Ear temperature measurements in healthy children using the arterial heat balance method

This study was undertaken to determine the upper limit of normal ear temperatures, defined as the 95th percentile for infants, children, and adolescents, using the arterial heat balance method for measuring ear temperatures. Ear temperatures were measured in 62 infants, 0-2 months of age; 346 children, 3-47 months; 226 children, 48-119 months; and 172 adolescents, 120-227 months using the LighTouch Pedi-Q (Exergen Corp, Watertown, MA) ear thermometer. The 95th percentiles for the four age groups were 100.1 degrees F (37.8 degrees C), 100.3 degrees F (37.9 degrees C), 99.8 degrees F (37.7 degrees C), and 99.8 degrees F (37.7 degrees C), respectively. Temperatures above 100.0 degrees F (37.8 degrees C) using the LighTouch Pedi-Q ear thermometer should be considered elevated.

The role of dopamine in the locomotor stimulant effects and tolerance to these effects of caffeine

Current evidence indicates that the acute locomotor stimulant effects of caffeine involve dopamine (DA) receptor activation; however, few studies have investigated the role of DA receptors in mediating the development of tolerance to caffeine. Therefore, the present study was designed to determine the degree to which DA receptors mediate the development of tolerance to the locomotor stimulant effects of caffeine. Caffeine was examined alone and in combination with haloperidol (HAL), GBR 12909, nisoxetine and fluoxetine. HAL dose-dependently and completely blocked the acute effects of caffeine on locomotor activity, and the highest dose of GBR 12909 enhanced the effects of caffeine. Neither nisoxetine nor fluoxetine altered the effects of caffeine. HAL was infused via osmotic pumps (0.1 mg/kg/day) during a 14-day regimen of chronic caffeine administered in a caffeinated drinking solution ( approximately 136 mg/kg/day). HAL did not block the development of tolerance to the locomotor stimulant effects of caffeine, but did impair the recovery from tolerance following withdrawal of caffeine. [3H]SCH 23390 (DA D(1)) binding sites were downregulated in the nucleus accumbens and striatum and were upregulated in the prefrontal cortex of caffeine-treated vs. control rats; however, the affinity of [3H]SCH 23390 for these binding sites was unaltered. There were no differences between the caffeine-treated and control rats in number or affinity of [3H]spiperone (DA D(2)) binding sites. These results suggest that, although HAL did not alter the development of tolerance to caffeine, changes in DA D(1) receptors could be one component of the mechanism underlying caffeine-induced tolerance.

Parametric evaluation of the development of sensitization to the effects of morphine on locomotor activity

Animals repeatedly administered drugs of abuse often become more sensitive to their effects. It has been proposed that this behavioral sensitization may serve as a useful model for changes that may underlie the etiology and maintenance of drug-seeking behavior. This study was designed to determine systematically some of the conditions of drug exposure under which sensitization occurs to morphine-induced stimulation of locomotor activity. Groups of rats (n=8 per group) were exposed to a regimen of intermittent morphine or saline injections for 1--4 days and tested at later time points with morphine or saline. The amount of behavioral sensitization observed was related to the number of drug exposures, but not to the dose of morphine used during drug exposures. Sensitization to morphine persisted for as long as 3 months and was completely blocked when naltrexone was administered with the test dose of morphine after the final morphine exposure. Administration of naltrexone with morphine during the exposure regimen did not alter the development of behavioral sensitization. These results indicate a robust behavioral sensitization to morphine that appears to be influenced in an orderly manner within a narrow window of the drug exposure conditions.

Modulation of the discriminative stimulus effects of d-amphetamine by mu and kappa opioids in squirrel monkeys

It has been reported that the discriminative stimulus effects of cocaine in squirrel monkeys can be potentiated by mu opioid agonists and attenuated by kappa opioid agonists. The purpose of this study was to extend these observations by examining the effects of mu and kappa opioids agonists on the discriminative stimulus effects of d-amphetamine (AMPH). Five squirrel monkeys were trained to discriminate 0.3 mg/kg of AMPH (i.m.) from saline using a stimulus termination/avoidance task. AMPH and cocaine substituted dose dependently for the AMPH training stimulus in all five monkeys. The AMPH training dose was completely antagonized by 0.1 mg/kg of the D1 dopamine antagonist SCH 39166. When administered alone, the kappa agonist U69,593 substituted partially or completely for AMPH in four of five monkeys, the kappa agonist enadoline substituted completely for AMPH in two of five monkeys, and morphine substituted completely for AMPH in one monkey. In all five monkeys, pretreatment with some doses of U69,593 or enadoline attenuated the discriminative stimulus effects of AMPH; however, some doses of U69,593 and enadoline also potentiated the effects of AMPH in at least two monkeys. Morphine pretreatment potentiated the discriminative stimulus effects of AMPH in three monkeys and either attenuated or did not alter these effects in two monkeys. Morphine pretreatment did not significantly alter the discriminative stimulus effects of cocaine except in one monkey. These data indicate large individual differences in the abilities of mu and kappa opioid agonists to alter the discriminative stimulus effects of AMPH.

Differential involvement of dopamine in mediating the discriminative stimulus effects of low and high doses of caffeine in rats

The hypothesis that low and high doses of caffeine produce effects that are differentially mediated by dopamine (DA) receptor mechanisms was investigated in rats trained to discriminate either 10 or 56 mg/kg of caffeine from saline. Rats trained to discriminate 56 mg/kg of caffeine acquired the discrimination in an average of 74 sessions, whereas rats trained to discriminate 10 mg/kg of caffeine required an average of 108 sessions. The DA D1 receptor agonist SKF 81297 and the DA D2 receptor agonist R(-)-propylnorapomorphine (NPA) generalized partially (50-75%) in rats trained to discriminate 10 mg/kg of caffeine, but produced predominantly saline-appropriate responding (< 40%) in rats trained to discriminate 56 mg/kg of caffeine. When SKF 81297 and NPA were combined, stimulus generalization was no greater than it was when either agonist was tested alone. The DA uptake inhibitors cocaine and GBR 12909 produced predominantly saline-appropriate responding in both groups of rats. Neither the DA D1 receptors antagonists SCH 23390 and SCH 31966, nor the DA D2 receptor antagonists eticlopride and sulpiride, generalized in rats trained to discriminate 10 or 56 mg/kg of caffeine. When administered in combination with caffeine, both the DA D1 and DA D2 antagonists antagonized completely the discriminative stimulus effects of the low training dose of caffeine, but did not alter the discriminative stimulus effects of the high training dose. These results suggest that the discriminative stimulus effects of 10 mg/kg of caffeine, but not 56 mg/kg of caffeine, are dependent on, but not limited to, DA D1 and D2 receptor mechanisms.

Comparison of ear to rectal temperature measurements in infants and toddlers

The purpose of this study was to compare arterial heat balance ear temperature measurements to rectal temperatures in infants and children and to determine the ability of the ear thermometer being tested to detect fever. From 12/95 to 2/96, 1,175 pairs of ear and rectal temperature measurements were prospectively obtained from 140 infants and toddlers. The mean rectal temperature was 37.58 degrees C (sd = 0.68) and the mean ear temperature was 37.60 degrees C (sd = 0.85). However, at the low end of the rectal temperature scale, ear temperatures tended to be higher, and at the high end of the rectal temperature scale, ear temperatures tended to be lower. There were 292 readings with a rectal temperature > or = 38.0 degrees C and in 204 (70%) the ear temperature was also > or = 38.0 degrees C. A retrospective analysis of 53 children who became febrile in hospital (ear or rectal temperature > or = 38.0 degrees C) showed that fever was detected first by rectal measurement in seven, by ear measurement in 31 (59%), and by both in 15 (28%). These data indicate that, on the average, rectal and ear temperature measurements are not different. Fever that developed in children after hospitalization was more likely to be first detected by ear than by rectal measurement.

Differential antagonism of the rate-decreasing effects of kappa-opioid receptor agonists by naltrexone and norbinaltorphimine

Eight kappa-opioid receptor agonists were examined for their effects in squirrel monkeys responding under a fixed interval 3-min schedule of stimulus termination. Six of these kappa-opioid receptor agonists decreased dose-dependently the total number of responses and with an order of potency consistent with kappa-opioid receptor interaction. Three of these kappa-opioid receptor agonists, bremazocine, U69,593 [[(5a,7a,8b)-(+)-N-[7-(1-pyrrolidinyl)-1-oxaspiro(4,5)dec-8-yl)] benzeneacetamide] and enadoline, were evaluated following pretreatment with 1.0 mg/kg of naltrexone or 3.0 mg/kg of norbinaltorphimine. The effects of the three agonists were antagonized significantly by naltrexone, but only those of bremazocine and U69,593 were antagonized significantly by norbinaltorphimine. Statistical analysis of the data averaged over six monkeys revealed that naltrexone was significantly more potent than norbinaltorphimine at antagonizing enadoline and U69,593, but naltrexone and norbinaltorphimine were equipotent at antagonizing bremazocine. Moreover, naltrexone was 8-fold more potent at antagonizing U69,593 and enadoline than at antagonizing bremazocine. These results suggest that under these conditions the effects of U69,593 and enadoline may be mediated, in part, by a different receptor population, perhaps a subtype of kappa-opioid receptors, from the one that mediates the effects of bremazocine.

Lack of NMDA receptor involvement in caffeine-induced locomotor stimulation and tolerance in rats

The involvement of NMDA-type glutamate receptors in caffeine's locomotor stimulant effects and the development of tolerance to these effects was examined in rats. Caffeine and the noncompetitive NMDA receptor antagonists, MK-801 and phencyclidine (PCP), were examined alone and in combination. Caffeine produced a biphasic dose-effect curve. Both MK-801 and PCP increased locomotor activity at the highest doses tested. MK-801 and PCP shifted the caffeine curve upward, but only with the highest doses that increased locomotor activity when given alone. For the tolerance experiment, osmotic pumps containing either MK-801 or nothing at all and were implanted in rats that were given either caffeinated or drug-free tap water to drink. All rats drinking caffeine showed tolerance to its locomotor stimulant effects, whereas rats drinking drug-free tap water did not. Chronic infusion of MK-801 (0.1 and 0.3 mg/kg/day) failed to block the development of tolerance to caffeine. The 0.3 mg/kg/day infusion of MK-801 appeared to slightly delay the development of tolerance to caffeine, but this effect was probably due to the locomotor stimulant effects of this infused dose of MK-801 alone. These data provide no evidence that NMDA-type glutamate receptors play a crucial role in mediating caffeine's locomotor stimulant effects or tolerance to these effects.

The role of serotonergic receptors in the effects of mu opioids in squirrel monkeys responding under a titration procedure

This experiment was conducted to determine whether drugs acting on brain serotonin modulate the effects of the mu opioid, morphine, as measured by the squirrel monkey shock titration procedure and, if so, whether serotonergic modulation is mediated via specific 5HT receptor subtypes. Under this procedure, electric shock was delivered to the monkey's tail and scheduled to increase once every 15 s from 0.01 to 2.0 mA in 30 steps. Five responses on a lever during the 15-s shock period terminated the shock for 15 s, after which the shock resumed at the next lower intensity. The intensity below which monkeys maintained shock 50% of the time (median shock level or MSL) and rate of responding (RR) in the presence of shock were determined under control conditions and after administration of morphine alone and in combination with various serotonergic compounds. Morphine increased median shock level and decreased rate of responding in a dose-dependent manner. These effects of morphine was attenuated by the 5HT1A receptor agonists, 8-OH-DPAT [(+)-8-hydroxy-2(di-n-propylamino tetralin HBr] and ipsapirone. The effects of morphine were not altered by the 5HT1A receptor antagonist, NAN-190 [1-(2-methoxyphenyl-4-[4-(2-phthalimido) butyl] piperazine HBr], and 5HT2 receptor antagonist, ketanserin, the 5HT3 receptor antagonist, MDL 72222 [3-tropanyl-3,5-dichlorobenzoate], the alpha 2 adrenergic antagonist, yohimbine, or the alpha2 adrenergic agonist, clonidine. These results suggest that 5HT1A receptors may be involved in the effects of morphine in the shock titration procedure, whereas 5HT2, 5HT3 and alpha 2 adrenergic receptors do not appear to play a role in morphine's effects in this procedure.

The role of serotonin in the effects of opioids in squirrel monkeys responding under a titration procedure: I. Kappa opioids

The goal of the present study was to determine whether the serotonin (5-HT) system is involved in the effects of kappa opioids as measured with the squirrel monkey shock titration procedure. With this procedure, electric shock was delivered to the monkey's tail and scheduled to increase once every 15 sec from 0.01 to 2.0 mA in 30 steps. Monkeys responded under a fixed ratio 5 schedule to determine the level at which shock intensity was maintained. The intensity below which monkeys maintained shock 50% of the time, or the median shock level (MSL), and the rate of responding in the presence of shock (RR) were determined after the administration of saline and all drug combinations. The kappa opioids U50,488 and spiradoline increased MSL and decreased RR in a dose-dependent manner. The effects of U50,488 and spiradoline on both RR and MSL were enhanced in all three monkeys by the 5-HT2 antagonists ketanserin and pirenperone and in one monkey by another 5-HT2 antagonist, LY 53857. The effects of U50,488, but not spiradoline, were enhanced to a lesser degree by the 5-HT1A receptor agonist 8-OH-DPAT. The effects of U50,488 but not altered by the receptor agonist DOI, the 5-HT3 receptor antagonist MDL 72222 or the alpha-1 adrenergic receptor antagonist prazosin. These results suggest that the effects of kappa opioids in the shock titration procedure probably involve serotonergic mechanisms that are modulated via 5-HT2 and, perhaps, 5-HT1A receptors. Moreover, these interactions probably reflect nonspecific decreases in RR rather than alterations in the antinociceptive effects of kappa opioids.

Febrile infants at low risk for serious bacterial infection--an appraisal of the Rochester criteria and implications for management. Febrile Infant Collaborative Study Group

OBJECTIVE

Prospective studies were conducted to test the hypothesis that infants unlikely to have serious bacterial infections (SBI) can be accurately identified by low risk criteria.

METHODS

Febrile infants (rectal T > or = 38 degrees C) < or = 60 days of age were considered at low risk for SBI if they met the following criteria: 1) appear well; 2) were previously healthy; 3) have no focal infection; 4) have WBC count 5.0-15.0 x 10(9) cells/L (5000-15,000/mm3), band form count < or = 1.5 x 10(9) cells/L (< or = 1500/mm3), < or = 10 WBC per high power field on microscopic examination of spun urine sediment, and < or = 5 WBC per high power field on microscopic examination of a stool smear (if diarrhea). The recommended evaluation included the culture of specimens of blood, cerebrospinal fluid, and urine for bacteria. Outcomes were determined. The negative predictive values of the low risk criteria for SBI and bacteremia were calculated.

RESULTS

Of 1057 eligible infants, 931 were well appearing, and, of these, 437 met the remaining low risk criteria. Five low risk infants had SBI including two infants with bacteremia. The negative predictive value of the low risk criteria was 98.9% (95% confidence interval, 97.2% to 99.6%) for SBI, and 99.5% (95% confidence interval, 98.2% to 99.9%) for bacteremia.

CONCLUSIONS

These data confirm the ability of the low risk criteria to identify infants unlikely to have SBI. Infants who meet the low risk criteria can be carefully observed without administering antimicrobial agents.

Prevention of central venous catheter-related coagulase-negative staphylococcal sepsis in neonates

A randomized, double-blind, controlled trial was conducted to determine whether vancomycin added to parenteral alimentation solution given via a central venous catheter would decrease the incidence of catheter-related coagulase-negative staphylococcal sepsis. Seventy infants with a central venous catheter (CVC) in place were randomly selected to receive total parenteral nutrition--either the standard solution or a solution containing 25 micrograms of vancomycin per milliliter. Catheter-related sepsis was defined as the isolation of the same bacterial species from specimens of both peripheral and CVC blood with the concentration of bacteria at least tenfold greater in the specimen obtained from the CVC. Specimens from the CVCs were cultured on removal of the catheters to determine colonization. The colonization of catheters by coagulase-negative staphylococci was reduced from 40% to 22% (p = 0.03) in the vancomycin group; catheter-related sepsis was reduced from 15% to no cases (p = 0.004). Fewer infants required CVC reinsertion in the vancomycin-treated group (p = 0.02), who also regained birth weight earlier (13.4 vs 17.1 days (p = 0.014)). Adverse effects of vancomycin infusion were not observed. We conclude that vancomycin added to the solution used for total parenteral nutrition effectively reduces catheter-related sepsis in the neonatal intensive care unit and offers other potential benefits such as the need for fewer catheters and earlier weight gain. However, we do not recommend widespread implementation of this technique until there are data regarding the emergence of vancomycin-resistant organisms.

Practice guideline for the management of infants and children 0 to 36 months of age with fever without source. Agency for Health Care Policy and Research

STUDY OBJECTIVE

To develop guidelines for the care of infants and children from birth to 36 months of age with fever without source.

PARTICIPANTS AND SETTING

An expert panel of senior academic faculty with expertise in pediatrics and infectious diseases or emergency medicine.

DESIGN AND INTERVENTION

A comprehensive literature search was used to identify all publications pertinent to the management of the febrile child. When appropriate, meta-analysis was used to combine the results of multiple studies. One or more specific management strategies were proposed for each of the decision nodes in draft management algorithms. The draft algorithms, selected publications, and the meta-analyses were provided to the panel, which determined the final guidelines using the modified Delphi technique.

RESULTS

All toxic-appearing infants and children and all febrile infants less than 28 days of age should be hospitalized for parenteral antibiotic therapy. Febrile infants 28 to 90 days of age defined at low risk by specific clinical and laboratory criteria may be managed as outpatients if close follow-up is assured. Older children with fever less than 39.0 C without source need no laboratory tests or antibiotics. Children 3 to 36 months of age with fever of 39.0 C or more and whose WBC count is 15,000/mm3 or more should have a blood culture and be treated with antibiotics pending culture results. Urine cultures should be obtained from all boys 6 months of age or less and all girls 2 years of age or less who are treated with antibiotics.

CONCLUSION

These guidelines do not eliminate all risk or strictly confine antibiotic treatment to children likely to have occult bacteremia. Physicians may individualize therapy based on clinical circumstances or adopt a variation of these guidelines based on a different interpretation of the evidence.

Two-component arterial blood pressure conditional response in rat

The objective of these experiments was to quantify the pattern of change in arterial blood pressure (BP) during a discriminative aversive classical conditioning paradigm in rat using a new "high resolution" computer analysis. Sprague-Dawley rats (n = 5) were restrained in a soft, conical cloth pouch and conditioned using a 6 sec. pulsed tone (CS+) followed by a 0.5 sec. tail shock; a steady tone, never followed by shock, served as a CS-. BP peaked at 16.4 +/- 6.5 mm Hg (mean +/- SD) above control at 1.5 +/- 0.1 sec. after onset of CS+. This "first component" ("C1") also occurred during CS- (12.1 +/- 3.8 mm Hg), although the magnitudes of the two were significantly (p < 0.05) different. Another group of rats (n = 8) was treated identically except the tones were 15 seconds long. The conditional BP response consisted of two components. C1 was reminiscent of that seen using the short tone: for CS+ a peak of 13.6 +/- 5.6 mm Hg at 1.5 sec. or, for CS-, of 10.0 +/- 4.3 at 1.3 sec. (p < 0.05). In CS+ trials BP peaked again ("C2," 7.4 +/- 2.5 mm Hg) at 8.3 +/- 1.2 sec. There was no statistically significant C2 for CS- trials, clearly demonstrating discrimination between tones. The unconditional BP response in both groups consisted of two large, closely spaced peaks in BP. Respiration was recorded in 3 additional rats. After shock delivery these subjects often showed a sudden shift between (1) a regular respiratory pattern with moderate chest excursion and (2) apneic episodes interspersed with single, deep breaths. This latter pattern was associated with large, low frequency fluctuations in BP. Continued development of the rat conditioning paradigm is especially warranted because of the ability to record sympathetic nerve activity in intact, awake subjects and the large number of readily available genetic strains, which model human pathological states.

Antinociceptive effects of the kappa opioid, U50,488: lack of modulation by 5-HT2 antagonists

The kappa opioid, U50,488, was examined alone and in combination with the 5HT2 antagonists, ketanserin, pirenperone and LY 53857. Squirrel monkeys responded under a shock titration procedure in which shock intensity increased every 15 s from 0.01 to 2.0 mA in 30 steps. Five responses terminated the shock for 15 s, after which the shock resumed at the next lower intensity. The level at which the monkeys kept the shock 50% of the time (median shock level/MSL) was determined. U50,488 alone produced dose-dependent increases in median shock level whereas none of the 5-HT2 antagonists altered responding under this procedure. When ketanserin (0.032-5.6 mg/kg) was administered in combination with U50,488, very high doses of ketanserin (3.2-5.6 mg/kg) shifted the U50,488 dose-effect curve to the left. Neither pirenperone (0.032-10.0 micrograms/kg) nor LY53857 (0.01-0.32 mg/kg) altered the U50,488 dose-effect curve in any monkey. Taken together, these data do not support a role for the 5-HT2 system in kappa-induced antinociception in the primate.

Intermediate efficacy mu opioids: examination of their morphine-like stimulus effects and response rate-decreasing effects in morphine-tolerant rats

The present study examined the effects of morphine, the intermediate efficacy mu opioids (-)-pentazocine, (-)-metazocine, proxorphan, levallorphan, (-)-NANMY (N-allylnormetazocine) and (-)-cyclazocine, and the mu antagonist naloxone 1) in rats responding under a FR (fixed-ratio) 30 schedule before, during and after a chronic morphine regimen, and 2) in rats trained to discriminate 10.0 [10-MS (morphine sulfate)] or 3.0 mg/kg (3-MS) of morphine from saline. Under the FR30 schedule, chronic administration of morphine produced tolerance to morphine's rate-decreasing effects and conferred cross-tolerance to (-)-metazocine, proxorphan and (-)-pentazocine. However, the effects of these intermediate efficacy mu opioids could be differentiated from those of morphine on the basis of their 1) shallow dose-effect curves, and 2) large differences in the degree to which tolerance developed in individual rats. In the drug discrimination procedure, (-)-metazocine, proxorphan and (-)-pentazocine produced high levels of substitution for the 3-MS stimulus and intermediate levels for the 10-MS stimulus. In contrast to the pattern of substitution observed with morphine in the 10-MS group, the effects of these drugs were characterized by 1) shallow dose-effect curves, 2) large individual differences in the lowest dose of each drug that substituted completely for the 10-MS stimulus and 3) the failure to obtain complete substitution for the 10-MS stimulus in all of the rats tested. The behavioral profile obtained with the intermediate efficacy mu opioids (-)-NANM, levallorphan and (-)-cyclazocine was indicative of opioids with intrinsic efficacy lower than that of (-)-pentazocine, (-)-metazocine and proxorphan. Under the FR30 schedule, chronic administration of morphine produced an enhanced sensitivity to the rate-decreasing effects of (-)-NANM and levallorphan but not (-)-cyclazocine. In the drug discrimination procedure, (-)-NANM, levallorphan and (-)-cyclazocine produced high levels of substitution for the 3-MS stimulus and low levels for the 10-MS stimulus. Like naloxone, these drugs produced a dose-related attenuation of the 10-MS stimulus. The results of the present study suggest that the relative order of intrinsic efficacy among the opioids tested is: morphine > (-)-metazocine = (-)-pentazocine = proxorphan > (-)-cyclazocine = levallorphan = (-)-NANM > naloxone.

Hemolytic uremic syndrome due to Escherichia coli O157: H7 in a child with multiple infections

Hemolytic uremic syndrome (HUS) is characterized by hemolytic anemia, thrombocytopenia, and uremia; it is a common cause of acute renal failure in children. Although many microbial agents have been associated with HUS, only Escherichia coli O157: H7 has been clearly demonstrated to be a major cause of this illness. A case is presented of a healthy 4-year-old boy who had a recent varicella infection; when evaluated for HUS his blood and stool cultures both grew Salmonella montevideo and blood cultures grew group A beta-hemolytic streptococci. A stool cultured on MacConkey-sorbitol agar also grew E. coli O157: H7. An eightfold rise in serum antibodies to E. coli O157: H7 lipopolysaccharide was also demonstrated. The child recovered completely and was healthy 3 years later. Although this child had several infectious agents anecdotally associated with HUS, appropriate culture of stool showed that he also had E. coli O157: H7 infection. Previous cases thought to be due to other pathogens may similarly have been caused by co-infection with E. coli O157: H7.

The changing spectrum of group B streptococcal disease in infants: an eleven-year experience in a tertiary care hospital

Risk factors, clinical syndromes and the case-fatality rates associated with Group B Streptococcus (GBS) infections in infants managed at the University of Rochester Medical Center during 1979 to 1989 were reviewed. Overall 92 episodes of early onset disease (EOD) and 54 of late onset disease (LOD) were diagnosed in 143 infants (3 infants with EOD presented later with LOD). About one-third of patients with EOD and controls were non-white compared with two-thirds of patients with LOD that occurred in racial minority groups. Prematurity and low birth weight were significantly more common in patients with invasive GBS disease than in controls. Eighty-three of 92 (90%) cases of EOD were detected during the first day of life and 10 of 54 (19%) cases of LOD occurred in infants older than 3 months of age. At the time of diagnosis 4% of infants with EOD were asymptomatic, 54% had respiratory disease, 27% had sepsis without a focus, 15% had meningitis and 1% had urinary tract infection or omphalitis. Among infants with LOD 46% had sepsis, 37% meningitis, 7% urinary tract infection, 6% osteomyelitis and/or septic arthritis and 4% cellulitis or pneumonia. Leukopenia and shift to the left were observed in 43 and 61% of episodes of EOD and in 28 and 57% of episodes of LOD, respectively. All infants were promptly treated with antibiotics and vigorous supportive therapy. The case-fatality rate was 13% in EOD and 0 in LOD.(ABSTRACT TRUNCATED AT 250 WORDS)

Relevance of common tests of cerebrospinal fluid in screening for bacterial meningitis

This study tests the hypothesis that if cerebrospinal fluid (CSF) has a nucleated blood cell count (NucBC) of less than 6/mm3, CSF tests other than bacterial culture need not be performed to exclude the diagnosis of bacterial meningitis in patients not receiving antimicrobial agents. The results of tests performed on the first specimen of CSF obtained for a given hospital visit from children younger than 3 years of age, exclusive of newborn infants admitted to the hospital on their date of birth, were analyzed. Of 3356 CSF specimens evaluated, 122 were from patients with bacterial meningitis; 460 specimens were analyzed separately because the erythrocyte count was greater than 1000/mm3. A negative CSF screening test result was defined as a CSF NucBC less than 6/mm3. In facilitating the diagnosis of bacterial meningitis, this screening test had a sensitivity of 98.4%, a specificity of 75.2%, and a negative predictive value of 99.9%. The other CSF tests varied widely in screening effectiveness: a Gram-stained smear had a sensitivity of 53% and a specificity of 97%. Receiver operating characteristic curve analysis was used to assess the screening relevance of CSF tests. The CSF NucBC and CSF segmented NucBC performed indistinguishably and superiorly compared with the CSF protein or glucose concentration and the ratio of CSF glucose to serum glucose concentration. Logistic regression analysis showed that the NucBC alone is superior to any combination of the other CSF tests. In a prospective study of 215 children younger than 3 years of age undergoing a lumbar puncture in our emergency department, 85% had empiric criteria identifying them as appropriate for an abbreviated CSF evaluation. The CSF NucBC was less than 6/mm3 in 70% of the 181 patients who would have been eligible for an abbreviated CSF evaluation. These data suggest that a strategy for the sequential testing of CSF could be adopted that would exclude unnecessary determinations and thereby save time, effort, and health care dollars.

Evaluation of the effects of PD 134308 (CI-988), a CCK-B antagonist, on the punished responding of squirrel monkeys

Lever pressing of squirrel monkeys was maintained by a fixed-interval 3-min schedule of food presentation during which every 30th response also produced a brief electric shock. Lever pressing was suppressed during this stimulus (conflict or punishment) compared to that occurring prior to the introduction of shock or, with some monkeys, during an alternate stimulus in which punishment did not occur. PD 134308 (CI-988), administered i.m. (0.03-3.0 mg/kg), increased punished responding but had no effect on non-punished responding. Peak increases of 150% of control occurred at 3.0 mg/kg. There was no indication of sedation at the highest dose of PD 134308 (10.0 mg/kg). By comparison, chlordiazepoxide (1.0-10 mg/kg, i.m.) produced similar effects, except the magnitude of increases in punished responding reached approximately 200% of control performance levels and the higher doses reduced non-punished response rates. PD 134308 produces anxiolytic-like effects in this animal model of anxiety that would suggest potential clinical efficacy in humans of a novel class of compounds with actions at or modulated by cholecystokinin receptors.

Autoradiographic analysis of the in vivo distribution of 3H-imipramine and 3H-desipramine in brain: comparison to in vitro binding patterns

Using high resolution autoradiographic techniques, the distribution of radioactivity in forebrain and brainstem was assessed after IV injection of 3H-impramine or 3H-desipramine. Results were compared with regional binding of the drugs to brain sections in vitro. Similar topographic binding of 3H-imipramine and 3H-desipramine was observed in vitro among brain regions, except in the paraventricular nucleus of the hypothalamus and locus coeruleus, where binding was greater for 3H-desipramine. For both 3H-desipramine and 3H-imipramine, some brain regions that exhibited high binding in vitro also showed high accumulation after in vivo injection. However, certain regions that contained high densities of binding sites for the antidepressant drugs as measured by in vitro binding showed very low accumulation of radioactivity after in vivo treatment. Such regions included the dentate gyrus of the hippocampus, layer 1 of piriform cortex, caudate-putamen, pontine and midbrain central gray, and cerebellar granular layer. Compared to in vitro binding of the drugs, the distribution of imipramine and desipramine in vivo appears more anatomically selective. For imipramine, primary sites of action in vivo, as indicated by the topographic distribution in brain, appear to be the locus coeruleus, hippocampus, lateral septal nucleus, and amygdala. For desipramine, the greatest accumulation in vivo was found in the locus coeruleus, paraventricular nucleus of the hypothalamus, and anterior thalamic nuclei.

Differential cross-tolerance to mu and kappa opioid agonists in morphine-tolerant rats responding under a schedule of food presentation

If different populations of opioid receptors mediate the actions of mu and kappa opioid agonists, then tolerance induced by the chronic administration of a mu agonist should confer cross-tolerance to other mu agonists but not necessarily to those compounds whose effects are mediated by the kappa receptor. This hypothesis was evaluated in the present investigation by examining the effects of the mu agonists morphine, l-methadone and fentanyl, the kappa agonists U50,488 and bremazocine, and the mixed kappa/mu agonist ethylketocyclazocine in rats responding under a fixed-ratio 30 schedule of food presentation before, during and after exposure to a regimen of chronic morphine administration. For comparison, naloxone was evaluated as a representative mu antagonist and the phenothiazine chlorpromazine as a control drug. During all phases of the experiment, each of these compounds produced dose-related decreases in rate of responding. During the daily administration of 40 mg/kg morphine, tolerance developed to the rate-decreasing effects of morphine, l-methadone and fentanyl, and an enhanced sensitivity to the effects of naloxone. In contrast to the effects obtained with these mu opioids, there was no evidence that chronic morphine administration produced tolerance or enhanced sensitivity to the rate-decreasing effects of U50,488, bremazocine, ethylketocyclazocine and chlorpromazine. The present findings demonstrate that the chronic administration of morphine results in the selective development of tolerance to other mu agonists.(ABSTRACT TRUNCATED AT 250 WORDS)

Normalization of plasma arginine vasopressin concentrations when children with meningitis are given maintenance plus replacement fluid therapy

We hypothesized that plasma arginine vasopressin (AVP) concentrations in children with meningitis are appropriate for the children's degree of hypovolemia, even though the concentrations were higher than expected for the serum osmolality. A randomized study was conducted to compare the effect on plasma AVP concentrations of giving maintenance fluid requirements plus replacement of any deficit versus restricting fluids to two thirds of maintenance requirements for 24 hours. Plasma AVP concentrations and serum osmolality were measured before fluid therapy was begun and again after 24 hours. Nineteen children, 2 months to 17 years of age, were studied; 13 had bacterial meningitis (12 with Haemophilus influenzae type b). Ten children (seven with bacterial meningitis) received a mean of 1.42 times the calculated maintenance fluid requirements, and nine (six with bacterial meningitis) were restricted to a mean of 0.65 times maintenance. Children in the maintenance group also received significantly more sodium (mean = 6.3 mEq/kg/24 hr) than children in the fluid-restricted group (mean = 2.0 mEq/kg/24 hr). The two groups were comparable for plasma AVP concentration and serum osmolality before fluid therapy was begun. The plasma AVP concentration was significantly lower after 24 hours of maintenance plus replacement fluids than after fluid restriction (p = 0.005), and the change in AVP concentration correlated with the amount of sodium given (p less than 0.02). This study supports the hypothesis that serum AVP concentrations are elevated in patients with meningitis because of hypovolemia and become normal when sufficient sodium is given to facilitate reabsorption of water by the proximal tubule of the kidney. Patients with meningitis can be given maintenance plus replacement fluids but should be monitored for the development of the syndrome of inappropriate secretion of antidiuretic hormone.

Outpatient management of selected infants younger than two months of age evaluated for possible sepsis

Previously healthy infants younger than 2 months of age without evidence of soft tissue or musculoskeletal infection who had white blood cell counts between 5000 and 15,000/mm3, band form counts less than or equal to 1500/mm3, urinalysis less than or equal to 10 white blood cells/high power field (spun sediment) and stool less than or equal to 5 white blood cells/high power field (if diarrhea) were considered at low risk for a serious bacterial infection. Infants meeting these criteria whose parents were judged to be adequate observers and had a telephone and automobile were eligible for outpatient management. Infants were given ceftriaxone to cover the possibility that the low risk criteria might miss more infants with serious bacterial infections than was predicted. From Jan. 1, 1987 to May 31, 1989, 86 infants younger than 2 months were enrolled. There were no serious complications in these infants. Twelve had transient problems possibly related to the intramuscular ceftriaxone therapy. One low risk infant was hospitalized for Neisseria meningitidis bacteremia and five other infants were hospitalized for medical or social reasons. All six hospitalized infants had short admissions and did well. This study supports the continued use of the low risk criteria to distinguish infants unlikely to have a serious bacterial infection. Furthermore, in a selected group of low risk infants, outpatient management may be an acceptable alternative to inpatient therapy.

Epidemiology and laboratory diagnosis of infection with viral and bacterial pathogens in infants hospitalized for suspected sepsis

A prospective study was conducted to determine the frequency and distribution of bacterial and viral pathogens in infants hospitalized with suspected sepsis and to evaluate the potential of virus detection for improving patient management. A causative organism was detected in 157 (67%) of 233 previously healthy infants less than 3 months of age, who had been hospitalized for suspected sepsis: 19 (8%) had bacterial infections, 135 (58%) had viral infections, and 3 (1%) had mixed viral-bacterial infections. Viral infections occurred in a seasonal pattern: enteroviruses were responsible for most of the hospitalizations during summer and fall (65/110; 63%) and respiratory syncytial and influenza A viruses were responsible for most of the infections during winter (44/81; 55%). In contrast, bacterial infections were not seasonally distributed. Virus was detected in 33% of the 138 infected infants within 24 hours, and in 64% within 3 days. We conclude that viral infections are prevalent among infants hospitalized for suspected sepsis, and most can be detected early enough to influence patient management.

Neuroanatomically selective down-regulation of beta adrenergic receptors by chronic imipramine treatment: relationships to the topography of [3H]imipramine and [3H] desipramine binding sites

The down-regulation of beta adrenergic receptors by chronic imipramine treatment was investigated with high resolution autoradiography of [125I]pindolol binding to brain sections. Neuroanatomically selective down-regulation of [125I]pindolol binding was found after chronic imipramine treatment. Subdivisions of the amygdala and hippocampus and discrete cortical regions were differentially affected. In the hippocampus, reduction of [125I]pindolol binding was observed in imipramine-treated rats in the CA-1 stratum radiatum and dentate molecular layer, but not in the CA-3 stratum radiatum. In the amygdala, the basolateral nucleus exhibited reduced [125I]pindolol binding after imipramine treatment but the central and medial nuclei were not affected. Chronic imipramine treatment was also associated with reduced [125I]pindolol binding in layer 1 of the cingulate cortex and layer 3 of the piriform cortex. In contrast, no effect on [125I]pindolol binding was apparent in the ventrolateral thalamic nucleus, caudate-putamen, lateral hypothalamus or layers 2 and 3 of the somatosensory cortex. In order to determine if regional variation in binding sites for imipramine, or its pharmacologically active metabolite desipramine, was responsible for the observed neuroanatomically selective reduction in [125I]pindolol binding, the binding of [3H]imipramine and [3H]desipramine was investigated. In some brain regions that exhibited high densities of [3H]imipramine and [3H]desipramine binding sites, [125I]pindolol binding was reduced after chronic treatment with imipramine. However, other regions that contained high densities of binding sites for antidepressant drugs did not show a reduction in [125I]pindolol binding after chronic imipramine treatment. Thus, regional binding of [3H]imipramine or [3H]desipramine cannot fully explain the neuroanatomical specificity of imipramine-induced beta adrenergic receptor down-regulation.(ABSTRACT TRUNCATED AT 250 WORDS)

Regionally specific neural adaptation of beta adrenergic and 5-hydroxytryptamine2 receptors after antidepressant administration in the forced swim test and after chronic antidepressant drug treatment

In the present investigation, experiments were performed in order to determine whether antidepressants are capable of inducing regionally specific adaptation of beta adrenergic and 5-hydroxytryptamine2 (5-HT2) receptors after chronic administration or when combined with the forced swim test. The drugs tested were imipramine, amitriptyline, pargyline and nomifensine. The regional pattern of beta adrenergic or 5-HT2 receptor binding changes induced after chronic treatment with these antidepressants was not uniform. All of the drugs reduced [3H]dihydroalprenolol binding to cortical membranes after chronic treatment but only two, imipramine and pargyline, did so in hippocampus. All of the antidepressants reduced cortical, but not hippocampal, beta adrenergic receptor binding after 2 days of treatment, indicating that the rate of antidepressant-induced neural adaptation is regionally specific. All of the drugs, except nomifensine, induced down regulation of both cortical and hippocampal 5-HT2 receptors after chronic treatment, as measured by [3H]ketanserin binding. The forced swim test accelerated the reduction of [3H] dihydroalprenolol binding in hippocampus induced by imipramine and pargyline while producing no further effect on cortical beta adrenergic receptors. The down-regulation of hippocampal, but not cortical 5-HT2 receptors by imipramine and pargyline was also facilitated in rats processed in the forced swim test. These results provide further support for the view that the forced swim antidepressant drug screen may be of heuristic value as a model of the adaptive neural mechanisms that accompany chronic antidepressant drug treatment. Furthermore, these data provide evidence that multiple neural mechanisms may be involved in the adaptive changes after antidepressant drug treatment.

Periorbital cellulitis. Clinical and laboratory findings in 146 episodes, including tear countercurrent immunoelectrophoresis in 89 episodes

Medical records of 144 children hospitalized for 146 episodes of periorbital cellulitis were reviewed. During 44 episodes, systemically administered antibiotics were given before hospitalization. Bacterial pathogens were isolated in only two (5%) of 44 episodes in pretreated patients compared with 33 (32%) of 102 episodes in patients who were not pretreated. Thirty-one children who were not pretreated were bacteremic. Compared with nonbacteremic children who were not pretreated, bacteremic children were younger, more often had a history of upper respiratory tract infection and fever, had a higher white blood cell count and temperature at admission, and more often had a violaceous cellulitis. No difference between groups existed in the frequency of a history of trauma or a local lesion near the affected eye. Tear specimens from 13 of 89 children tested by countercurrent immunoelectrophoresis (CIE) to detect Haemophilus influenzae type b capsular polysaccharide were positive. Compared with positive blood culture results, tear CIE has a sensitivity of 50% and a specificity of 93%. Streptococcus pneumoniae infections were not detected by CIE.

Risk of secondary bacterial infection in infants hospitalized with respiratory syncytial viral infection

Because infants hospitalized with respiratory syncytial virus (RSV) infection frequently receive antibiotics, our study was undertaken to determine what the actual risk of secondary bacterial infections in patients with RSV infection is and what effect antibiotic treatment might have on the course of illness. In a 9-year prospective study of 1706 children hospitalized with acute respiratory illnesses, 565 children had documented RSV infections. A subsequent bacterial infection rarely developed in those with RSV lower respiratory tract disease. The rate of subsequent bacterial infection was 1.2% in the total group of children infected with RSV, and 0.6% in the 352 children who received no antibiotics. A significantly greater proportion (4.5%) of subsequent bacterial infections occurred in infants who received parenteral antibiotics (p = 0.01), and especially in a subgroup who received parenteral antibiotics for 5 or more days (11%, p less than 0.001). We conclude that the risk of secondary bacterial infection appears to be low for most infants with RSV infection. In a few infants given parenteral broad-spectrum antibiotics the risk may be greater, but whether this is related to the antibiotic therapy or to other risk factors is not clear.