Significance of blood pressure in infancy. Familial aggregation and predictive effect on later blood pressure.

Blood pressure was measured in 730 infants and their mothers within 5 days of birth. Paternal blood pressures were obtained where possible, and follow-up measurements were made on participants at 1 week and 1, 6, 12, 18, and 24 months. Infant blood pressures were adjusted for such variables as age, observer, cuff size, and sleep/activity status. Infant blood pressure correlated with maternal blood pressure corrected for age and observer shortly after birth (r = 0.138, p less than 0.001 for systolic pressure; r = 0.169, p less than 0.001 for diastolic pressure). Father-infant correlations were significant only at 1 month after birth (r = 0.179, p = 0.031; r = 0.250, p = 0.002 for systolic and diastolic pressures respectively), and sibling correlations were significant from 6 months after birth (r = 0.173, p = 0.011 for systolic pressure; r = 0.265, p less than 0.001 for diastolic pressure). Blood pressures of infants before 6 months after birth were not consistently predictive of later pressures, but systolic and diastolic blood pressures 6 and 12 months after birth were significantly and positively related to pressures at later ages (for systolic pressures at 6 and 12 months, r = 0.147, p = 0.003; 6 and 18 months, r = 0.218, p less than 0.001; 6 and 24 months, r = 0.212, p less than 0.001). These results indicate that the familial aggregation of blood pressure and blood pressure tracking can be detected early in life.

Maternal prenatal dietary potassium, calcium, magnesium, and infant blood pressure.

We studied the association between the prenatal diets of 212 mothers assessed by a semiquantitative food frequency questionnaire and the blood pressure of their infants. Prenatal potassium, calcium, and magnesium intakes were measured and adjusted for total caloric intake. Infant blood pressure was measured at 2-3 days and at 1, 6, and 12 months of age by using an ultrasonic-auscultatory device and was adjusted for cuff size, observer, and sleep/activity status, age in days in neonates, and weight at 6 and 12 months. Maternal prenatal potassium intake was inversely related to diastolic pressure at 6 months (r = -0.28, p less than 0.01) and at 12 months (r = -0.30, p less than 0.05). After adjustment for neonatal breast versus formula feeding, maternal prenatal calcium intake was inversely related to systolic blood pressure at 1 month (r = -0.21, p less than 0.01), and to diastolic blood pressure at 6 months (r = -0.27, p less than 0.01) and 12 months (r = -0.24, p less than 0.05). Maternal prenatal magnesium intake was inversely related to 6-month systolic blood pressure (r = -0.20, p less than 0.05). In multivariable models with all three cations, maternal prenatal potassium intake was independently and inversely related to diastolic blood pressure at 6 and 12 months. Maternal prenatal calcium intake was independently related to 1-month systolic and 6-month diastolic blood pressure. Age-specific infant blood pressure differences between the upper and lower quartiles of maternal prenatal cation intakes ranged from 3 to 7 mm Hg.(ABSTRACT TRUNCATED AT 250 WORDS)

Factors affecting blood pressures in newborn infants.

Blood pressure (BP) was measured in 837 newborn infants ranging in age from 1-6 days and their mothers in Boston, Massachusetts, and Providence, Rhode Island. The BP increased significantly with age in days, birth weight, weight on day of measurement, arm circumference, and ponderal index. There was no relation of sex, race, pulse rate, type of feeding, or Apgar scores to BP in the neonatal period. Significant correlation was found between maternal and infant BP (r = 0.196 for systolic (SBP) and 0.157 for diastolic (DBP) pressures, p < 0.001). Preliminary analysis shows a trend for resemblance of 1-month and newborn BP.

Review of amikacin usage in the EORTC trials.

Four trials have been conducted by the European Organization for Research and Treatment of Cancer's International Antimicrobial Therapy Project Group. These studies involve the randomized assignment of febrile neutropenic patients to receive various antibiotic combinations. The past three trials have utilized amikacin in combination with a variety of beta-lactam antibiotics to provide activity against the most commonly isolated pathogenic bacteria in this clinical setting. Amikacin in combination with expanded-spectrum beta-lactam agents is likely to remain useful in treating infections in granulocytopenic patients.

In vitro models in the study of antibiotic therapy of infections in neutropenic patients.

Most conventional methods for in vitro testing of antibiotics involve exposure of a bacterial inoculum to a constant, static concentration of drug. The in vivo concentrations of antibiotics change continually according to their pharmacokinetics. When two drugs are used, the ratios of their concentrations also change with time. The usual checkerboard tests for combined activity of two or more antibiotics do not consider the pharmacokinetic properties. An in vitro two-compartment pharmacokinetic model has been developed that presents changing concentrations of one or two antibiotics to isolated bacterial inocula. This model simulates the treatment of a bacterial infection in the absence of host defenses and thus mimics infection in a neutropenic patient. This model has been used to study the synergistic activity of beta-lactam/aminoglycoside combinations compared with conventional checkerboard and time-kill methods. Also, in this model, the addition of azlocillin or ceftazidime to netilmicin prevented the selection of resistant subpopulations of Pseudomonas aeruginosa that occurred with the aminoglycoside alone. In vitro pharmacokinetic models add kinetic parameters to conventional susceptibility testing and may prove useful in the design of trials of the optimal dosing and administration of antibiotics for infected neutropenic patients.

Laboratory support for choosing and monitoring antimicrobial therapy in severely ill patients.

The microbiology laboratory plays an important role both in choosing initial antimicrobial therapy and in monitoring such therapy during the course of treatment. In septicemic patients who have few, if any, clinical findings suggesting a specific etiologic diagnosis, it is useful to know the antibiotic susceptibility patterns for the given hospital or community. This type of empiric approach to therapy might require a larger variety of antibiotics than that usually considered for treatment of infected neutropenic patients. In the absence of neutropenia, there is perhaps more latitude in the initial choice, and single-drug therapy often can be considered. While patients are receiving antibiotics that should be appropriate for an identified pathogen, several laboratory procedures can be used to monitor this treatment. Antibiotic synergism studies may be useful in neutropenic patients, as well as assays of serum bactericidal activity. The serum bactericidal activity may be useful also in monitoring therapy for bacterial endocarditis or for osteomyelitis, especially when oral or home therapy is considered. Similarly, drug levels may be measured by a variety of techniques to ensure appropriate serum concentrations and to minimize drug toxicity. In addition, the preclinical evaluation of antibiotics alone and in combination can be used in guiding the design of clinical studies of these drugs in certain patient groups, such as neutropenic patients.

In vitro models for the study of combination antibiotic therapy in neutropenic patients.

Neutropenic patients are at risk of serious infection caused by gram-negative bacilli and staphylococci. The mortality rate associated with gram-negative bacteremia in these patients is extremely high, especially in those with persistent and profound granulocytopenia. In these latter patients, the best results have been obtained by administering combinations of antibiotics in which both agents are active and/or show in vitro synergism against the infecting organism. Most combinations include an aminoglycoside such as amikacin and a broad-spectrum beta-lactam antibiotic, such as azlocillin, mezlocillin, piperacillin, or ceftazidime. The International Antimicrobial Therapy Project Group of the European Organization for Research and Treatment of Cancer has completed several studies evaluating various antibiotic combinations in the empiric treatment of febrile neutropenic patients. These trials have evaluated cephalothin plus gentamicin, carbenicillin plus gentamicin, and cephalothin plus carbenicillin; carbenicillin plus amikacin and carbenicillin plus amikacin plus cefazolin; azlocillin plus amikacin, ticarcillin plus amikacin, and cefotaxime plus amikacin; and azlocillin plus amikacin versus ceftazidime plus long- or short-course amikacin. The preclinical evaluation of antibiotic combinations usually involves the in vitro testing of antibiotics alone and in combination by the checkerboard method or with the use of time-kill curves. However, these methods expose the bacterial culture to a static or constant concentration of the drugs. During the in vivo treatment of infections, bacteria are exposed to changing concentrations of antibiotics, which are contingent on the individual pharmacokinetics of these drugs. We have designed a two-compartment in vitro pharmacokinetic model that allows the simultaneous study of the activity of two antibiotics with similar or different half-lives against a number of bacteria. Amikacin and azlocillin have been studied alone and in combination in this model against Pseudomonas aeruginosa, a frequent cause of bacteremia in neutropenic patients. In pharmacologically relevant doses, amikacin alone produced rapid bacterial killing, followed by regrowth of resistant subpopulations. Azlocillin alone produced a more gradual reduction of the bacterial inoculum, with ultimate bacteriostasis. Amikacin plus azlocillin produced rapid and complete eradication of the organism. In vitro pharmacokinetic models may prove to be more predictive of clinical outcome than are traditional static in vitro methods used to study antibiotic combinations.

Effect of dose and schedule on cefoperazone pharmacodynamics in an in vitro model of infection in a neutropenic host.

Previous studies have shown that cefoperazone given in frequent, large doses is effective in the treatment of infection in patients with cancer. The pharmacodynamics of 2- and 4-g doses of cefoperazone administered either as a single dose or at 12-hour intervals were studied in an in vitro model that simulates infection in a neutropenic patient. One strain each of Pseudomonas aeruginosa (minimal inhibitory concentration [MIC] = 2 micrograms/ml), Staphylococcus aureus (MIC = 1 microgram/ml), Escherichia coli (MIC = 0.06 micrograms/ml), and Klebsiella pneumoniae (MIC = 0.25 micrograms/ml) was studied. The initial dose reduced the inoculum by approximately 3 logs for the Pseudomonas and the staphylococci and 3 to 5 logs for the other organisms. No significant differences in killing were found between the 2- and 4-g doses. Regrowth of Pseudomonas and staphylococci occurred with the single dose but not with the every-12-hour regimen. These data support the clinical use of cefoperazone in doses every 12 hours.

Pharmacokinetics and pharmacodynamics of intravenous ciprofloxacin. Studies in vivo and in an in vitro dynamic model.

The pharmacokinetics and pharmacodynamics of a 200-mg intravenous dose of ciprofloxacin were studied in normal volunteers and in an in vitro dynamic model that exposes bacteria to changing concentrations of the drug in a neutropenic setting. Peak ciprofloxacin concentrations in vivo averaged 3.2 micrograms/ml. The terminal serum elimination half-life averaged 4.2 hours. The volume of distribution of ciprofloxacin was large and consistent with extensive extravascular distribution. Slightly less than half of the dose was recovered unchanged in urine by 48 hours after infusion. The median serum bactericidal titer against a strain of Escherichia coli was 1:16 or more for at least six hours after infusion, but was only 1:2 against a strain of Pseudomonas aeruginosa immediately after the end of the infusion. Pharmacodynamic studies in the in vitro model with a simulated regimen of 200 mg administered intravenously every 12 hours demonstrated rapid and complete killing of this strain of E. coli following the first 200-mg "dose." For the strain of P. aeruginosa, an initial bactericidal effect was observed due to the eradication of susceptible subpopulations of bacteria; however, regrowth of resistant organisms was observed. These data suggest that a regimen of 200 mg administered intravenously every 12 hours results in rapid killing of susceptible bacteria. Higher doses or combination therapy may be required to prevent the emergence of resistant P. aeruginosa in this model and in the setting of neutropenia.

Clinical overview of enoxacin.

Enoxacin is a new fluoroquinolone that will be available as oral and intravenous preparations. This drug is bactericidal for a wide range of organisms, including Staphylococcus aureus, S. epidermidis, Enterobacteriaceae and Pseudomonas aeruginosa. In addition, Neisseria gonorrhoeae is exquisitely susceptible, as is Branhamella catarrhalis. The evaluation of the clinical activity of enoxacin is still relatively new, but published studies reveal a good deal of potential in the treatment of infections caused by susceptible bacteria in the urinary tract, upper and lower respiratory tracts, bones and joints, and the gastrointestinal tract. The general use of this drug has been associated with few adverse reactions. Further published data, as well as the results of comparative trials now in progress, will permit a thorough clinical evaluation of this useful drug.

Inability of counterimmunoelectrophoresis to detect echovirus in cerebrospinal fluid.

Methods for rapid detection of viral antigens in cerebrospinal fluid (CSF) are needed to aid in the differentiation of viral from bacterial meningitis. The formation of precipitin bands in patients with suspect viral meningitis utilizing viral antisera in a counterimmunoelectrophoresis (CIE) system has been described. To investigate further the possible value of CIE in the diagnosis of viral meningitis, the specificity of the CSF precipitin bands was studied. Precipitin bands were formed between commercially available type-specific antisera and cell culture supernatant fluids. Precipitin bands were also formed when control CSF was used as an antigen. Using type-specific antisera produced against purified virus, enteroviral antigens were not detected in CSF from patients from whom CSF viruses had been isolated. CIE lacks sufficient sensitivity for the detection of echovirus 11 antigens in CSF.

The prevalence of dyspareunia.

A questionnaire regarding sexual experience and dyspareunia was sent to 428 women, of whom 324 (75.7%) responded. Ten refused to participate and one had never had heterosexual intercourse, leaving 313 evaluable responders. One hundred twenty-two (39.0%) had never had dyspareunia and 86 (27.5%) had had dyspareunia at some point in their lives which resolved, either spontaneously or with specific treatment. One hundred five women (33.5%) still had dyspareunia at the time of the survey, 51 of whom had had dyspareunia for their entire active sexual lives. Twenty-two (21%) rarely had dyspareunia, 58 (55.2%) occasionally had discomfort, and 25 (23.8%) had dyspareunia frequently or virtually all the time. Frequency of intercourse was not different among any of the groups analyzed, although 49 (48.0%) of the women reported a decrease in sexual frequency and 35 (33.7%) reported an important adverse effect on their relationships as a result of dyspareunia. Most of the women had not discussed their dyspareunia with a health care professional and were unaware of the cause of their problem.

Comparative anti-staphylococcal effects of gemifloxacin and trovafloxacin in an in vitro dynamic model in terms of AUC/MIC and dose relationships.

To compare the antimicrobial effects of gemifloxacin and trovafloxacin on Staphylococcus aureus, their pharmacodynamics were studied in an in vitro dynamic model. A series of pharmacokinetic profiles of gemifloxacin and trovafloxacin with half-lives of 7.4 and 9.2 h, respectively, were simulated in vitro over an eightfold range of area under the curve (AUC)-to-MIC ratio, from 58 to 466 h. The relationships observed between the intensity of antimicrobial effect (I(E)) and log AUC/MIC were linear, species- and strain-independent and were distinct (not superimposed) for both gemifloxacin and trovafloxacin (r(2) = 0.99 in both cases). At AUC/MICs > 100 h, trovafloxacin had greater effects than gemifloxacin. For example, at an AUC/MIC of 250 h, the antimicrobial effect of trovafloxacin was 17% higher than gemifloxacin. However, due to its higher intrinsic activity, gemifloxacin may be as efficient as trovafloxacin at their clinical doses (320 and 200 mg, respectively): the I(E)s on a hypothetical strain of S. aureus with gemifloxacin's and trovafloxacin's MICs corresponding to the MIC(50)s were similar-290 and 310 (log CFU/mL)x h, respectively. This analysis suggests that both AUC/MIC and dose relationships of the antimicrobial effect are needed for comprehensive comparisons of fluoroquinolone pharmacodynamics.

New pathogens in neutropenic patients with cancer: an update for the new millennium.

As patients with malignant diseases are treated with increasingly potent agents it is likely that they will be subject to infection with an ever broadening array of microorganisms. As a result of the prompt institution of empirical antibiotics at the onset of fever in neutropenic patients, mortality has been reduced but new problems have emerged. First, there has been a shift in the type of infecting organisms responsible for bacteraemia in these patients from predominantly Gram-negative organisms to Gram-positive cocci. Secondly, perhaps as a consequence of the effectiveness of antibiotics, there is increasing concern about infections with antibiotic-resistant organisms. As an example, viridans streptococci are becoming increasingly resistant to penicillin. Thirdly, organisms previously thought to be non pathogens or 'commensals' are now being reported as agents of serious invasive infections in neutropenic patients with cancer. This review will highlight these changes and discuss 'new' pathogens in these patients.

Gemifloxacin and ciprofloxacin pharmacodynamics in an in-vitro dynamic model: prediction of the equivalent AUC/MIC breakpoints and doses.

To compare the antimicrobial effects (AMEs) of gemifloxacin (GEM) and ciprofloxacin (CIP) on Staphylococcus aureus, Escherichia coli and Pseudomonas aeruginosa, a series of pharmacokinetic profiles of GEM (a single dose with the half-life (T(1/2)) of 7.4 h and CIP (two 12 h doses with T(1/2) of 4 h) were simulated in vitro over eight-fold ranges of the AUC/MIC ratio. Species- and strain-independent linear relationships observed between the intensity of AME (I(E)) and log AUC/MIC were not superimposed for GEM and CIP (r(2)=0.99 and 0.98, respectively). The predicted ratio for GEM that might be equivalent to a clinically established breakpoint value of AUC/MIC=125 (mg h/l)/(mg/l) for CIP was estimated at 110 (mg h/l)/(mg/l). It was calculated, that a daily dose of CIP that might provide the same AME as a clinical dose of GEM (320 mg) on a hypothetical strain of S. aureus with MICs=MIC(50)s would be as high as 2 x 3200 mg.

New and unusual infections in neutropenic patients.

Infections in immunocompromised patients with cancer are common and the primary risk factor is neutropenia, usually induced by chemotherapeutic agents. The spectrum of bacterial infection is shifting from gram-negative to gram-positive. The array of fungal infections in cancer patients is expanding to include organisms previously unknown as invasive human pathogens. New species are being defined to explain extant pathologies, and free living algae are now emerging as pathogens in immunocompromised patients. Physicians must remain alert to these emerging pathogens and to the need to evaluate optimal treatments for the usual and unusual infections in neutropenic and other compromised patients with cancer and allied diseases.

In vitro dynamic model for determining the comparative pharmacology of fluoroquinolones.

An in vitro model for determining the comparative pharmacology of fluoroquinolones is presented. The true therapeutic potential of fluoroquinolones against bacterial pathogens may be best understood before clinical testing with the use of in vitro dynamic models. These models simulate pharmacokinetics in humans and can be used to compare different drugs in the same class over a wide range of dosages with respect to the antimicrobial effect (AME). Two models for evaluating AME are described. In one (a two-compartment model), a simple bacterial killing curve is generated after exposure to simulated clinical doses of antimicrobial. In the other (a one-compartment model), AME is defined as the area between the control bacterial growth curve in the absence of drug and the curve that represents bacterial killing and regrowth. This area can be readily measured and is referred to as the intensity of the effect (I(e)). In general, AME is correlated with drug exposure, as simulated in the model at different ratios of the area under the concentration-time curve (AUC) to the minimum inhibitory concentration (MIC) for the organism under study. With this in vitro dynamic model, several fluoroquinolones were tested over a range of AUC/MIC ratios for their AMEs against Staphylococcus aureus, Escherichia coli, and Klebsiella pneumoniae. The data generated illustrate the usefulness of in vitro dynamic models for comparing AMEs of different fluoroquinolones. Because the model incorporates pharmacokinetic variables, it provides a method for comparing various dosage regimens or schedules of administration and is useful in preclinical drug development.

Sexual behavior and contraceptive use. Changes from 1975 to 1995 in college women.

OBJECTIVE: The objective of this study was to compare the sexual practices and contraceptive use in a sample of college women in 1995 with women surveyed in 1975, 1986 and 1989. STUDY DESIGN: We surveyed 336 college women seen at a university student health service or on campus and compared their responses to those of women surveyed at the university in 1975, 1986 and 1989. RESULTS: The proportions of women who were sexually experienced, number of life-time male sexual partners, number of male sexual partners in the past year and frequencies of specific sexual practices were similar over the four survey times. Condom use was reported as the usual method of contraception in 7% of sexually experienced women in 1975, 14% in 1986, 25% in 1989 and 46% in 1995 (P < .00001, linear trend). CONCLUSION: We found little change in sexual practices in this college population over the four survey years, with the exception of an increase in the self-reported use of condoms. Increased educational efforts should emphasize safe sexual practices (barrier methods) to prevent sexually transmitted diseases and highly efficacious methods of contraception (hormonal contraception) to avoid unintended pregnancy.

The antistaphylococcal pharmacodynamics of linezolid alone and in combination with doxycycline in an in vitro dynamic model.

To delineate the possible advantages of linezolid/doxycycline combinations over either drug alone, the in vitro pharmacodynamics of linezolid, doxycycline and linezolid plus doxycycline were studied with Staphylococcus aureus.S. aureus ATCC 43300 and a clinical isolate S. aureus 479 were exposed to twice-daily linezolid and once-daily doxycycline, alone and in combination, for five consecutive days. Three dosing regimens were simulated with each drug alone: linezolid (AUC(24)/MIC 30, 60 and 200 h-L30, L60 and L200, respectively) and doxycycline (AUC(24)/MIC 90, 180 and 520 h - D90, D180 and D520, respectively) and in combination: linezolid plus doxycycline (L30+D90; L60+D180 and L200+D520).With both S. aureus ATCC 43300 and S. aureus 479 exposed to linezolid or doxycycline, the area between the line crossing each time-kill curve at the level of 10(8) CFU/mL and the respective time-kill curve (I(E)) increased with increasing simulated AUC(24)/MIC ratios. Each of the combined treatments produced greater I(E)s than the sum of linezolid and doxycycline I(E)s observed in the respective single drug treatments.This study suggests that linezolid combinations with doxycycline may be synergistic in treating staphylococcal infections.