Caffeine as well as the antiasthmatic drug theophylline can cause seizures when administered to humans or animals in excessive doses. Studies on rats have shown rapid development of functional tolerance to caffeine-induced seizures whereas repeated pretreatment with theophylline had no significant effect on the theophylline concentrations required to produce seizures. The purpose of this investigation was to determine whether chronic exposure to caffeine can affect susceptibility to the convulsant effect of theophylline. Rats received caffeine, 40 mg/kg, or solvent twice a day for 7 days as an intravenous injection. On the eighth day, theophylline was infused intravenously until the onset of maximal seizures. At this pharmacologic end point, rats pretreated with caffeine had significantly higher theophylline concentrations in the brain and cerebrospinal fluid than did control (solvent-pretreated) animals. Although the concentration differences were relatively small (approximately 11%), they demonstrate in principle the development of caffeine-induced tolerance to the neurotoxic effect of theophylline. Additional experiments showed that the caffeine effect on theophylline neurotoxicity is not acutely mediated by paraxanthine, a major metabolite of caffeine.

Kinetics of drug action in disease states. XXXIX. Effect of orally administered activated charcoal on the hypnotic activity of phenobarbital and the neurotoxicity of theophylline administered intravenously to rats with renal failure

The central nervous system (CNS) sensitivity to the hypnotic (general anesthetic) action of phenobarbital and to the neurotoxic (convulsive) action of theophylline is greater in rats with acute renal failure than in normal animals, consistent with clinical observations. In the case of phenobarbital, this increased sensitivity can be produced in normal rats by infusion of a solution of the lyophilized dialysate of serum from rats with renal failure. It was hypothesized that the relevant constituent(s) of this dialysate may circulate between the blood and the intestinal lumen and that it (they) can be adsorbed by orally administered activated charcoal and thereby removed from the body. If so, treatment of renal failure rats with activated charcoal should partly reverse the increased CNS sensitivity to phenobarbital and to other drugs similarly affected. Accordingly, rats with renal failure produced by bilateral ligation of ureters were given an aqueous suspension of activated charcoal, about 1 g per kg body weight, orally every 8 hr for six doses. Uremic controls received equal volumes of water. About 2 hr after the last dose, the animals were infused i.v. with phenobarbital to onset of loss of righting reflex or with theophylline to onset of maximal seizures. In the phenobarbital study, charcoal treatment partly reversed the hypothermia associated with renal failure and caused a reduction of creatinine and total bilirubin concentrations in serum. The cerebrospinal fluid (CSF) concentration of phenobarbital at onset of loss of the righting reflex was significantly higher in charcoal treated rats than in their controls.(ABSTRACT TRUNCATED AT 250 WORDS)

Procoagulant activity in gastroenterology

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Histopathology of cocaine hepatotoxicity. Report of four patients

Although cocaine is believed to be hepatotoxic for humans, the hepatic histopathology has been reported in only 1 patient. That patient had zone-1 necrosis. We have encountered 4 patients with liver injury secondary to cocaine use, 1 of whom died. The biopsies from two patients showed well-demarcated zone-3 necrosis identical to that seen with acetaminophen toxicity. The patient who died had necrosis of almost all hepatocytes as found at biopsy and autopsy. Biopsy was performed on another patient after resolution of the illness, and showed hyperplastic endoplastic reticulum but no necrosis. All patients had mild large- and small-droplet steatosis in surviving hepatocytes. Inflammation was mild. Drug screenings performed on all patients showed the presence of a cocaine metabolite and the absence of acetaminophen, alcohol, and other potential toxins. Patients typically had early marked increase and rapid decrease of serum aminotransferases, mild-to-moderate increase in prothrombin time, myoglobinuria, and moderate azotemia. The predominant pattern of zone-3 necrosis is similar to that reported of mice given cocaine.

Fulminant hepatitis

In conclusion, evidence exists that cellular and humoral immune-mediated processes result in hepatic necrosis in FH. Activation of the immune coagulation system appears to be an integral part of the inflammatory process resulting in fibrin thrombi which have been demonstrated in the liver, kidneys and lungs of patients with FH. A beneficial role of PG in the treatment of FH has been demonstrated, but controlled trials are required to firmly establish the efficacy of these agents. At present liver transplantation remains the treatment of choice in selected patients with FH. Further studies of the role of the immune system in the pathogenesis of this disease are required to devise more effective therapeutic strategies.

Kinetics of drug action in disease states. XXXVI: Effect of cyclosporine on the pharmacodynamics and pharmacokinetics of a barbiturate (heptabarbital) in rats

Pretreatment with cyclosporine reportedly prolongs the effect of certain general anesthetics in humans and the sleeping time of mice after pentobarbital administration. This investigation was designed to determine the mechanism(s) of the cyclosporine-barbiturate interaction. Adult female Wistar rats received cyclosporine (50 mg/kg im) or saline solution daily for 3 days. On the third day, they were injected with heptabarbital (45 mg/kg iv). Other cyclosporine-treated and control groups were infused with heptabarbital until they lost their righting reflex. Treatment for 3 d with cyclosporine was associated with decreased rectal temperature, decreased magnesium concentrations in serum and CSF, increased serum creatinine and urea nitrogen concentrations, elevated serum aspartate aminotransferase activity and total bilirubin concentration, decreased serum total protein concentration, and increased hematocrit. These physiologic changes are consistent with the clinically observed hypomagnesemia, nephrotoxicity, and hepatotoxicity in patients treated with cyclosporine. Control rats slept for 90 +/- 14 min (mean +/- SD, n = 9) after heptabarbital injection, whereas cyclosporine-pretreated rats slept for 154 +/- 22 min. Compared with controls, cyclosporine-pretreated rats awoke (after heptabarbital injection) and went to sleep (after heptabarbital infusion) with significantly lower barbiturate concentrations in serum and CSF. Pretreatment with a single 60-mg/kg im dose of cyclosporine 2 h before heptabarbital infusion caused no significant biochemical changes approximately 160 min later, except for elevated serum aspartate aminotransferase (which occurred also after injection of the surfactant-containing vehicle) and serum bilirubin. Again, heptabarbital concentrations at onset of sleep (loss of righting reflex) in serum, brain, and CSF of cyclosporine-treated rats were significantly lower than in saline-treated controls.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of multiple dosing on the analgesic action of diflunisal in rats

This investigation was designed to compare the analgesic effect of the initial dose of a repetitively dosed non-narcotic analgesic with the analgesic effect of a subsequent dose given 3 days later. To exclude gradual drug accumulation as a variable, the first ("loading") dose was larger than the maintenance doses. Male Sprague-Dawley rats received 100 mg/kg diflunisal i.v. as the first dose and 70 or 75 mg/kg every 12 hours thereafter. The analgesic effect of the first and seventh doses was determined as the pain threshold (voltage) upon electrical stimulation of the tail every 15 to 30 minutes from the third to the ninth hour after dosing. Blood samples for drug assay were obtained at 3 and 9 hours. A control group received injections of solvent for 6 doses and 100 mg/kg diflunisal as the seventh dose. There were no statistically significant differences between the area under the total or free (unbound) drug concentration versus time curves of the first and seventh dose but the average analgesic effect (area under the voltage increase versus time) of the seventh dose was only 28 percent that of the first dose. The areas under the drug concentration and analgesic effect versus time curves of the diflunisal dose given as the seventh injection to the control rats were similar to those produced by the first dose given to the multiple dosed rats. The results of this investigation show that the analgesic effect of a non-narcotic drug decreases substantially during repeated dosing in an animal model of experimental pain. This change in pharmacologic response has the characteristics of functional rather than pharmacokinetic tolerance in that there was no change in the drug concentration profile with time and no effect of the manipulations as such (i.e., repeated pain threshold determinations and blood withdrawals) on diflunisal-induced analgesia. These observations may have important implications for the evaluation and use of non-narcotic analgesics in the management of clinical pain.

Kinetics of drug action in disease states. XXXVII. Effects of acute fluid overload and water deprivation on the hypnotic activity of phenobarbital and the neurotoxicity of theophylline in rats

Fluid overload and dehydration are potentially serious physiologic perturbations. Their effects on the pharmacodynamics of drugs are essentially unknown. This investigation was designed to determine the effects of acute fluid overload or water deprivation on the hypnotic activity of phenobarbital and on the neurotoxicity of theophylline in male Lewis rats. In the first experiment, 5% dextrose in water (D5W) was infused i.v. in an amount equal to 5 or 10% of body weight and phenobarbital was infused immediately thereafter until the onset of loss of righting reflex (LRR). The total infused dose and the serum and cerebrospinal fluid (CSF) concentrations of phenobarbital at that time were significantly lower than in control animals. When phenobarbital was infused about 2.5 hr after D5W, the infused dose and the serum and CSF concentrations of phenobarbital at LRR were normal. When the rats received D5W and an injection of vasopressin, 25 I.U./kg, or vasopressin only, the infused dose and the serum and CSF concentrations of phenobarbital at LRR were significantly lower than in controls despite the 2.5-hr interval between the respective pretreatments and the phenobarbital infusion. Water deprivation for 24 or 48 hr had no significant effect on phenobarbital dose and concentrations at LRR. Intravenous infusion of D5W to 10% of body weight immediately or 2.5 hr before theophylline infusion had no significant effect on the total infused dose and the serum and CSF concentrations of theophylline at onset of maximal seizures. This lack of effect occurred despite appreciable hyponatremia and hypomagnesemia immediately after D5W infusion.(ABSTRACT TRUNCATED AT 250 WORDS)

[Tubal adenocarcinoma. Apropos of 4 cases and review of the literature]

The authors describe 4 cases of tubal cancer reported in the gynaecology department of the University Hospital in Caen and review the international literature. If all authors are in agreement on the early symptoms (leukorrhea, haemorrhages, pelvic pain), the lack of diagnosis before the procedure, the lack of information regarding the staging and the grading, as well as the surgical and radiation treatment, there is, above all, controversy regarding the use of chemotherapy, since the low number of patients in the different series does not permit reaching a conclusion.

Gender differences in the pharmacodynamics of barbiturates in rats

There is considerable evidence of gender differences in the pharmacokinetics of numerous drugs, particularly in rodents, but very limited information concerning the effect of gender on pharmacodynamic characteristics (concentration-activity relationships). In this study, heptabarbital or phenobarbital was administered to male and female rats and the concentrations of these drugs in the brain, cerebrospinal fluid and serum at onset or offset of loss of righting reflex were determined. For heptabarbital, offset concentrations were determined in Lewis rats and onset concentrations in Wistar rats. Onset concentrations of phenobarbital were determined in Wistar rats. In all cases, the barbiturate concentrations in males were significantly lower than those in females at the pharmacologic endpoint. The biologic (serum) half-life of heptabarbital is much shorter in males (approximately 10 min) than in females (approximately 90 min) and this pharmacokinetic difference is reflected by the considerably longer duration of effect of the drug in females.

Aspartame and phenylalanine do not enhance theophylline-induced seizures in rats

Oral administration of the artificial sweetener aspartame, 1 g/kg, or of an equimolar dose of its metabolite phenylalanine, to fasted rats 1 hour before slow i.v. infusion of theophylline until the onset of maximal seizures had no significant effect on the total dose and the serum and cerebrospinal fluid concentrations of theophylline at the pharmacologic endpoint. These findings indicate that consumption of aspartame is not a potential risk factor for theophylline-induced neurotoxicity.

Systemic effect of ipecac on acute toxicity of phenobarbital and theophylline in rats

The emetic agent ipecac is widely used for the initial treatment of acute oral drug overdose. Its emetic and gastric evacuative efficacies have been studied extensively but its potential for pharmacologic interactions with various drugs and other possible poisons has not been explored. The purpose of this investigation was to determine if ipecac can alter the acute toxicity of two widely used drugs that act on the central nervous system, phenobarbital and theophylline. Ipecac syrup, 5 ml/kg, was administered by gavage to male Lewis rats either 1 hr before or 15 or 30 min after the start of an iv infusion of phenobarbital or theophylline. Control animals received the syrup vehicle only. Ipecac elicited vomiting-like behavior (frequent, wide opening of the mouth) for more than 1 hr. The drug infusion was stopped immediately after onset of the loss of righting reflex (phenobarbital) or maximal seizures (theophylline). Samples of cerebrospinal fluid, blood (for serum), and the brain were obtained at that time for analysis of drug concentrations. There were no significant differences between control and ipecac-treated animals with respect to the dose requirements and drug concentrations in cerebrospinal fluid, serum, and brain at the respective pharmacologic endpoint. It is concluded that ipecac has no apparent effect on the acute toxicity of phenobarbital and theophylline in rats.

Kinetics of drug action in disease states. XXXII: Effect of experimental hypertension on the pharmacodynamics of phenobarbital in rats

The purpose of this investigation was to determine the effect of experimental hypertension on the concentrations of phenobarbital required to produce a defined hypnotic effect (loss of righting reflex) in adult, female Lewis rats. Hypertension was induced with deoxycorticosterone acetate (DOCA), administered by im injection (first experiment) or by pellet implant (second experiment), and 1% NaCl in the drinking water. There were two control groups: one that received im injections of water or a drug-free pellet implant plus 1% NaCl in the drinking water, the other that received water injections or drug-free pellet implants and no NaCl in the drinking water. These treatments were carried out for 3 months and resulted in appreciable elevation of blood pressure and increased heart weight in the DOCA + NaCl-treated (but not in the NaCl alone) rats. All animals then received an infusion of phenobarbital until onset of loss of righting reflex. The concentrations of phenobarbital in the serum, serum water, brain, and CSF of the hypertensive rats at the pharmacologic endpoint did not differ significantly from corresponding concentrations in the control groups (except for a marginal difference of the drug concentration in serum water between the DOCA pellet group and the drug-free pellet control group). It is concluded that DOCA-induced hypertension has no apparent effect on the sensitivity of the central nervous system to the hypnotic action of a barbiturate in female rats.

Comparative pharmacokinetics of coumarin anticoagulants. XLIX: Nonlinear tissue distribution of S-warfarin in rats

The serum protein binding of the oral anticoagulant drug warfarin varies widely among rats and largely accounts for corresponding variations in the total serum clearance of the drug. The hepatic uptake of warfarin is concentration dependent despite the concentration independence of the free fraction of warfarin in serum over a wide concentration range. This investigation was designed to determine the distribution of the S enantiomer of warfarin in rats as a function of warfarin concentration, free fraction in serum, dose, and time. Two groups of rats, one with relatively low (0.0043) and the other with relatively high (0.0105) average serum free fraction values, were selected from a large number of adult male Sprague-Dawley rats. All animals received an iv injection of S-warfarin, either 0.25 or 1.0 mg/kg, and were sacrificed at intervals over a period of 10 d. Concentrations of S-warfarin in serum, liver, kidneys, muscle, and fat were determined by HPLC. The tissue:serum concentration ratio (T:S) of the drug was highly concentration dependent, but was independent of dose, time, and (except for fat) free fraction in serum. The T:S for fat was higher in animals with the larger serum free fraction values. The T:S of S-warfarin for the liver was greater than 10 at low concentrations and reached a limiting value of 0.25 at relatively high concentrations of the drug. In general, the T:S versus concentration profiles of S-warfarin are consistent with the presence of two classes of binding sites in the tissues, one with very high affinity and low capacity, the other with lower affinity and apparently unlimited capacity under the experimental conditions.(ABSTRACT TRUNCATED AT 250 WORDS)

Relationship between concentration and anticonvulsant effect of phenytoin against electroshock-induced seizures in rats: comparison of sampling sites for concentration determinations

The purpose of this investigation was to determine the optimum sampling site for phenytoin concentration measurements in the context of pharmacodynamic studies of the anticonvulsant effect of phenytoin. Determination of drug concentrations in the serum, serum water, brain, and cerebrospinal fluid (CSF) of rats as a function of time after iv injection of a 6-mg/kg dose revealed a significant disequilibrium between brain and serum water for 15 min and between CSF and serum water for 5 min after injection. The concentrations of phenytoin in serum water 1 min after injection of 3 mg/kg (0.371 +/- 0.054 microgram/mL) and 45 min after injection of 8 mg/kg (0.399 +/- 0.049 microgram/mL) were not significantly different, but drug concentrations in the CSF and brain were appreciably higher after the latter dose. There was no protection against electroshock-induced seizures 1 min after the 3-mg/kg dose, but there was complete protection 45 min after the 8-mg/kg dose. At 15 min after drug injection, phenytoin concentrations in CSF and serum water were essentially identical over a wide concentration range. Fifty female Lewis rats weighing approximately 225 g, that consistently exhibited maximal electroshock-induced seizures in three preliminary trials on separate days, received 1, 2, 4, 6, or 8 mg/kg of phenytoin by iv injection. Electroshock was applied 15 min later, the percentage of animals protected from seizure by each dose was determined, and drug concentrations in serum, serum water, brain, and CSF were measured by gas chromatography. The relationship between anticonvulsant activity and drug concentration could be described by a Hill-type equation.(ABSTRACT TRUNCATED AT 250 WORDS)

Induction of experimental thyroid dysfunction in rats with implantable pellets of thyroxine or propylthiouracil

Subcutaneously implanted pellets containing the thyroid hormone thyroxine or the thyrotoxic agent propylthiouracil were used to induce hyper- or hypothyroidism in rats. The results obtained were compared to those produced by daily subcutaneous injection of these substances. The thyroxine pellets caused substantial elevation of serum thyroxine concentrations for at least 25 days, whereas the propylthiouracil pellets caused a pronounced decrease of serum thyroxine concentrations. Changes in heart weight and rectal temperature were consistent with the observed alterations of serum thyroxine concentrations. Treatment with propylthiouracil was associated with small elevations of serum total protein, urea nitrogen, and creatine concentrations regardless of the method of administration of this agent. It is concluded that implantable pellets are an effective and convenient means of administering drugs for producing thyroid dysfunction in rats.

Kinetics of drug action in disease states. XXXI. Effect of experimental hyperthyroidism on the hypnotic activity of a benzodiazepine (oxazepam) in rats

This investigation was designed to determine the effect of experimental hyperthyroidism on the hypnotic activity of a benzodiazepine and on the binding characteristics of the benzodiazepine receptor complex. Rats were made hyperthyroid by subcutaneous implantation of slow release pellets containing L-thyroxine. This treatment produced the characteristic symptoms of hyperthyroidism: increased serum thyroxine concentrations, increased heart weight and body temperature, and decreased serum protein concentrations. The hyperthyroid rats and a parallel group of normal animals (with drug-free pellets implanted subcutaneously) were slowly infused intravenously with oxazepam until they lost their righting reflex. The hyperthyroid rats required a significantly larger dose of the benzodiazepine and their total serum and cerebrospinal fluid concentrations of oxazepam (but not the serum concentration of free drug and the brain concentration) at the onset of loss of the righting reflex were modestly but statistically significantly lower than those of the normal rats. The receptor density and affinity for diazepam in hyperthyroid rats were not significantly different from those of the normal animals. Hyperthyroidism apparently affects the pharmacokinetics of oxazepam but has, at best, only a small effect on the pharmacodynamics (hypnotic activity) of the drug.

Activation of the immune coagulation system by murine hepatitis virus strain 3

Viral infections result in alterations in hemostasis and coagulation. It has previously been shown that susceptibility to murine hepatitis virus strain 3 (MHV-3), a coronavirus, correlates directly with the spontaneous, T lymphocyte-instructed expression of a procoagulant monokine that exhibits prothrombin-cleaving activity (procoagulant activity [PCA]). A biologic role for PCA in the pathogenesis of MHV-3 infection is suggested by results of in vivo microscopic observations made during acute MHV-3 infection. Recently, it has been demonstrated that prostaglandin E2 abrogates the induction of PCA by MHV-3 both in vivo and in vitro and prevents hepatic necrosis and the associated microcirculatory changes. These data suggest that MHV-3 induces cellular injury through the activation of the coagulation cascade and provide further evidence for a role for PCA in the pathogenesis of MHV-3 infection.

Kinetics of drug action in disease states. XXIX. Effect of experimental nephrotic syndrome on the pharmacodynamics of heptabarbital: implications of severe hypoalbuminemia

The purpose of this investigation was to determine the effect of nephrotic syndrome (NS) on the pharmacodynamics of a barbiturate. NS was induced in male rats by puromycin aminonucleoside; it caused hypoproteinemia, increased liver and kidney weight and elevated serum creatinine and urea nitrogen concentrations. Serum albumin concentration decreased from 3.5% in controls to 0.90% in NS animals. The rats were infused i.v. with heptabarbital, 1 mg/min, until they lost their righting reflex. The total dose (mean +/- S.D.) required by rats with NS, 40.2 +/- 4.2 mg/kg, was substantially lower than that required by normal animals (68.6 +/- 6.2 mg/kg, P less than .001). Serum protein binding of heptabarbital was reduced from 49% in controls to 26% in NS rats. However, the drug concentration in cerebrospinal fluid (CSF) at the pharmacologic endpoint was not significantly different in controls and NS rats (18.9 +/- 1.5 vs. 18.3 +/- 1.4 mg/l). Serum, CSF and the brain contained appreciable concentrations of a metabolite of heptabarbital. To determine if the metabolite contributes to the pharmacologic effect of the parent drug, rats received an i.v. injection of 46, 60 or 100 mg/kg of heptabarbital. Concentrations of heptabarbital in CSF at return of righting reflex (which occurred after 15, 25 and 50 min, respectively) were independent of dose whereas metabolite concentrations increased with increasing dose. Thus, the metabolite of heptabarbital in male rats is pharmacologically inactive.(ABSTRACT TRUNCATED AT 250 WORDS)